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1、 i China Council for International Cooperation on Environment and Development(CCICED)Low carbon resilient city development and adaptation to climate changeRiver Basin Governance in the time of Climate Change CCICED Special Policy Study Report CCICED June,2022 ii Special Policy Study Members Co-chair
2、s:Leader of Chinese Team:Li Xiaojiang,Special Advisor,Members of 5th CCICED,Master of National Engineering Survey and Design,Former President of CAUPD Co-leader of International Team:Hans Mommaas,Director-General,PBL Netherlands Environmental Assessment Agency Co-leader of International Team:Fernand
3、o Miralles-Wilhelm,Lead Scientist,Global Water,The Nature Conservancy Special Policy Study Members(Core Team Experts):Wang Kai,President of China Academy of Urban Planning and Design Xue Lan,President of Schwarzman Scholars,Tsinghua University Li Yuanyuan,Vice President of General Institute of Water
4、 Conservancy and Hydropower Planning and Design,MWR,and Member of Population,Resources and Environment Committee of 13th National Committee of CPPCC Pan Jiahua,Member of CASS,former Director of Research Institute for Eco-civilization,CASS Zheng Degao,Vice President of China Academy of Urban Planning
5、 and Design Zhang Jing,Chief Planner of China Academy of Urban Planning and Design Zhang Yongbo,Information Center Director of China Academy of Urban Planning and Design Lv Xiaobei,Chief planner of Western Branch of China Academy of Urban Planning and Design Lv Hongliang,Vice President of Ecological
6、 Municipal Engineering Institute of China Academy of Urban Planning and Design Liu Kunyi,Deputy Chief Planner of Shanghai Branch of China Academy of Urban Planning and Design Yang Bo,The Nature Conservancy Kees BONS,Deltares Jim Best,University of Illinois Renato Paes de Almeida,University of Sao Pa
7、ulo Gerry Galloway,Honorary Professor of Civil and Environmental Engineering,University of Maryland;Chairman of the Institute of Natural Heritage;former Director of Mississippi River Commission Marjolijn Haasnoot,Deltares Han Meyer,Delft University of Technology Xu Xin,The Nature Conservancy Wilfrie
8、d ten Brinke,Blueland Consultancy Au Shion Yee,Asian Development Bank Research Support Team(Consultant and Advisors):Zhang Bing,Director of Territorial Planning,Ministry of Natural Resources Xu Yisong,Director of Shanghai Municipal Planning and Natural Resources Bureau Li Ping,Director of Institute
9、of Quantitative Economics and Technical Economics,CASS Zhang Yongsheng,Director of Institute of Ecological Civilization,CASS iii Bao Qifan,Counselor of Shanghai Municipal Peoples Government,former Deputy Director of Shanghai Port Authority and former Vice President of Shanghai International Port(Gro
10、up)Co.,Ltd.Chen Ming,Deputy Director of Academician Studio of China Academy of Urban Planning and Design Willem Littvoet,PBL Netherlands Environmental Assessment Agency Arjan Harbers,PBL Netherlands Environmental Assessment Agency Henk Ovink,Govt of The Netherlands(Water Envoy)Martien Beek,IenW Howa
11、rd Bamsey,Global Water Partnership LI Lifeng,Food and Agriculture Organization of the United Nations MA Chaode,United Nations Development Programme Onno van den Heuvel,United Nations Development Programme Marcus J.Wishart,World Bank Parameswaran Iyer,World Bank Gary Spiller,Independent consultant Co
12、ordinators:Hu Jingjing Information Center Deputy Director of China Academy of Urban Planning and Design Bob Tansey,The Nature Conservancy Jan Bakkes,PBL Netherlands Environmental Assessment Agency *The co-leaders and members of this SPS serve in their personal capacities.The views and opinions expre
13、ssed in this SPS report are those of the individual experts participating in the SPS Team and do not represent those of their organizations and CCICED.iv Executive Summary 1.Scope and ambition The subject matter of this SPS is no less than a re-alignment of regional economies to the changing river b
14、asins in which they are situated.This cannot happen overnight.But time is short,given climate change,the need for decarbonization and pollution control as well as the opportunities of ongoing economic and demographic shifts.For China,the Yangtze River basin is a key area for the country to address c
15、limate change and achieve ecological civilization.The research team has proposed a governance vision of Yangtze River Basin Life Community for the critical time target of 2050,with the aim of providing a Yangtze River example for international river basin governance.Mutual learning between managers
16、and stakeholders in river basins internationally is key.CCICED should play an active role here,as a rallying point to exchange strategic and practical insights.2.Research Focus Building a framework for integrated watershed assessment,in view of the changing rules of the game.Climate change is alteri
17、ng the hydrological cycle of the basin,exacerbating risks and pressures on the basins water system.Compared to large global river basins,the Yangtze River basin is in a very dynamic stage of development.It faces a higher degree of multiple pressures to achieve decarbonization goals and economic deve
18、lopment,with basin security and resilience and optimal use of shoreline resources already prominent issues facing the Yangtze River basin today.The interplay between using the basin for socio-economic development and ensuring a healthy and sustainable water system needs to be redefined.In the face o
19、f uncertainties brought about by climate change on watershed governance,eight critical steps for sustainable watershed governance and an integrated assessment framework are proposed with the support of an international team,a watershed resilience paradigm is established,and a framework on disaster r
20、isk response is summarized.Examine the long-term trends of climate change and short-term shocks of disaster risks and propose strategies to enhance the resilience of the basin.This study,among other things,reviews the climate change phenomena in the Yangtze River Basin over the past 50 years,and use
21、s empirical research methods to sort out the type,number,and spatial distribution of climate change-induced disasters in the Yangtze River Basin,forming the spatial distribution of major climate disasters in the Yangtze River Basin,as well as disaster risk analysis in key areas.On this basis,we prop
22、ose a strategy for building resilient urban and rural settlements by integrating classical engineering measures and nature-based solutions(NbS)in four aspects:ecological protection,spatial optimization,facility construction,and emergency management,and specifically propose a safety and security stra
23、tegy for the upper,middle and lower reaches of the Yangtze River basin,considering the geographic subdivisions and disaster characteristics of the basin.Resilient strategy.Strengthen empirical studies of river shorelines.Develop localized green,low-carbon and livelihood-oriented shoreline optimizati
24、on strategies.The lower Yangtze River is a highly dense economic and population area in China,and it is also the area with the most prominent water and land conflicts.Using public satellite image data,we invested a lot of effort to draw the shoreline utilization drawings of the Yangtze River from Na
25、njing down to the mouth of the sea in 2010 and 2020,sorted out and analyzed the current development and utilization situation,systematically studied and judged the prominent risks and problems of shoreline utilization in the lower Yangtze River,and proposed a green,low-carbon and livelihood-oriented
26、 shoreline optimization strategy with reference to international v advanced experiences and practices.The SPS also conducted a pre-study on the sustainable development of the delta area at the mouth of the sea with high regional value,high ecological value and high-risk vulnerability.This SPS argues
27、 that special attention should be paid to the safety and social equity of disaster-prone areas such as rural areas,poor areas,remote mountainous areas,and disaster-prone populations such as women,the elderly,and children in watershed governance,and that social and gender equity should be guaranteed
28、as an important goal to enhance the sustainability of watersheds.3.Policy Recommendations The experts involved in this first phase of the SPS on River Basins recommend the following steps to be taken by the Chinese government:Act now on climate change and build a watershed community of life.China sh
29、ould seize the critical opportunities for adaptation to the expected impacts of climate change that are now fleeting.Set new monitoring focused on the impacts of anthropogenic stresses and climate change,carry out risk assessment focused on a long-term basis(2050-2100),and prepare for more than one
30、scenario.Improve security in view of extreme events and restore ecosystems.Pro-active strengthening is needed for protection against a wide range of natural hazards.It can be obtained by applying nature-based solutions and rebalancing natural and man-made elements of the river basin landscape.Build
31、resilient urban and rural settlements to improve Security and Resilience.By making the right choices in the spatial layout of river basins,while combining classical engineering with nature-based solutions,reduce exposure and vulnerability to extreme events,lower disaster risk at the beginning,and in
32、crease resilience of urban and rural settlements including vulnerable groups.Develop comprehensive planning for key industrial port cities in a low-carbon era,selecting major tributaries and deltas for pilot exploration.The economic planning horizon to 2050 will be heavily influenced by the global t
33、ransition to a low-carbon future.Given the longevity of the hardware involved,the uncertainty of regional climate projections and the complexity of changing port city economies,it is urgent to start planning and consulting now.Strengthen integrated water and land management of the basin shoreline.In
34、 particular,promote the transformation of selected parts of the downstream industrial port shoreline into an ecological shoreline and a living shoreline.More generally,river shorelines should be managed as long-term resources.In order to ensure future strategic flexibility,shorelines should be maint
35、ained in their natural state as much as possible.Strengthen response capacities to improve the emergency response capabilities of local governments and the public.Invest in monitoring and early warning systems,and in local response capacities.Pay more attention to gender equality and social equity i
36、ssues in disaster-prone areas and among disaster-affected people.In particular,ensure that efforts to engage stakeholders do indeed empower everyone.4.Suggestions for a Five-Year Program of work The five high-level guiding principles laid out in the scoping study for this SPS lead to a five-year pro
37、gramme of work.These principles will play out differently in each individual river area.We will learn more about these principles,and possibly redefine them,as we learn from the analyses of cases,in China and worldwide.vi Table 1.Proposal for research foci in 5 subsequent years based on the 5 high-l
