| Global warming due to natural and human factors has increased the risks of dramatic changes in the surface earth system on which humans survive.As a result,the problems such as extreme weather,Arctic methane release,permafrost degradation and novel viruses as well as the negative effects of global environmental changes arising accordingly have repeatedly foretold the possibility of uncontrollable climate in the Anthropocene.In view of this,regional climate change and hydrological response,one of the frontier research issues in the field of global change,was identified in this research as the key scientific issue.And the Amur River Basin,a typical basin with strong response to global change in cold mid-high latitudes,was selected as the research area.Its purpose was to reveal the evolution law and trend of important terrestrial hydrological cycle patterns and processes in this region under the changing environment and provide a scientific basis for regional mitigation and response to global change.This research completes the following contents and innovations:First,based on multi-source spatiotemporal observations and systematic analysis,this research identified and revealed the basic characteristics of major variations in the features of climate,hydrology and underlying surface in the Amur River Basin.It laid the foundation for further research on hydrological processes and wetland distribution dynamics in the basin in the context of climate change.In addition,an important requirement was proposed,namely the development of a distributed hydrological model applicable to the cold mid-high latitudes in the Amur River Basin,and this was also one of the major objectives of this research.Therefore,on the one hand,it should attach importance to the long-term historical runoff series of the basin and give the simulation results of more elaborate spatiotemporal evolution process of various terrestrial hydrological fluxes and storages;on the other hand,it should support the quantification,evaluation and estimation of changes in hydrological cycle pattern and process under the dual stress of complex underlying surface and climatic factors.Second,in view of the new progress of parameterization,the distributed hydrological model ESSI was updated and improved as required to strengthen its accurate representation of grid and sub-grid hydrological processes,reduce its uncertainty and use the rapidly developing high-tech means as much as possible.The new version ESSI-3 developed achieved elaborate simulation of terrestrial hydrological cycle processes in the whole Amur River Basin.According to the model applicability evaluation results based on different scales and data,ESSI-3 can effectively simulate the spatiotemporal evolution of key hydrological processes in the Amur River Basin,such as runoff,evapotranspiration,terrestrial water storage,and groundwater storage.In addition,this research systematically introduced the acquisition methods of parameters such as surface meteorology,soil,vegetation,terrain and water system required to drive ESSI-3.It solved the difficulty to acquire driving parameters of largescale model and innovatively proposed a tool for downscaling weather data from largegrid reanalysis products(ESDH)and a new method system for climate model data uncertainty evaluation as well as data correction,fusion and downscaling.Third,this research innovatively proposed a new wetland distribution index,Climate-Soil-Terrain Index(CSTI),based on the wetland occurrence and development mechanism and effectively proved the superiority of the new index in the representation of wetland distribution with the help of the wetland classification accuracy evaluation method and maximum entropy model.In addition,based on the TOPMODEL principle,this research effectively connected CSTI with ESSI-3 through the three-parameter power exponential function method to build a dynamic wetland module.According to the application results,the module can effectively reproduce the spatial distribution patterns and seasonal dynamic characteristics of wetlands in the Amur River Basin.Forth,focused on the response mechanism and trend estimate of hydrological process and wetland distribution in the Amur River Basin under the changing environment and based on the model ESSI-3 coupled with the dynamic wetland module,this research analyzed in depth the characteristics and mechanism of spatiotemporal response of 12 key hydrological process components in the Amur River Basin in the past 20 years to the changes in the major features of climate and underlying surface,as well as the trend of changes in these hydrological processes and wetland distribution under different climate change scenarios in the next 30 years.According to the research results,on the one hand,the response of different hydrological process components to environmental changes presented complex mechanisms and high spatial heterogeneity,but there was still a law and the research identified the dominated factors affecting the changes in different hydrological processes.On the other hand,the trend of the hydrological process components in the future period indicated that in the future complex context of climate changes,the key hydrological processes and wetland distribution in the basin will present spatially a changing pattern of continuation,aggravation or reversion.These results provided important support for scientific and effective responses to future climate change in the Amur River Basin. |
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