Study Of Eco-Hydrological Response To Climate Change And Land Use/Cover Changes In The Amur River Basin

In recent decades,the global water cycle and water resources are under enormous pressure from factors such as high-intensity human activities and intensifying climate change.Extreme rainfall,droughts,floods and other extreme events are increasing in frequency and intensity,and global change factors such as climate change,population growth and urbanization are changing the spatial and temporal distribution of water resources while making the conflict between supply and demand of water,food and energy increasingly severe.The sustiability issues related to water problems have become a key factor constraining national and regional social-economic development.As one of the regions with the most significant global climate change,the Chinese part of the transboundary Amur River Basin is the main food-producing region in China,and an in-depth study of the impact of global change on the ecology and hydrology of the Amur River Basin is of great significance to the management and control of water resources in the basin,which is closely related to the ecological security,water security and food security of the Amur River Basin.Therefore,this study took the Amur River basin above the Komsomolsk hydrological station(about 94% of the total area of the Amur River basin)as the study area to analyze the impact of climate change and land use/cover change on the ecohydrological processes in the basin: first,the spatial and temporal changes of climate and substratum in the basin from 1980 to 2013 were analyzed based on remote sensing data and actual meteorological station data;second,we simulated the hydrological processes in the Amur River basin based on the SWAT hydrological model,and quantitatively analyzed the effects of climate change and land use/cover change on the hydrological processes such as surface runoff,lateral flow,groundwater flow and blue and green water flow in the basin by setting different simulation strategies,and explored the spatial and temporal relationships between vegetation characteristics and climate,anthropogenic and hydrological factors in the basin.Thirdly,combined with the analysis results of climate and land use change characteristics of the basin,the impact of a single climate factor or land use type on the eco-hydrological process of the basin was revealed.Finally,based on the Representative Concentration Pathways(RCPs)of emission scenarios established by the Coupled Model Comparison Program Phase 5(CMIP5),the response characteristics of future hydrological processes in the Amur River basin under different RCP scenarios were predicted.The main research results and innovations of this study are as follows.(1)Based on the basin long-time measured meteorological station data,multiperiod land use data and other information,this paper revealed the characteristics of changes in climate elements,land use and vegetation parameters in the Amur River basin to characterize and quantify the climate change situation and intensity of human activities in the basin,and to pave the way for effective analysis of the effects of climate change and human activities on the ecohydrological processes in the basin.The results show that the climatic tendency rate of the annual precipitation and average temperature of the basin is 8 mm/10 a and 0.3°C/10 a,respectively,with an overall increasing trend,and precipitation underwent a significant abrupt change around 1996-1998;the wetland area changed dramatically around 2000,and the wetland area declined significantly during this period and was largely converted to agricultural land(about 24.49%);the vegetation parameters of LAI,FVC and GPP in the Songnun Plain in general and decreasing in Mongolia part of the watershed.For LAI and FVC,the most significant local spatial autocorrelation changes were identified on the Sanjiang Plain,and the lowlow agglomeration in the Sanjiang Plain continued to decrease.(2)Based on various types of databases such as hydro-meteorological data,soils,and land use in the Amur River Basin,this paper used the distributed hydrological model SWAT model to reveal the response mechanisms of ecohydrological processes in the Amur River basin under the influence of global change based on the settings of different simulation scenario strategies.The study reveals that for surface runoff,lateral flow,groundwater runoff in the watershed,the changes in land use types of crop and wetlands have the greatest impact,so the interconversion of crop and wetlands,such as wetland reclamation,can have a huge impact on the hydrological processes in the watershed.(3)Based on the simulation results of ecohydrological processes in the Amur River basin during the historical period of SWAT model,we analyzed the characteristics of blue and green water changes in the Amur River basin,and combine different simulation results of scenario strategies to quantitatively assess the impact and contribution of climate change and land use/cover change on blue and green water changes in the Amur River basin,and reveal the impact of single climate elements or land use types on blue and green water in the Amur River basin.For blue and green water,summer precipitation and summer average daily temperature are the climatic factors that have the greatest influence on blue and green water.Compared to winter,summer climate factors have a greater impact on blue and green water.The most important predictor affecting blue and green water is wetland,followed by crop.(4)Based on the climate data of the Amur River basin for the next 30 years under the RCP scenarios of CMIP5 model,we analyzed the future climate change characteristics in the basin,predicted the future trends of hydrological processes and blue and green water in the Amur River basin under different RCP scenarios,and analyzed the response characteristics of each hydrological element and blue and green water in the basin to climate change under different climate change conditions.The study shows that the blue water flow in the basin will decrease under RCP2.6 and RCP6.0 scenarios and increase under RCP8.5 scenario,and the trend is not significant.Green water flow in the basin tends to increase under RCP2.6,RCP6.0 and RCP8.5scenarios,with significant trends at RCP6.0 and RCP8.5.Green water flow in most months is ranked as RCP8.5 > RCP6.0 > RCP2.6 in all three scenarios.This study comprehensively assesses and predicts the impacts of climate change and land use/cover change on ecohydrological processes in the Amur River Basin from both historical periods and future scenarios,from multiple perspectives such as river runoff,hydrological components,and blue and green water,based on ground data and remote sensing monitoring data and other multi-source information,and provides a scientific basis for making decisions on water resources management configuration basins and ecosystem protection and reconstruction in the Amur River Basin.This study provides a scientific basis for making decisions on water resources management in the Amur River Basin and ecosystem protection and reconstruction.