38、evel guiding principles presented in the scoping study Managing River Areas in Times of Climate Change Principle/Possible research focus#2022-2023 Make good on your responsibility stretching from the headwaters to the coastal seas The mechanism for regional collaboration 2023-2024 Adopt a 100-year p
39、erspective and plan your steps A proactive approach to adapt to projected climate change and increase resilience 2024-2025 Engage everybody who can contribute and develop a shared vision The organization of collaboration in multi-subjects interests 2025-2026 Adapt to climate change and other princip
40、al river stressors in every aspect of the management of river areas Dealing with the uncertainty of climate change and other stressors,and of disasters 2026-2027 Continue to strengthen and innovate Management approaches,knowledge programs,policy tools and forward-looking financing mechanisms,etc.;in
41、ternational exchanges#The order over the years should be fine-tuned in view of opportunities to align with international events The proposed 5-year programme should take advantage of special occasions in each given year,such as the UN Water Decade Conference in early 2023,as they emerge.The work pro
42、gramme each year would see:A stock-taking paper A work conference,with field visits if possible(otherwise,good video reports)A report to the AGM and the wider community reporting on lessons drawn and,importantly,identifying areas for development Along this line,it is proposed to co-organize,or align
43、 with,the following events in 2022/2023:an international seminar considering River basins and Delta areas of the Yangtze,Rhine,and Mississippi,with special focus on the transformational challenges of port city economies October 2022;a side event or similar on water and biodiversity in the context of
44、 maintaining river systems,at or around the Biodiversity COP Kunming;building on the results of the envisaged event at the Biodiversity COP:a side event or similar at or around the UN Water Conference,March 2023.vii Contents 1.SCOPE AND AMBITION.IV 2.RESEARCH FOCUS.IV 3.POLICY RECOMMENDATIONS.V 4.SU
45、GGESTIONS FOR A FIVE-YEAR PROGRAM OF WORK.V FORWARD.1 1.RISKS AND CHALLENGES OF GLOBAL LARGE RIVER BASINS UNDER CLIMATE CHANGE.1 1.1 IMPACT OF NATURAL AND HUMAN ACTIVITIES ON LARGE RIVER BASINS.1 1.2 POSSIBLE IMPACT OF CLIMATE CHANGE ON HYDROLOGY OF LARGE RIVER BASINS.2 1.3 RISKS AND PRESSURES IN LA
46、RGE RIVER BASINS.3 1.4 MULTIPLE CHALLENGES OF RIVER BASIN GOVERNANCE.4 1.5 THE URGENCY OF CHINAS RIVER BASIN ISSUES AND THE IMPORTANCE OF THE YANGTZE RIVER.5 2.NEW PATH FORWARD AND INTERNATIONAL EXPERIENCE REFERENCE IN GOVERNANCE OF RIVER BASIN.8 2.1 EIGHT CRITICAL STEPS AND FRAMEWORK FOR RIVER BASI
47、N MANAGEMENT ASSESSMENT.8 2.2 THE CHANGING GAME:UNDERSTANDING AND BUILDING RESILIENCE IN RIVER BASIN.10 2.3 FRAMEWORK FOR DISASTER RISK ASSESSMENT.11 2.4 NATURE-BASED SOLUTIONS(NbS).12 2.5 LEARN FROM OTHER RIVER BASINS,GLOBALLY.13 2.5.1 The Rhine River:The Room for the River,and recover its natural
48、appearance.13 2.5.2 The Danube River:Climate Change Adaptation Measures Toolbox.14 2.5.3 The Mississippi River:ecological restoration of the lower reaches and the estuarine delta.15 3.GOVERNANCE VISION,GUIDELINES AND ACTIONS OF THE YANGTZE RIVER BASIN FOR 2050.15 3.1 VISION AND GUIDELINES FOR THE GO
49、VERNANCE OF THE YANGTZE RIVER BASIN.16 3.1.1 Vision of river basin governance.16 3.1.2 Eight governance principles.16 3.2 KEY AREAS REQUIRING CONTINUOUS ATTENTION AND ACTIONS.17 4.CLIMATE CHANGE AND DISASTER RISK ANALYSIS OF THE YANGTZE RIVER BASIN.18 4.1 BASIC CHARACTERISTICS OF THE YANGTZE RIVER B
50、ASIN.18 4.2 CLIMATE CHANGE IN THE YANGTZE RIVER BASIN.20 4.3 RISKS CAUSED BY HEAVY PRECIPITATION.22 4.4 IMPACT OF REGIONAL WARMING.23 4.5 RISKS CAUSED BY DROUGHTS.24 4.6 RISKS CAUSED BY EXTREME WEATHERS.25 4.7 SPATIAL CHARACTERISTICS AND RISK ANALYSIS OF MAJOR DISASTERS.26 4.7.1 Spatial characterist
51、ics of major disasters.26 4.7.2 Risk analyses of key areas.26 5.RESILIENCE STRATEGIES OF THE YANGTZE RIVER BASIN IN RESPONSE TO CLIMATE CHANGE.28 5.1 STRATEGIES ON IMPROVING RESILIENCE OF THE YANGTZE RIVER BASIN.28 viii 5.1.1 Strategies on ecological protection.28 5.1.2 Strategies on spatial optimiz
52、ation.29 5.1.3 Strategies on facilities construction.30 5.1.4 Strategies on emergency management.31 5.2 RESILIENCE STRATEGIES OF REGIONS ALONG THE UPPER,MIDDLE,AND LOWER REACHES.31 5.2.1 Strategies on resilience of regions along the upper reaches.32 5.2.2 Strategy on resilience of regions along the
53、middle reaches.33 5.2.3 Strategy on resilience of regions along the lower reaches.33 6.SHORELINES UTILIZATION PROBLEMS AND OPTIMIZATION STRATEGIES IN THE LOWER REACHES OF THE YANGTZE RIVER.34 6.1 ANALYSIS OF THE CURRENT SITUATION OF SHORELINES UTILIZATION.35 6.2 INTERNATIONAL EXPERIENCE IN SHORELINE
54、S UTILIZATION AND MANAGEMENT.38 6.3 GREEN,LOW-CARBON AND LIVELIHOOD-ORIENTED SHORELINES OPTIMIZATION STRATEGIES.39 6.3.1 Promote the industrial function vacating and green transformation of the shorelines along the industrial belt.39 6.3.2 Strengthen protection and restoration of typical aquatic and
55、 terrestrial habitat networks.39 6.3.3 Create a more dynamic waterfront space.40 6.4 CONTINUING CONCERN FOR SUSTAINABLE DEVELOPMENT IN THE DELTA REGION.41 6.4.1 The delta region is a high-value and highly sensitive area that is widely concerned in the world.41 6.4.2 High complexity of the sustainabl
56、e development of the Yangtze Estuary Area.42 6.4.3 Construction of an ecological green beach at the Yangtze River Estuary Area to reserve strategic space for the future.43 7.SOCIAL EQUITY AND GENDER ISSUES IN THE YANGTZE RIVER BASIN.43 7.1 SITUATION ANALYSIS AND PROBLEM IDENTIFICATION.43 7.2 STRATEG
57、IES ON SOCIAL EQUITY AND GENDER IN RIVER BASIN GOVERNANCE.45 8.POLICY RECOMMENDATIONS ON RIVER BASIN GOVERNANCE.47 9.PROGRAMMATIC RECOMMENDATIONS.48 1 Forward Climate change has posed a host of new challenges to basin management.The impact of climate on the water cycle,the resulting flow patterns,sp
58、ecies,ecological processes and other human and natural systems has triggered new situations.Large river basins are vulnerable to various other human and natural stressors(UNEP-DHI and UNEP,2016;Best,2019;Su et al.,2020),which brings a range of challenges and opportunities to river basin management d
59、ue to possible interaction and combination of such stresses.Recognizing the interaction among such stresses and the way to deal with them under climate change has brought unprecedented challenges to future basin management and governance.For China,large river basins,including the Yangtze River,are k
60、ey areas to address climate change for ecological civilization.As with the Rhine River in Europe,the Yangtze River Basin plays a significant role in Chinas regional development paradigm due to its larger area and more complex comprehensive conditions.Preliminary studies of the China Academy of Urban
61、 Planning Design(CAUPD)and the Netherlands Environmental Assessment Agency(PBL)shows that the long-term impact and the short-term shock of climate change on the Yangtze River Basin have emerged,greatly affecting water security and water system in a great many aspects,with rapidly increasing impacts
62、and risks.Experts of CAUPD and the international team in the SPS group fully discussed the issue,reaching a consensus that this work should be committed to promoting the governance action and governance capacity building,including a systematic,synergistic and urgent response to the management of the
63、 Yangtze River Basin under climate change,based on the existing work of the Yangtze River Protection Law of the Peoples Republic of China,the Outline of the Development Plan of the Yangtze River Economic Belt,ecological compensation of the Yangtze River Economic Belt and the SPS on green development
64、 system reform,along with other preliminary studies.Considering the complexity of the issue and the limitations of current studies,this SPS should also combine the long-term arrangement on the seventh session of CCICED with the current action strategy.1.Risks and Challenges of Global Large River Bas
65、ins Under Climate Change 1.1 Impact of natural and human activities on large river basins Globally,large river areas hold huge social,ecological and economic importance.As the birthplace of human civilization,large river basins played a central role in human history,culture,religion and society.They
66、 form regions that provide critical agricultural productivity and support growing populations,provide natural resources for the development of towns and cities,and have fostered the development of some of the worlds most diverse and important ecosystems.As key areas of interrelation between humans a
67、nd nature,river basins are being affected by a host of natural and human factors,which has posed a series of challenges to river basin governance of the present day.The Netherlands PBL study team,in preliminary studies,identified 17 factors affecting river basins,mainly emphasizing two aspects:The f
68、irst is the impact of natural environment on river basins,including flooding,droughts,high waves,landslides,erosion,wildfires and other disasters.These extreme events become natural hazards when people,buildings,or infrastructure are in harms way.The second is the impact from socio-economic developm
69、ent,including both the impact of traditional activities in river basin areas such as dams,water diversions and transfers,sediment mining and fisheries,and the impact from 2 urban settlement and industrial development,such as urbanization and industrialization,port and industrial development,agricult
70、ure,and deforestation in the catchment area.These natural and socio-economic impacts interact,correlate and combine with each other,undermining functions and ecological systems of river basins and posing a host of changes,threats and challenges to river basin management.1.2 Possible impact of climat
71、e change on hydrology of large river basins Hydrological cycles of river basins are seeing changes due to climate change,altering the distribution,timing,and quantity of water in river basins,with implications for human and natural systems.Therefore,the TNC study team made a special study earlier on
72、 the hydrological impact of global large river basins under climate change,reaching the following conclusions:Possible exacerbated seasonality of flow in large river basins by climate change.For instance,river discharge for rivers such as the Ganges,Yangtze,and Yellow River,influenced by monsoonal p
73、recipitation,is projected to increase during the high-flow season1.Possible higher water temperature of rivers by climate change.Global mean river water temperatures are projected to increase on average by 0.8 to 1.6 C for 20712100 relative to 19712000;the largest water temperature increases are pro
74、jected for the United States,Europe,eastern China,and parts of southern Africa and Australia2.Increasing impact of global climate change on extreme weather in large river basins.Global and regional extreme weather and climate events are increasing,both in frequency and intensity3(IPCC,2021).Addressi
75、ng climate change and the frequent occurrence of extreme climate-related weather events and arriving at targeted and practical strategies to improve the level of resilience in river basins is a critical need in todays river basin management.Uncertainty in predicting hydrological changes in specific
76、river basins.There are still significant uncertainties to be resolved in terms of directionality(increases or decreases),magnitudes(relative size of changes)and time scales(seasonality,frequency,short term vs.long term)of climate change impacts,despite the significant progress in understanding the i
77、mpact and significance of climate change on river Figure 1-1 Overview of pressures(challenges)in the river and the catchment area,and in relation to interactions with the outside world 3 basins in the current scientific field.1.3 Risks and pressures in large river basins In the context of climate ch
78、ange,changes in river hydrology will affect the flood control,water resource availability,water quality and biodiversity of large river basins,as well as socio-economic activities including airworthiness conditions,availability for agricultural and food production,energy and mining exploitation,as w
79、ell as power generation,aggravating water risks of current river basins and the pressure faced by water systems.According to PBL preliminary studies,the risks and challenges of climate change to current global river basins mainly focus on the following aspects:Risks of heavy rainfall and flood.In ge
80、neral,climate change will increase the intensity of heavy rainfall events because air can retain more water vapor when it heats up.As a result,flash floods and urban flooding may occur more often unless infiltration and water retention capacities in urbanized areas are increased.The past few decades
81、 saw a sharp rise in losses due to flood in global rivers,with an upward trend of losses caused by floods:from 2010 to 2050,the global population affected by river and coastal floods is expected to increase from 992 million to 1.3 billion4.The frequency of mountain torrents and urban floods will be
82、increased if the infiltration and water retention capacity of urbanized areas remain unimproved.A higher intensity of heavy rainfall events may also increase soil erosion in agricultural areas and nature areas affected by wildfires and may wash down more nutrients to the river5.Drought and water sho
83、rtage.On a global scale,droughts increased in the early half of the twentieth century,decreased in the mid-twentieth century,and increased again starting in the 1980s 6.Model simulations indicate that by the end of this century,the global land area and population in extreme to exceptional drought co
84、uld more than double,each increasing from 3%during Column 1-1:Study on the uncertainty of future scenario prediction for river basin water discharge under climate change TNC conducted a comparative study on the Yangtze River Basin,the Rhine River Basin and the Amazon River Basin,showing an obvious u
85、pward trend between the flow of the Rhine River and the climate change,and no statistically significant trend of the Yangtze River and the Amazon River in different RCP scenarios.The fluctuation range between the minimum and maximum values of the Rhine River is less than 1.2 times,while that of the
86、Amazon River is nearly 5 times,that of the Yangtze River is within 3 times.One credible explanation is that the Yangtze River and the Amazon Rivers are larger in scale,with more influencing factors.Figure 1-2:Discharge flow under four RCP scenarios in the Yangtze River(left),the Rhine River(middle)a
87、nd the Amazon River(right)Results are obtained from the ensemble of CMIP6 models,which have been calibrated to the year 2015,and projected through the year 2100.02004006008000065432019202220
88、2520282034020432046204920522055205820670207320762079208220852088209120942097Yangtze River Basin Discharge(km3/yr)RCP2.6RCP4.5RCP6.0RCP8.50204060800654320028203120342037
89、204020432046204920522055205820670207320762079208220852088209120942097Rhine River Basin Discharge(km3/yr)RCP2.6RCP4.5RCP6.0RCP8.5020004000600080009509876542007200028203402043204620
90、4920522055205820670207320762079208220852088209120942097Amazon River Basin Discharge(km3/yr)RCP2.6RCP4.5RCP6.0RCP8.5 4 19762005 to 7%and 8%,respectively.An assessment of global water scarcity by mid-century,based on scenarios of population growth and climate change,has indicated that most
91、of the projected water scarcity is due to climate change7.Since the world may face water shortage of 40%by 2030,water mismanagement will exacerbate the impact of climate change on water resources and the whole society.Hydropower development.Decarbonization development may prompt further development
92、of hydropower potential as renewable energy.The impacts of climate change itself,such as increased flood frequency or intensity,can also lead to increased pressure to build more dams8.The increasing use of hydropower dams,however,may exert various pressures on river basins,like disturbing water flow
93、 and sediment flow,and damaging aquatic biodiversity.Inland water transport.The functionality of inland waterways can be affected by changes in both high and low flows.High flows can have major impacts such as the suspension of navigation,damage to port facilities due to increased loads on structure
94、s,damage of banks and flood protection works,silting,and changes in river morphology.Changes in low water conditions have a higher impact on inland waterway transport,affecting the loading capacity of(mainly)larger freight ships for longer periods of time9,and on saltwater intrusion in deltas.River
95、pollution.Usually,river pollution can be seen in populous,industrialized and crop-intensive river basins.Climate change,globally,is expected to worsen water quality like that of the drinking water even treated routinely,posing health risks.These risks stem from rising temperature,increased sediment,
96、nutrients and pollutants caused by rainstorms,reduced pollutant dilution capacity during droughts and interruption of treatment facilities during floods10.In addition,increased water temperature reduces oxygen solubility and concentration,and raises the toxicity of pollutants(such as heavy metals an
97、d organophosphates)to fish and other freshwater species11.1.4 Multiple challenges of river basin governance High complexity of river basin issues.The complexity of river areas can be seen in two aspects:the first is the complexity of river basins themselves,which is reflected in the linkages among t
98、he upper,middle and lower reaches of the river system,the interdependence between all activities and land use types within river basins,and the interaction between river basins and the outside world.The combined action of different pressures often has non-linear results,leading to amplified effects1
99、213.The second is the complexity of multiple impacts of climate change on river basins,and different influencing factors may have cross effects,or act on river basins simultaneously to produce additional effects.This destroys functions and ecosystems of river basins and brings a chain of changes and
100、 challenges in managing river basins,which requires us to see river basins as a whole for systematic studies when studying river basin governance.Uncertainty of risks of short-term shock on river basins by climate change.People have made great progress in understanding the impact and significance of
101、 climate change on river basins in the scientific field,believing that the long-term impact of climate change on river basins is relatively certain,such as higher water temperature,increased seasonality of flow and precipitation.However,there is great uncertainty in the short-term prediction of risk
102、 shock to river basins due to limited hydrological directionalities,amplitudes and time scales of specific river basins in existing studies,intensifying the difficulty of river basin governance.It is,therefore,necessary to adopt empirical study to analyze specific river basin problems,so as to provi
103、de successful schemes and strategic cases for decision makers.The safe resilience of urban and rural settlements in river basins is the most urgent.The obvious upward trend of frequency and intensity of global and regional extreme climate events3 also makes river 5 basin management more and more urg
104、ent.There exists a large divide in infrastructure construction and vulnerabilities to disasters in urban and rural settlements,due to great gap in development stages of different river basins.With climate change,frequent extreme climate related weather events and better living standards of people,th
105、e requirements for the safe resilience of river basins are also greatly increased.As for river basin management,it is imperative for us to work towards resilience-oriented river basin governance,combine hydrology,ecology and social sciences into a new and forward-looking scientific method of river b
106、asin resilience,and formulate targeted and practical strategies for better river basin resilience.Integrity,synergy and coherence of river basin governance.River basin governance policies face multiple challenges due to the complexity of river basin issues.In most cases,natural boundaries of river b
107、asins do not match their administrative boundaries,with some river basins even cross-border.Whats more,the management of river basins also involves multiple fields,multiple departments and different administrative levels.Therefore,it is likely to show the disadvantages of segmentation,separate polic
108、ies and repeated construction in governing large river basins.How to cross administrative boundaries at different levels to ensure the consistency,synergy and coherence between cross-border policy objectives and the implementation of cross-sector and cross-level policies is a major challenge.We need
109、 to make overall coordination and systematic institutional mechanism design for many fields,departments and places of large river basins in terms of related policies.The complex interweaving of interest groups in river basin areas.The river basin is complete and complex system,with complicated ecosy
110、stem functions,big regional divides in socio-economic development levels,multiple development forms of different degrees,complex relations,diversified interests and needs,which brings numerous challenges to river basin governance in terms of interest selection and interest balance.We should not only
111、 coordinate all interest relations of upstream and downstream reaches,left and right banks and different regions,industries and departments,but also center on the risks and challenges brought by climate change to regions with different development levels and groups.In formulating related policies of
112、 river basin governance,we should pay attention to all interest relations in the natural,economic,social and cultural systems in river basin areas,comprehensively consider the sustainable development of river basins,make a good choice and balance of interests for fairness,justice and social harmony.
113、1.5 The urgency of Chinas river basin issues and the importance of the Yangtze River More and higher pressures of Chinas river basins compared with other global river basins.In preliminary studies of the Netherlands PBL team,16 major international rivers,including the Rhine,and 20 major rivers in Ch
114、ina were selected for qualitative comparisons for pressures in 17 aspects.According to the studies,it is expected that by 2050,all large river basins will face more pressures,with Chinas large river basins facing more pressures and bigger impact.These pressures bring problems and risks not only in d
115、ams,wetlands and glacier melting in upper reaches of rivers,but also in fisheries,aquaculture,floodplain and wetland loss,as well as in catchment area pollution,deltaic land subsidence,groundwater exploitation,soil erosion and other problems and risks.The next 50 years will be a key time window for
116、Chinas river basin management.Compared with the development of large global river basins in developed regions,Chinas river basins will face more complex challenges in the next 50 years.The study team compared the Rhine River in Europe with the Yangtze River in China,showing that various problems cau
117、sed by industry and pollution had been solved in the Rhine River as early as the 1950s.Today,people pay more attention to frontier issues like biodiversity and 6 energy decarbonization in governing the Rhine River.While the development of Chinas river basin economy is much later,as China didnt see t
118、he beginning of rapid industrialization and urbanization until the 1980s.However,in todays large river basins in China,in addition to solving water pollution prevention and control,water shortage,ecological environment restoration and flood control brought about by urbanization and industrialization
119、,people also put forward issues such as energy decarbonization and biodiversity protection to achieve the strategic goal of peak carbon in 2030 and carbon neutralization in 2060.Therefore,the development of Chinas large river basins will face more complex challenges in the next 50 years.The Yangtze
120、River Basin is the most important support for Chinas development and has the most vitality and potential for the socio-economic development of the country.Covering a total area of 1.8 Figure 1-3 Impacts of pressures on rivers now and in the future:An example of indicative fingerprinting using qualit
121、ative scores(CCICED,2021).Note:In the table,a qualitative low,medium,and high impact label is suggested to characterize the pressures on the rivers in their current situation.In addition,where possible,an i,0,or d is included to indicate whether an improvement(i),deterioration(d)or no change(0)is pr
122、ojected by 2050.7 million square kilometers,the Yangtze River basin,rich in natural resources,accounts for 18.8%of Chinas land area,with the total population and economy exceeding 40%of the country.The Yangtze River Basin,since ancient times,has always faced natural pressures such as floods,droughts
123、 and extreme weathers;After the reform and opening up,it faces a series of challenges brought by the rapid socio-economic development.Today,people have adopted a series of major strategies,such as the Yangtze River Protection Law of the Peoples Republic of China,the Outline of the Development Plan o
124、f the Yangtze River Economic Belt,and the overall policy of eco-priority and green development is taking shape.Understanding complex pressures of the Yangtze River Basin under climate change,the way of addressing climate change and solutions to sustainable development of the basin are not only of gr
125、eat significance to Chinas ecological civilization,but also of key reference value and demonstration to the governance of other river basins in the country.Column 1-2:Comparison of the development stages between the Yangtze River Basin and the Rhine River Basin The countries along the Rhine River Ba
126、sin have entered the post-industrial development stage,the urban population has witnessed lower growth,so pollutant emissions have peaked after the 1980s,and environmental pollution problems have been basically under control;in recent years,the total carbon emissions and per capita carbon emissions
127、of the coastal countries have begun to decline as low-carbon development were accelerated in response to climate change.In the next 15 years,economic scale and urban population of the Yangtze River Basin will also maintain rapid growth,and outstanding pressure still emerges when controlling the tota
128、l amount of pollutants and carbon emissions.At present,the total emissions of major pollutants of the Yangtze River Basin began to decline after 2015;However,the total carbon emissions and per capita carbon emissions are still continuing to increase.Figure 1-4 NOx emission(left)and SO2 emission(righ
129、t)in the Yangtze River Basin and the Rhine River Basin during 1970-2012 8 Figure 1-5 Carbon emission(Left)and per capita GDP(Right)of China and countries along the Rhine River during 1970-2020 2.New Path Forward and International Experience Reference in Governance of River Basin 2.1 Eight Critical S
130、teps and Framework for River Basin Management Assessment The prospect of climate change and the need for ambitious decarbonization of our economies both exacerbate the challenges and open opportunities.We need to redefine the interaction between the use of rivers for socioeconomic development and se
131、curing healthy,sustainable water systems.This calls for a transformation towards sustainable river management that addresses both human interventions and the consequences of climate change.This transformation will not happen overnight.The world is complex,and rivers are not stand-alone silos that ca
132、n be managed in isolation.Agriculture pollutes the river with nutrients,hydropower is an important part of decarbonization that fragments river ecology and disturbs the continuity of water and sediment flow,and the high demand for sand for construction leads to illegal sand mining,to name a few aspe
133、cts of this complexity(Figure 2-1).Figure 2-1 The shift of water steering economy and land use to economy and land use steering water,calling for the redefinition of the interaction between the two.z There is no golden bullet to solve all problems.Bending the trend towards climate resilient and sust
134、ainable rivers requires a machinery of eight steps to shift the outcome of policy and investment strategies in the intended direction(Figure 2-2).9 Figure 2-2 Eight critical steps of the machinery to bend societal trends towards climate resilient and sustainable rivers.This will require amongst othe
135、r things a leap in ambitions,thinking beyond 2030,requiring policy integration and coherence across sectors,new transformative algorithms for decision making,integrated spatial development,and speeding up and scaling up efforts and investments,especially in low-income countries and high-risk regions
136、 in order to prevent structural loss of human habitats.A framework is presented that helps us to investigate river basins and river basin management under climate change by comparing cases and drawing lessons from practices around the globe.Focus is on current and future developments in river basins
137、 due to socioeconomic developments,land use and climate change,on river basin resilience and adaptability,and on river basin management and governance.The investigative framework distinguishes the basin characteristics that define the possibilities in the river basin,stresses that act on the basin,a
138、nd the response of the river system that leads to outcomes in terms of changes in risk and resilience,prosperity and decarbonization,security of the supply of water,food and energy,and progress in achieving the SDGs.The stresses acting on the river basin are climate change,socio-economic development
139、,and internal strategies and policies(Figure 2-3).(Figure 1-3 shows one application of this assessment framework)The investigative framework aims at providing evidence-based recommendations building on experiences from case studies in the Rhine and Yangtze basis and from river basins around the worl
140、d.Each case needs to be analysed following a structured approach to identify as good as possible the drivers,the enabling environment,the hurdles,thresholds,catalysts,deciding measures and actors.10 Figure 2-3 Components of a conceptual Framework for River Basin Management Assessment.2.2 The Changin
141、g Game:Understanding and Building Resilience in River Basin Climate change,its interaction with a wide range of anthropogenic and natural stressors,and the challenge of decarbonization are altering all aspects of river basins,especially the use of land and water resources within the basin,as well as
142、 the corresponding ecosystem services provided by river basins.This is the Changing Game of river basin management we are facing now.The changing game is largely about dealing with uncertainties that pose important challenges in the governance and management of river basins that need to be met.Decis
143、ions need to be made,planning needs to proceed,operations need to continue in areas such as water allocation,storage management,infrastructure,and provision of ecosystem services in general.This calls for understanding and building resilience.Historically,from an ecology perspective,the concept of r
144、esilience focused on bouncing back to previous functions,species,and ecosystem services;resilience in this sense involves resistance to change and recovery from change,or persistence.In addition,two complementary concepts in resilience,particularly applicable to river basins,have emerged:adjusting i
145、n the face of change(adaptation)and transition to new ecological states(transformation).These concepts are illustrated in Figure 6.Persistence,adaptation,and transformation can be thought of as modes that apply to the various dimensions of resilience,e.g.,hydrological,ecological,social,institutional
146、/governance,cultural,engineering/infrastructure,among others.11 Figure 2-4 Conceptual framework to define and characterize river basin resilience.The upper left panel shows the persistence-adaptation-transformation cycle.The right panel shows various resilience dimensions(layers).Each layer is chara
147、cterized by several variables.The lower left panel shows a time series of a hypothetical river basin variable(e.g.,flow,land cover,population,water demand),illustrating the transitions between resilience modes.Managing river basins under a resilience paradigm suggests a more dynamic,interactive form
148、 of engagement,whereby basins may be managed for desired conditions and services(either persistence or adaptation),but potentially with physical and biological characteristics that exhibit limited resemblance to their recent historical state(transformation).The development of holistic management str
149、ategies from headwaters to floodplain to groundwater may be necessary as single system approaches are not sufficient14.This represents a new frontier for hydrologists,ecologists and social scientists and will inevitably require novel and more intensive forms of stakeholder engagement and collaborati
150、ve decision-making to define watershed objectives and management actions.The science of river basin resilience will need to combine insights from these disciplines into a new,forward-looking framework that is only beginning to emerge operationally.2.3 Framework for disaster risk assessment Globally,
151、climate change will affect the number and intensity of extreme events,but the extent to which is uncertain.Pro-active strengthening is needed of protection against a wide range of natural hazards,including floods,droughts,wildfires,and landslides.Future predictions of global risk must also integrate
152、 climate change with socio-economic factors.Disaster risks are rapidly increasing around the world;many regions are experiencing greater damage and higher losses than in the past.Increasing exposure to flooding and increasing damage sensitivity are the main causes of the steeply rising trend in glob
153、al river flood losses over the past decades.The IPCC(2012)15 has high confidence that“increasing exposure of people and River Basin Resilience Dimensionse.g.,hydrological,ecological,social,cultural,institutional/governance,engineering/infrastructure,otherRiver BasinResilienceAbility to change by abs
154、orbing disturbances and reorganize while undergoing changes to retain essentially the same identity and function Ability to become a different kind of river basinwhen the present one is untenableAbility to adjust responses to external drivers and internal changeAdaptationTIMERIVER BASIN VARIABLETran
155、sformationPersistenceAdaptationTransformationPersistence 12 economic assets has been the major cause of long-term increases in economic losses from weather-and climate-related disasters.”.In 2015,the Third World Conference on Disaster Risk Reduction,held in Sendai,Japan,approved 2015-2030 Sendai Fra
156、mework for Disaster Risk Reduction and confirmed four priorities for action including global disaster prevention and reduction,and called on countries around the world to increase investment in disaster reduction,strengthen resilience construction,and reduce losses caused by natural disasters.The fo
157、ur priorities for action are:understanding disaster hazards,strengthening disaster reduction management,increasing investment in disaster reduction,and disaster prevention and recovery and reconstruction.The Sendai Framework for Disaster Risk Reduction also put forward 6 key dimensions and 10 specif
158、ic elements to enhance resilience against disasters Error!Bookmark not defined.(Figure2-5).It should also be recognized that restoring ecosystems can enhance protection against disasters and risks to some extent,and thus rebalancing natural and man-made elements of the river basin landscape.Focus sh
159、ould be on co-management of water and land,for instance by using the opportunities of more wind and solar on land to reduce the adverse effects of hydropower on river systems.A shift to regenerative agriculture can bolster lands resilience,while renewables should be sited on lands less suitable for
160、other uses.2.4 Nature-Based Solutions(NbS)In theory,NbS can address multiple dimensions and modes of river basin resilience while providing co-benefits to communities,businesses,and nature1718.Although some functions of NbS can be fulfilled by built infrastructure,the high flexibility and adaptive c
161、apacity of NbS,highly relevant in the context of uncertain future change,are specific advantages.Uncertainties created by climate change and an unpredictable future render static solutions with high sunk costs and low adaptive capacity,such as large reservoirs and similar gray infrastructure,increas
162、ingly risky investments.NbS are often smaller,more affordable,more flexible,and more multipurpose than conventional interventions1920.For example,single NbS interventions can mitigate effects of floods and droughts both,which is rarely found in engineered interventions,or can address water quality t
163、hrough interventions that also improve habitat,capture additional carbon dioxide,and can improve health and Figure 2-5 Priorities for action key dimensions and specific elements of resilience of Sendai Framework for Disaster Risk Reduction(sorted according to the data of UNDRR16)13 well-being of com
164、munities.As such,NbS are more compatible with the type of adaptive solutions and no-regret strategies that are advocated in the context of uncertain future change.Column 2-1:Nature-Based Solutions(NbS)An umbrella-type approach concept to achieve the UN Sustainable Development Goals(SDGs)by actively
165、using ecosystem services,encompassing many ecosystem-based solutions for various sustainable development issues,such as solutions for ecosystem-based adaptation,ecosystem-based disaster risk reduction,natural infrastructure,green infrastructure,and nature-based climate change.The IUCN defines NbS as
166、 actions that effectively and adaptively address societal challenges and bring benefits to human well-being and biodiversity through the protection,sustainable management,and restoration of natural or man-made ecosystems21.Eggermont et al.(2015)22used two gradients to classify NbS types involving th
167、e extent of NbS intervention on ecosystem/biodiversity diversity,and the magnitude of ecosystem service enhancement resulting from the implementation of NbS.Figure2-6 Different types of NbS(Eggermont et al.,201522)2.5 Learn from other river basins,globally The river Rhine in Europe is an example of
168、a river that already in the 1980s made a turnaround to tackle pollution when a chemical disaster caused extensive ecological damage stretching from Switzerland to the North Sea.The turnaround proved successful.It was exemplified by the symbolic return of salmon in the river.The transformation is sti
169、ll ongoing and includes other river characteristics as well.Examples are the increase of discharge capacity by the Room for the River Program in the Netherlands and measures to restore ecological qualities of the floodplains.In the coming years,measures to reduce the adverse impacts of droughts unde
170、r climate change will be a focal point for river managers in the area.And all these elements of the transformation of the Rhine have been and will be designed with the continuation of river functions for society in mind.The example of the Rhine and many examples of rivers throughout the world illust
171、rate that we do not have to reinvent the wheel.We can learn how to take the eight critical steps of the transformation towards a sustainable future by learning from other rivers,globally.2.5.1 The Rhine River:The Room for the River,and recover its natural appearance Since the mid-20th century,the Rh
172、ine River has faced increasing problems of river pollution and 14 flooding,and the focus of governance has gradually expanded from pollution control to flood control and biodiversity restoration.A major disaster(fire in Basel,Switzerland)in 1986 caused unprecedented,large-scale pollution of the Rhin
173、e.This has led to a governance shift of more strict and transboundary pollution control and ecological restoration of the river.Peak river discharges occurred in 1993 and 1995.The one in 1995 almost caused dike failure(and flooding)of one of the branches of the Dutch Rhine River system.This initiate
174、d the program(with 39 measures)to give more Room for the River.This program was a governance shift:before the 90s river flood protection policy was all about high and strong dikes;since the near-floodings of the 90s policy is about combining strong and high dikes with increasing the discharge capaci
175、ty of the river(and hence more room for the river).Column 2-2:The Netherlands“Room for the River”:Nijmegen Practice Project The floods of 1993 and 1995 in the Netherlands cast doubts on the old approach to flood prevention strategies:that land reclamation and building dikes were positive approaches
176、to water management.Thus,Room for the River as a newer approach was considered-rather than restricting water,the area around the river could accommodate fluctuating tides.This is done through a series of over 30 measures,in which the area will have been“.lowered and broadened the floodplain and crea
177、ted river diversions and temporary water storage areas.”Marshy riverine landscapes have also been restored to protect biodiversity and aesthetic value.One of the Room for the River measures exemplifying environmental adaptation is the Room for the Waal project in Nijmegen.This measure moved the dike
178、 at Lent(on the north side of the city of Nijmegen),inwards and dredged an ancillary channel in the floodplain in order to help drain the river during high water.The project of moving of the dike had a double goal of protecting the city from floods and improving the urban spatial quality.Building th
179、e channel created an island along the Waal,which forms a city park for Nijmegen with urban development possibilities(https:/www.ruimtevoorderivier.nl/room-for-the-waal/).Figure 4-8 Comparison of Nijmegen pictures before and after the construction of Nijmegen“Returning Land to River”project 2.5.2 The
180、 Danube River:Climate Change Adaptation Measures Toolbox From the 19th century to the mid-20th century,the core issues of early governance of the Danube River basin were navigation and hydro-energy development.After the 1980s,it centered on water pollution prevention and ecological protection proble
181、ms.In 1994,the 11 countries along the Danube established the International Commission for the Protection of the Danube River(ICPDR)to coordinate water pollution prevention and control,flood control and disaster reduction,and other governance work.After 2010,the International Commission for the Prote
182、ction of the Danube River began to attach importance to the impact of climate change on the Danube River Basin,and formulated two editions of the Strategy on Adaptation to Climate Change in 2012 and 2018 respectively.For the impacts and challenges 15 of climate change on the Danube River,a series of
183、 Climate Change Adaptation Measures Toolbox are proposed from the aspects such as climate change and basin vulnerability analysis,water resources and water environment management,flood risk management and response,and drought management23.Column 2-3:Climate Change Adaptation Measures Toolbox ICPDR f
184、ormulated a set of Climate Change Adaptation Measures Toolbox for the Danube River basin,which provides comprehensive and easy-to-use governance measures from governance fields,types of measures,time scales,and other different dimensions.The governance fields involve agriculture,ecosystem,biodiversi
185、ty,navigation,hydropower,flood,and so on;The types of measures include basic preparation measures,ecosystem-based measures,technical measures,action and management measures,and policy measures;The time scales include long-,medium-,and short-term.The toolbox can be inquired on the website:http:/www.i
186、cpdr.org/main/climate-changeadaptation.2.5.3 The Mississippi River:ecological restoration of the lower reaches and the estuarine delta From the 19th century to the mid-20th century,the governance focus of the Mississippi River was navigation and flood control,and a series of relevant projects were i
187、mplemented along the river,causing some damage to the ecological environment of the Mississippi River.By the 1980s,67%of the wetlands along the main stem had disappeared.Since the 1950s,increasing attention has been paid to restoration of the ecological system.Since the 1980s,basin ecology restorati
188、on plans such as the“Plan for Restoring the Upper Mississippi River”and“Plan for Restoring Americas Greatest Rivers”have been implemented in the Mississippi River24.In particular,after 2006,comprehensive ecological restoration work was carried out in the lower reaches and the delta coastline,which s
189、pecifically included restoration of wetlands and woodlands on both sides of the shoreline and on the river island,as well as shoreline restoration and protection measures for the estuarine delta25.Column 2-4:Ecological restoration measures for the lower reaches of the Mississippi River(“Plan for Res
190、toring Americas Greatest Rivers”)After 2006,comprehensive ecological restoration work was carried out in the lower reaches of the Mississippi River and the delta coastline,coordinating with 6 state governments along the shoreline for more than 200 implementation projects.Among which 3 aspects were a
191、dvanced in response to climate change.Firstly,the dikes were trenched to restore tributary flow and aquatic habitat;currently 30%of the downstream dikes have been trenched.Secondly,frequently flooded land in the floodplain were restored to wetlands and woodlands,with approximate 110 km2(27,000 acres
192、)of land already subscribed for restoration to ecological space26.Thirdly,measures such as sediment transfer and shoreline restoration were implemented in the estuarine delta to mitigate shoreline erosion and flood caused by storms and rising sea level.Two diversion projects are planned in Louisiana
193、 at the estuary of the river,so as to make more river sediments retransfer from cities into the estuarine delta.3.Governance Vision,Guidelines and Actions of the Yangtze River Basin for 2050 2050 is a key time node,which is not only the most critical decade from Chinas grand development 16 goal of t
194、he Second century towards Carbon neutrality in 2060,but also the key node for the 2050 strategic long-term vision of EU and the 2050 net zero emission long-term strategy of the U.S.For the grand goal,we should not only formulate a shared vision and goals in various fields and regions,but also focus
195、on the present to form guidelines and key areas for current actions.3.1 Vision and guidelines for the governance of the Yangtze River Basin 3.1.1 Vision of river basin governance We should deeply analyze the changing characteristics of water resources in the Yangtze River under climate change and th
196、e coordination between socio-economic development and biodiversity protection in river basins,adhere to Step up conservation of the Yangtze River and stop its over development,build the Yangtze River Basin into a greener,low carbon,more coordinated and balanced,safer and more resilient,more inclusiv
197、e,more open and co-governed river basin life community to provide a Yangtze River example for the governance of global river basins.3.1.2 Eight governance principles Principle 1:Shared vision and co-governed river basins.We must pay attention to synergies among central and local governments,departme
198、nts and industries,regions,governments and market society,and to the synergies among the trunk stream and tributaries,upstream and downstream areas,urban and rural intensive areas and marginal areas,villages and cities.Additionally,we must form a long-term vision based on common understandings of is
199、sues and values,as the basis for multi-party policies and concerted actions,and formulate policies and action programs crossing department authorities,administrative levels and regional boundaries;Also,we must give full play to the power of the market and society and combine top-down policies with b
200、ottom-up actions for real sustainable river basin governance.Principle 2:Shared responsibilities from sources to coastal areas.Taking river basins as a whole,we should not transfer problems from upstream to downstream areas,nor transfer them through time.We must adopt a river basin-based comprehensi
201、ve approach,recognize key roles of water in river basin development for human-nature coordination,combine climate change with socio-economic development,fulfill overall responsibilities from sources to estuaries of different regions,departments and groups.Furthermore,we must make use of overall func
202、tions of river basins to establish an integrated and coordinated governance system for the adaptation and mitigation of climate change.Principle 3:Blueprint based on 100 years.In terms of river basin governance,we must have long-term goals and value orientation,pay attention to longer-term interests
203、,comprehensively consider major issues related to the survival and development of human civilization such as carbon neutrality and biodiversity,and incorporate river basin governance into key actions of the United Nations Convention on Biological Diversity and the Convention on Climate Change.Princi
204、ple 4:Focus on and respond to uncertainty.For river basin development,we should confront the long-term pressure brought by climate change,and deal with the short-term impact and uncertainty of disaster risks.Also,we should systematically understand long-term roles of river basins on economy,populati
205、on,nature,water areas and oceans,and form multi-scenario prediction through long-term monitoring,comprehensive modeling and real-time data analysis to deal with the complexity of river basin problems and the uncertainty of climate change.Principle 5:Controlling the relation between river basins and
206、settlements.We should not only respect and control macro integrity of river basins,but also respect and understand their divides between 17 medium and micro zoning,especially in urban and rural settlements with highly dense population and economy.We must pay attention to the vulnerability of such hi
207、ghly exposed areas and formulate zoning and classified governance strategies based on urban and rural settlements from aspects of ecological protection,space optimization,facility construction,collaborative response and so on.Principle 6:Controlling the relation between regional development and soci
208、al equity.In terms of river basin development,we should improve resident well-being in the whole river basins and pay close attention to imbalance of river basin development,not only focusing on marginal and disaster-prone areas such as villages,small towns,flood storage and detention areas and ecol
209、ogical protection areas,but also on vulnerable groups such as women,the elderly population and left-behind children.We should also pay attention to vulnerabilities of such areas and groups,and strengthen the construction of regional equity,social equity and gender equity mechanisms and the security
210、of vulnerable groups in disaster-prone areas.Principle 7:Controlling the relation between artificial measures and nature-based solutions.As for river basin governance in response to climate change,we should be people-oriented,respect nature and fully understand system operation modes and ecological
211、service functions of river basins,not only centering on underlying roles of systematic defense projects in improving river basin safety,but also on the advantages of nature-based solutions in alleviating pressures of water security,maintaining the integrity,flexibility and adaptability of the ecosys
212、tem for better overall integration to effectively enhance the resilience of river basins to resist disaster risks.Principle 8:Innovative exploration and strengthened actions.We should continue to strengthen innovative exploration in management methods,knowledge plans,policy tools,forward-looking fin
213、ancing mechanisms,the relevant knowledge of sustainable development under climate change,global exchange and share,in order to further transform the knowledge into joint global actions.3.2 Key areas requiring continuous attention and actions Improving the resilience of urban and rural settlements in
214、 river basins.With climate change and socio-economic development,dealing with disaster risks and reducing vulnerabilities are the most urgent in the Yangtze River Basin.Therefore,we must firmly abide by the bottom line of water security,attach great importance to urban and rural settlements along ri
215、ver basins,and adopt classified and zoning response strategies to improve the adaptability to climate change.Comprehensive governance of river basins and coastlines.Catchment areas are main stressors of river basins,which will have a large-scale and long-term impact on other systems,highlighted by t
216、he pressure brought by the utilization of shoreline spaces to river basins.Therefore,strengthened comprehensive assessment of shorelines and optimized shorelines governance are critical to deal with pollution in densely populated urban and rural areas of river basins,which should be paid special att
217、ention.More attention to deltas and other key areas.Contradictions between the protection and development of large river basins are prominent in deltas,one of the most sensitive areas to the impact of climate change in the future.Therefore,in addition to urban and rural settlements and river shoreli
218、nes,we should also pay close attention to key areas such as estuary deltas,flood storage and detention areas and important agricultural natural ecological zones,speed up the identification of all risks in key areas and strengthen the risk response under climate change.More attention to disaster-pron
219、e areas,groups and fields.We should fully consider the differences of the impact of climate change on spaces and factors of river basins,monitor and identify disaster-prone areas,groups and fields in river basins that are seriously affected by climate change.Targeted and diversified measures shall b
220、e taken for disaster-prone areas and fields and vulnerable groups 18 to ensure that different regions and groups have equal disaster prevention capacities and the right to equitable development when facing disaster risks brought by climate change.Optimized ideas and methods of river basin planning a
221、nd design.In river basin-related planning,facilities and architectural design,we should fully consider the impact of climate change,put forward comprehensive solution systems integrating engineering measures and non-engineering measures,so as to foster the sustainable development capacities of river
222、 basins.Also,we should,with holistic and systematic thinking,coordinate river basin development planning,land space planning,ecological protection,resource utilization,disaster prevention and other special plans,and make multiple subjects be part of the planning preparation for better joint implemen
223、tation mechanisms.A mechanism for long-term monitoring of pressures of the Yangtze River Basin by climate change.We should strengthen monitoring,establish a monitoring and evaluation information network throughout the whole river basins,and timely understand the long-term trend and short-term risks
224、of climate change in river basins.Additionally,we should realize early warning through combined modeling scenarios and data analysis,scientifically and pragmatically formulate adaptation paths and measures,and make timely adjustments based on uncertain factors.Advocating and promoting nature-based s
225、olutions.We should take NbS as important tools to alleviate water pressure and protect ecological security in river basins,combine NbS with traditional system engineering solutions,and maintain integral ecosystem while reducing floods and other disaster risks.Using NbS,we should also improve the fle
226、xibility and adaptability of river basin governance,and dynamically adapt to the uncertain impact of climate change on river basin governance in view of complex geographical conditions and socio-economic spatial differences of the Yangtze River Basin.4.Climate Change and Disaster Risk Analysis of th
227、e Yangtze River Basin Disaster risk is currently the primary and urgent issue in the Yangtze River basin in the face of climate change,which is mainly affected by four major climate change factors:heavy precipitation,warming,drought and extreme weather.By retracing the frequency,impact scale,loss an
228、d spatial distribution of disasters in history,we combine the distribution of population,towns and economic industries in the basin in order to study the exposure of disaster impacts and further study the spatial characteristics of disaster risks in the Yangtze River basin under the influence of cli
229、mate change.4.1 Basic characteristics of the Yangtze River Basin The Yangtze River is the largest river in China and the third largest river in the world,with a total length of 6,300 kilometers and an area of about 1.8 million square kilometers;From west to east,it flows through 11 provinces,autonom
230、ous regions and cities,then into the East China Sea.Geographical characteristics.The Yangtze River Basin crosses Chinas three-level topographic ladder,with great differences in the physical and geographical characteristics of the upper,middle and lower reaches.The terrain of the Basin is high in the
231、 west and low in the east,with the total drop from the river source to the estuary of about 5,400 meters.Its upper reach is dominated by plateaus,mountains and canyon terrains,with a big riverbed gradient and rapid flow.Its middle reach is with alternatively distributed plains,hills and mountains;ri
232、vers herein are tortuous and wide,with various tributaries.Its lower reach is dominated by plains,with deep and wide water and short tributaries.Climatic characteristics.Most parts of the Yangtze River Basin are in the subtropical monsoon region,with big regional climate differences due to its terra
233、in.Cold winter and hot summer,obvious dry and wet seasons represent basic characteristics of the climate,with an average annual precipitation of 19 1,067 mm for years.It sees uneven temporal and spatial distributions of annual precipitations and rainstorms,which is greatly subject to extreme climate
234、 events.Hydrological characteristics.The Yangtze River Basin is rich in water resources,but with uneven distributions in its upper,middle and lower reaches.Its average water resources for years are 995.9 billion cubic meters,accounting for about 36%of Chinas total water resources,and its water resou
235、rces per unit land area is 59,5000 m3/km2,about twice Chinas average.Its middle reach sees the most surface water resources,while its upper and lower reaches see less.Figure 4-1 River system of the Yangtze River Basin Demographic characteristics.The Yangtze River Basin is the main gathering area of
236、Chinas population and economic activities.The land area is only 21.3%of the country,with 42.9%of Chinas population though.The year 2020 witnessed the total population of the region of about 606 million,with a population density of about 296 people/km2,twice the national average Economic characterist
237、ics.There is a significant gradient divide in development levels of economy and urbanization along the upper,middle and lower reaches of the Yangtze River Basin.The Yangtze River Delta,in the lower reach,is densely populated and economically developed,with a population density of about 800 people/km
238、2 and per capita GDP close to 20,000 US dollars.The urbanization rate is generally higher than 70%,close to the development level of the Rhine River Basin in the 1990s.The population density in its middle reach is about 330 people/km2,the per capita GDP is about 10,000 US dollars,and the average urb
239、anization rate is about 60%,close to levels of high-income countries in the World Bank.In its upper reach,the population density is low,about 180 people/km2,the per capita GDP is less than 10,000 US dollars,the urbanization rate is between 50%-55%,still in a relatively underdeveloped stage.Urbanizat
240、ion characteristics.Cities and towns in the Yangtze River Basin are densely distributed,with the urbanization rate of 63.2%in 2020,ushering in middle and later stages of urbanization.There are 243 autonomous regions and cities,coupled with 584 county-level cities,most of which are distributed along
241、the Yangtze River.Twenty-eight large cities of more than one million,along with numerous small and medium-sized cities and towns are perched on both sides of its trunk stream and main tributaries.Urban agglomerations in the Yangtze River Delta,Chengdu,Chongqing and the middle reach of the Yangtze Ri
242、ver have been formed.20 Figure 4-2 Distribution diagram of per capita GDP(left)and population density(right)of regions and counties in the Yangtze River Economic Belt in 2020 4.2 Climate change in the Yangtze River Basin Pressures of climate change on the Yangtze River Basin are mainly heavy precipi
243、tations,droughts,rising temperatures and extreme weathers.Heavy precipitation.Climate warming leads to more heavy precipitations.According to studies,there was an inconspicuous time change of the total rainfall in China,but the intensity of rainfall was increasing.Extreme precipitations(extremely li
244、ttle rain and extremely rainy)throughout the Yangtze River Basin and its tributaries were regular in terms of time change.On the whole,there was an increase in the change rate of heavy precipitations in the Yangtze River Basin since 196027.Among 60 cities with serious waterlogging identified by the
245、State Council in 2017,36 are in the Yangtze River Basin.There were 166,000 geological disasters and hidden dangers in 11 provinces(cities)of along the Yangtze River Economic Belt in 2018,about 58%nationwide.Figure 4-3 Change rates of extreme rainfalls in the Yangtze River Basin from 1960 to 2015 Ris
246、ing temperature.Affected by global warming,the average temperature of Yangtze River Basin significantly increased from 1970 to 2014(the temperature tendency rate was about 0.4/10A),and average temperatures in four seasons,in the coldest months and the hottest months soared28.From 1970 to 2015,the gl
247、acier area in the Yangtze River Basin has shrunk by 14.5%,the thickness of frozen soil in the source region of the Yangtze River,Yellow River and Lancang River has cut down by 5.6 cm per decade since 1984.In 201829,the number of summer hot days(temperature35)of more than 30 in the whole Basin involv
248、ed about 220 million people in 40 cities.The rising rate of Chinas 21 coastline is slightly higher than that of the global average,and it is predicted to rise by 0.145-0.2m by 2050.Figure 4-4 Spatial distribution of annual average temperature changes in the Yangtze River Basin from 1970 to 2014 Drou
249、ghts.Climate change may lead to droughts in some areas of the Yangtze River Basin.Based on relevant studies,under the scenario of global warming of 1.5,the annual precipitation in the middle and lower reaches of the Yangtze River drops by 5%compared with that in 1986-2005;Under the scenario of globa
250、l warming of 2.0,it drops by 3%30.The drought risk is mainly in the upper reaches.The year 2018 saw 862 forest fire points in the whole Basin.The number of fire points went down from 2010 to 201831.Figure 4-5 Prediction of annual precipitation changes in the middle and lower reaches of the Yangtze R
251、iver under climate warming Extreme weather.Relevant studies predict that under the goal of global warming of 1.5,extreme precipitations in the Yangtze River Basin once in 20 years and once in 50 years will rise by 10%and 9%from 1986 to 2005;Under the goal of global warming of 2.0,they will increase
252、by 14%and 15%.Spatially,they increase generally in the middle and lower reaches,while drop in the upper reaches.Typhoons can be seen usually in the lower reaches of the Yangtze River.From 1949 to 2010,the average number of times affected by typhoons in cities in the Yangtze River Delta was 65.432 wi
253、th an increasing trend in recent years.Jiangsu,Anhui,Hubei,Hunan and Yunnan saw serious low-temperature freezing disasters in China33,and in recent years,the low-temperature freezing disasters and wind hail have shown a decreasing trend.In terms of overall losses caused by extreme weathers,casualtie
254、s and house damage have decreased,but direct economic losses like infrastructure damage have continued growing.22 Figure 3-6 Impact frequency of typhoon disasters in the Yangtze River Basin from 1980 to 2016 Figure 3-7 Spatial distribution of affected areas of low-temperature freezing disasters and
255、snow disasters in the Yangtze River Basin from 2004 to 2020 Based on data of CMA Tropical cyclone data center Sources:China Statistical Yearbook,China Statistical Yearbook on Environment 4.3 Risks caused by heavy precipitation Increased flood risks in the trunk stream and main tributaries of the mid
256、dle and lower reaches of the Yangtze River.Since 1840,catastrophic floods and severe floods in the Yangtze River Basin mainly occurred along the trunk stream of the middle and lower reaches.River basin flood occurred in the Yangtze River in 1998,five provinces in the middle and lower reaches were se
257、riously affected.334 counties(cities and districts)were affected,2.2185 million houses collapsed and 1,526 people died34.In 2020,there occurred river basin floods in the Yangtze River,with five numbered floods in the trunk stream and the maximum inflow of the Three Gorges Reservoir since its establi
258、shment.A total of 378 rivers in the whole Basin saw floods exceeding the alarm water level,156 rivers saw floods exceeding the guaranteed water level,and 51 rivers saw floods exceeding historical highs35.From 2010 to 2020,the population of in the middle and lower reaches of the Yangtze River continu
259、ed to move to large cities along the trunk stream of the Yangtze River and the main tributaries,causing higher flood risks in big cities.Figure 4-8 Chinas major flood points Figure 4-9 Distribution of flood risk levels in the Yangtze River Basin Source:Shi Peijun,Atlas of Natural Disaster System of
260、China,Science Press,2003 Higher risks of waterlogging in large and medium-sized cities along the trunk stream and main tributaries.A total of 36 cities with serious waterlogging along the Yangtze River Basin determined by the State Council are mainly in Hubei(10),Hunan(9),Anhui(6)in the middle and l
261、ower reaches and Sichuan Basin(5)in the upper reach,most of which are cities along the trunk stream of the Yangtze River and main tributaries such as the Jialing River,the Han River,the Xiangjiang River and the Ganjiang River.23 The total population of 36 cities is 93.37 million,an increase of 18.97
262、 million from 2010 to 2020.Affected by heavy rainfalls,risks of waterlogging in major cities like Chengdu,Chongqing,Changsha,Hefei,Wuhan and Nanchang may further increase in the future.Figure 4-10 Changes of permanent resident population in 36 severely waterlogged cities in the Yangtze River Basin f
263、rom 2010 to 2020 High risks of geological disasters in mountainous areas of Sichuan,Chongqing,Yunnan and Guizhou along the upper reach of the Yangtze River.Geological disasters in the Yangtze River Basin are mainly in mountain areas in west Sichuan,some areas in south Sichuan,northeast and southeast
264、 Chongqing,west and south Guizhou,the Xiaojiang River,the Lancang River and the Jinsha River in Yunnan.The overall population density in the above areas is not high,the population of some counties(autonomous regions,cities)in west Sichuan,northeast Chongqing,Southeast Chongqing,west Guizhou,south Gu
265、izhou,and west Yunnan has increased in recent years.Among them,the population of Dali City in west Yunnan and Dafang County in west Guizhou increased by more than 80,000,with further increasing risk of residential safety.Figure 4-11 Change of permanent resident population in areas with frequent geol
266、ogical disasters in the Yangtze River Basin from 2010 to 2020 4.4 Impact of regional warming Glacier retreat and frozen soil melting at the source of the Yangtze River threatening the ecosystem.Glacier retreat and snow line rise are mainly concentrated in Tanggula Mountain and 24 Bayankala Mountain,
267、threatening the upstream ecological areas such as the source of the Yangtze River,the Yellow River and the Lancang River,which may lead to the less biodiversity and changed community structures and functions.Glacier retreat also affects the hydrological cycle of the Yangtze River Basin and trigger f
268、loods in the lower reach.About 40 glacial lake floods have occurred in the Qinghai Tibet Plateau since 1935,with the average glacier melt runoff in the Tuotuo River Basin at the source of the Yangtze River increased by 120.89%from 1960 to 200036.The depth of frozen soil in Qumalai,Zaduo,Chengduo,Maq
269、in 37.Frozen soil degradation greatly changes soil temperature and humidity,reduces the content of organic matter in the soil surface,leading to risks of vegetation degradation,reduced vegetation coverage and shortened plant heights,especially in alpine meadows and alpine swamp meadows.More threat o
270、f heat waves in Chongqing along the upper reach,most places along the middle reach,metropolitan area in the south along the lower reach.In 2018,the number of summer hot days(temperature35)of more than 30 in the whole Basin involved the surrounding areas of Chongqing,most areas of Hubei,Hunan and Jia
271、ngxi in the middle reach,Anhui and south Zhejiang in the lower reach.If the global temperature rises from 1.5 to 2,the intensities of extreme heat waves in the Yangtze River Delta,the middle reach of the Yangtze River,Chengdu and Chongqing may be increased by 4.1 times38.The metropolitan areas in th
272、e Yangtze River Basin are densely populated and growing fast.From 2010 to 2020,the metropolitan areas in 11 provinces along the Yangtze River Economic Belt increased by 30 million,91%of the total increment.In the future,Chongqing,Wuhan,Changsha,Nanchang and other metropolitan areas will face more se
273、vere high temperature and heat wave risk.Coastal and lakeside areas along the lower reach threatened by sea-level rise.Coastal areas like Shanghai,Nantong and Zhoushan have low terrains and high risks of sea-level rise.Areas around the Hongze Lake,the Chaohu Lake and the Poyang Lake in the middle an
274、d lower reaches are low-lying,which may be easily submerged.Shanghai,Zhejiang province,Jiangsu province and Anhui province along the lower reach have dense and fast-growing population.The population in areas with high and higher risks of sea-level rise was 15.46 million in 2020,with a total increase
275、 of 550,000 from 2010 to 2020;The population in the medium risk area was 63.98 million in 2020,with a total increase of 8.64 million from 2010 to 2020.As the population further gathers,the threat posed by sea-level rise will further intensify.4.5 Risks caused by droughts Risks of water shortage in s
276、ome areas in the middle and upper reaches.From 1981 to 2010,regions with annual drought days exceeding 50 mainly include Sichuan Basin,Panxi of Sichuan,the junction of Yunnan,Guizhou and Sichuan,southeast and south Yunnan,among others;Regions with annual drought days exceeding 40 include most parts
277、of Yunnan,southeast Guizhou,north Hubei,north Hunan,south Jiangxi,among others39.Among these areas,water consumption in some places like Sichuan Basin,southeast Yunnan and south Jiangxi has seen continuous increase in recent years,and the ability to address droughts needs to be further improved.25 F
278、igure 4-12 Spatial distribution of population with inaccessibility of drinking water due to droughts in the Yangtze River Basin from 2006 to 2020(Source:Bulletin of flood and drought disasters in China)Figure 4-13 Number of forest fires in the Yangtze River Basin from 2003 to 2020(Source:China Stati
279、stical Yearbook)High risks of forest fire in southern mountainous area of the upper and middle reaches.There exist a great many forest fire points in south Sichuan,south Yunnan,west Guizhou,south Hunan,south Jiangxi and north Hubei,where the overall population density is low,with increased populatio
280、n from 2010 to 2020 and possibly more residential safety risks.Since ecological protection in south Sichuan and south Yunnan is quite important,forest fires may threaten biodiversity there.4.6 Risks caused by extreme weathers More severe typhoon threats in coastal areas,tropical cyclones affecting p
281、arts of Yunnan.Typhoons mainly hit coastal areas of Shanghai,Jiangsu province and Zhejiang province in the lower reach of the Yangtze River,possibly submerging coastal areas.Shanghai has high levee level to resist storm surges with medium and low intensities,but typhoons in extreme weathers are stil
282、l risky.Yunnan is partially hit by tropical cyclones landing on the South China Sea,reflected by disastrous weathers like strong wind and heavy rainfalls.Affected agricultural production in the middle reach of the Yangtze River by low-temperature freezing disasters.Low-temperature freezing disasters
283、 and snow disasters mainly hit Hubei,Hunan and other areas along the middle reach,some areas in Yunnan,Guizhou along the lower reach,and some in Anhui along the lower reach.Since high-quality agricultural production areas of the Middle-lower Yangtze Plain are in areas with low-temperature freezing d
284、isaster risks,it is necessary to have better abilities of agriculture to deal with risks.Wind hail-affected upper and middle reaches of the Yangtze River.Wind hails occur mostly in Chongqing,Yunnan and Guizhou,followed by Hunan and Jiangxi.Specifically,such areas include Dazhou City,Chongqing metrop
285、olitan area,Yibin City,Luzhou City,Bijie City,Liupanshui City,Qujing City along the upper reach in the border area between Sichuan and Chongqing,along with Changde City,Yueyang City,Yiyang City,Jiujiang City,Yichun City and Jingdezhen City along the middle reach.Among them,Chongqing,Changsha,Nanchan
286、g and other metropolitan areas are densely populated,with high risk of wind hail.Wind hail also hits high-quality agricultural areas in northeast Sichuan and north Hunan,triggering risks to agricultural production.26 4.7 Spatial characteristics and risk analysis of major disasters 4.7.1 Spatial char
287、acteristics of major disasters Floods and geological disasters caused by heavy rainfalls in the upper reach of the Yangtze River are the most prominent,with high frequencies,wide ranges and serious losses.Disasters like wind hails and low-temperature freezing disaster are also common in the area.Are
288、as around the Sichuan Basin,including Longmen Mountain,Daba Mountain and Wushan Mountain,often see mountain torrents,landslides,debris flows and other geological disasters caused by heavy rainfalls;In the middle of Sichuan Basin,represented by Chengdu Plain,heat waves and urban waterlogging are the
289、most common;In the Yunnan-Guizhou Plateau,mountain torrents,geological disasters,drought,low-temperature freezing disasters are common;And forest fires,mountain torrents and geological disasters often occur in Panxi of Sichuan and mountainous area of south Yunnan.Middle reach of the Yangtze River is
290、 flood-affected,with frequent droughts and low-temperature freezing disasters.Jianghan Plain is often hit by floods,droughts and low-temperature freezing disasters;Areas along the Yangtze River in the middle reach are often hit by heat waves,urban waterlogging and river floods.Dongting Lake Plain is
291、 usually hit by floods,droughts and low-temperature freezing disasters;Floods and waterloggings often occur in Poyang Lake Plain;While Nanling area is often struck by forest fires,landslides and other geological disasters.Coastal areas in the lower reach of the Yangtze River are greatly affected by
292、sea-level rise and typhoons.The Yangtze River Estuary faces rising sea-level and typhoon storm surges;Areas along the Huaihe River mainly face floods and droughts;Areas along the lower reach are often hit by floods and typhoons;Mountainous areas in south Zhejiang are often hit by mountain torrents,g
293、eological disasters and typhoons.Figure 4-14 Sub-divisions of major disasters caused by climate change in the Yangtze River Basin 4.7.2 Risk analyses of key areas Municipalities directly under the central government,provincial capital cities and their metropolitan areas have fast-growing population,
294、with high disaster risks caused by climate change.Chengdu,Chongqing and Changsha are often hit by heat waves and urban waterlogging;Guiyang and 27 Wuhan are often hit by floods,droughts,low-temperature freezing disasters;Nanchang,Hefei and Nanjing often see floods;Shanghai and Hangzhou often see typ
295、hoons,while cities in south Zhejiang are struck by mountain torrents and geological disasters.The population of the above regions and counties in the metropolitan area has generally gone up by more than 100,000 in recent ten years.Figure 4-15 Superposition analysis of disaster zoning and population
296、growth Agricultural production areas in the north of the upper,middle and lower reaches are at high risks of floods,droughts,low-temperature freezing disasters.Agriculture is widely distributed in Sichuan Basin,Hanjiang plain,areas along the middle reach,Dongting Lake Plain,Poyang Lake Plain and Hua
297、ihe River Basin,which are affected by floods,droughts,low-temperature freezing disasters,with higher agricultural industry risks under climate change.Among them,Sichuan Basin along the upper reach is mainly hit by short-term floods;Jianghan Plain and Lianghu Plain along the middle reach are key rice
298、 producers in China,which may be hit by low-temperature freezing disasters during flower stage of early rice booting in late May,and low-lying floods and waterlogging in summer,along with droughts in spring and autumn are likely to reduce agricultural production.Areas along the lower reach can be hi
299、t by floods and typhoons.Figure 4-16 Disaster zoning and superposition of high-quality agricultural areas and urbanized areasChengduChongqingGuiyangChangshaWuhanHefeiNanjingShanghaiJiaxing、Hangzhou、JinhuaNanchangProvincePrefecture-level cityDecrease 100 thousandDecrease 0-100 thousandGrowth 0-100 th
300、ousand Growth 100-500 thousandGrowth 500 thousandSichuan BasinHeat,waterloggingWestern PanzhihuaWildfire,flood and geological disasterSouthern Yunnan MountainsWildfire,flood and geological disasterNan Mountains Wildfire,geological disasterYunnan-Guizhou PlateauFlood and geological disaster,Drought,e
301、xtreme coldJianghan PlainDrought,extreme cold,floodMiddle reaches of Yangtze RiverHeat,waterlogging,floodDongting Lake plainDrought,extreme cold,floodPoyang Lake PlainFloodHuaihe River BasinFlood,droughtYangtze EstuarySea lever rise,typhoonSichuan Basin surrounding areaFlood and geological disasterS
302、outhern Zhejiang MountainsFlood and geological disaster,typhoonLower Yangtze RiverFlood,typhoonProvincePrefecture-level cityUrbanized areaMetropolitan areaPremium agricultural areaCounty 28 5.Resilience Strategies of the Yangtze River Basin in Response to Climate Change The safety and resilience of
303、urban and rural settlements along the Yangtze River basin is the key to cope with climate change and disaster risks at present,and it is necessary to improve long-term disaster prevention and adaptation capabilities,as well as to be more adequately prepared for short-term impacts of extreme weather.
304、Specifically,engineering measures and nature-based solutions(NbS)should be integrated to form a comprehensive safety and resilience strategy through four aspects:ecological protection,spatial optimization,facility construction,and emergency management.5.1 Strategies on improving resilience of the Ya
305、ngtze River Basin 5.1.1 Strategies on ecological protection Ecological protection strategy reduces risks from the source by reducing the frequency and intensity of disaster events and plays an important role in increasing carbon sinks and helping China achieve its“double carbon strategy”.Manage and
306、control ecological function areas and nature reserves.Multiple important ecological function areas are distributed in the Yangtze River Basin,and the implementation of strict“Ecological Protection Red Line”system and“Compensation for Environmental Damage”system can maintain and improve the ecologica
307、l level of important ecological function areas and nature reserves.The use of carbon sinks in nature reserves is encouraged to achieve carbon neutrality and carbon sinks in nature reserves is further explored to meet the relevant requirements and conditions of carbon emissions permit trading for car
308、bon sink additionality and cooperation so as to improve the efficiency of ecological compensation.4041424344 Figure 5-1 Spatial distribution of ecological protection red line of the Yangtze River Basin(left)as well as important ecological function areas and nature reserves(right)Strengthen the compr
309、ehensive governance of water and soil conservation.The Yangtze River Basin is one of the most serious areas of water and soil loss in China,and climate change will create more pressure on water and soil loss.We should delineate and announce by law the areas with serious water and soil loss and fragi
310、le ecology as soon as possible,scientifically promote the comprehensive governance of the areas with serious water and soil loss,improve the monitoring service capacity and the problem detection,and strengthen the supervision of industrial soil and water conservation.Comprehensive governance can ado
311、pt a series of technical methods,including:intercepting and draining slope runoff and interflow,and storing a certain amount of water in the rainy season;returning farmland to forest and grass on steep slopes,and greening barren mountains and hills;promoting the projects of changing slopes into terr
312、aced fields,soil conservation tillage,and other soil conservation measures on slow slopes;reasonably 29 deploying small intercepting and draining storage projects and field roads on slopes during planting forestry and fruit;configuring mutual cooperative engineering measures to control the developme
313、nt of channel erosion.In general,the foundation of scientific research on soil and water conservation in the Yangtze River Basin is still weak,and current research should focus on the critical areas such as soil and water mechanism and water-sand dynamics of the river basin under climate change.4546
314、47 5.1.2 Strategies on spatial optimization The land use and spatial layout of urban and rural settlements should not be based solely on development efficiency but should also fully consider the multiple objectives such as safety,livability,and ecology.The spatial optimization strategy can avoid dis
315、aster impact space and reduce disaster risks through scientific urban land site selection and achieve symbiosis with disasters and adaptation to disaster development by increasing disaster tolerant cushion space.In the selection of the spatial optimization strategies,emphasis should be laid on the s
316、election and implementation of nature-based solutions.Establish a strict disaster safety assessment system for site selection of a new city and a new district.The mainstream and major tributary areas of the Yangtze River are affected by river flood and thus they are closely related to urban site sel
317、ection.Where involving off-site reconstruction after major earthquakes or geological disasters,the site selection of new cities and relocation sites should be subject to strict disaster safety assessment and full scientific appraisal,and safe sites should be used as far as possible to reduce disaste
318、r risks by using natural conditions and reduce site exposure from the source.The development of waterfront and coastal area must be based on scientific safe defense system planning and vertical site planning;The site selection and construction methods by filling rivers and lakes,cutting mountains an
319、d filling valleys should be strictly limited.Control the population layout of dwelling and employment and land development intensity.Prevent excessively high population density from leading to expanded disaster losses.There are still a large number of residential areas in some provincial capitals in
320、 China where the population density is above 20,000 people/square kilometer and should continue to be reduced.Implement the group layout model of urban space.Optimize and improve the layout of urban land use which has neglected safety and ecology in the rapid development,change the big pie layout to
321、 group layout,and introduce the large-scale green belt,green wedge and wind corridor,which can not only mitigate the heat wave and heavy precipitation disaster impact,but also provide more space for the city to avoid disasters.“Returning land to river”to leave space for river.The spatial organizatio
322、n of river waterfront areas is critical for long time scale.In respect of the natural and historical water systems the historical and flood discharge river channels occupied by industrial land and housing development shall be returned to the rivers for floodwater drainage and storage.At the same tim
323、e,natural riparian land should be preserved as much as possible to provide strategic flexibility for future suitability initiatives and increase the safe resilience of the river basin.This concept,proposed by Netherlands,summarizes a solution with“retaining,storage,and drainage”strategy in wide prac
324、tice to create a resilient buffer ability of the river channel against precipitation by modifying the river channel.The main technical measures for“returning land to river”include embankment moving backwards,restoration of river floodplains,and reduction of the riverbed.Delineate disaster risk areas
325、 and leave disaster tolerance space.The cushion space for disaster tolerance is delineated according to the scope and intensity of disaster impact,especially in risk areas of torrential floods,earthquakes,landslides,mudslides and other mountain disasters;If necessary,the relocation project in high-r
326、isk areas is implemented,and the construction of disaster prevention 30 engineering facilities is strengthened at population accumulation points;At the same time,the disaster monitoring and early warning as well as emergency response system of disaster risk areas and surrounding areas is perfected,a
327、nd the evacuation of people in the risk areas is timely guided.5.1.3 Strategies on facilities construction Disaster defense system and infrastructure construction are the basic guarantee of urban safety resilience,and the long-standing inertia of local governments that emphasize development rather t
328、han safety and focus on over-ground rather than the underground must be changed fundamentally.In the construction of facilities,the engineering thinking of individual projects should be avoided.Instead,the emphasis should be placed on implementing the systemic disaster defense.Special attention shou
329、ld be paid to the construction of disaster defense system,sponge city resilience adaptation system,emergency supply guarantee system,and lifeline facility system for urban and rural settlements in the river basin.Strengthen the construction of systematic and engineering disaster defense systems.On t
330、he basin scale,the reinforcement of embankments is organically combined with the construction of flood storage areas and the joint optimal scheduling of reservoirs in the main stream and tributaries of the Yangtze River to form a more complete“embankment+reservoirs+floodplain”comprehensive flood con
331、trol system of the Yangtze River,so as to realize the prevention,blocking,evacuation,drainage and interception of floods;Great importance should be attached to the overall plan and coordination of flood control capacities of cities and basins so as to avoid the risk of urban disasters caused by diff
332、erent flood control standards in the basin.At the level of urban and rural settlements,the actively adaptive disaster prevention and mitigation measures combining with“blue,green,and gray”facilities should be taken as much as possible to form a comprehensive disaster prevention and mitigation strate
333、gy.Promote the construction of sponge cities.Reduce emissions at source first,build green facilities,enhance the“resilience”of the city in response to climate change and storm disasters,and promote the formation of an ecological,safe,healthy,and sustainable urban water cycle system.According to the rainfall characteristics,flooding problems,and water resources problems of specific cities along the