Research Of Water Conservation Services In National Key Ecological Function Areas Based On Multi-Source Data

Based on the multi-source data of ground observation,meteorology,remote sensing and GIS from 2000 to 2015,this suty modified the parameters of the PT--JPL evapotranspiration model and verified by the ground.The water conservation and service water conservation index were calculated based on the principle of water balance,and the refined and quantified water conservation services assessment method system developed form a dynamic analysis of the ecosystem landscape,water conservation,and water conservation service index.Based on this method system,taking 8 water conservation key ecological function areas in China as the research object,this paper analyzed the dynamic changes of ecosystem structure s,estimated the ecosystem evapotranspiration,water conservation services,revealed the spatial temporal dynamic changes of the ecosystem landscape,evapotranspiration,and water conservation services and their influencing factors in the past 15 years.Meanwhile,the results were compared with the water conservation index adopted by the current ecological environment assessment method and applied to the assessment of the importance of water resources conservation capacity at county scale in China,and further developed a water source conservation index assessment method based on long-term serial data and based on ecosystem services.The main conclusions are as follows:(1)This sutdy collated monitoring data of China Meteorological Administration,MODIS satellite remote sensing data,remote sensing interpretation of land use/cover data and ground observation flux data.Based on the space weather data interpolation methods,remote sensing data processing methods,and flux data processing methods,this research formed meteorological data(including precipitation,temperature,net radiation,etc.)and remote sensing data(including normalized vegetation index and enhanced vegetation index)with a time respulution of 8d and spatial resolution of 1 km during 2000 to 2015,multi-phase land use/cover data with a spatial resolution of 1 km,and observation data consisting of flux observations at 127 stations per year for 45 stations.There data laid the foundation for the ecological assessment of key ecological function areas for water conservation.(2)Based on ground-based observation,meteorology,remote sensing,GIS and other multi-source data,a refined and quantified water conservation service evaluation method system consisting of dynamic analysis of ecosystem pattern,estimation of water conservation,and evaluation of service water conservation index was developed.This study corrected soil evaporation water limiting factor,plant growth optimum temperature,transpiration water limiting factor,and canopy extinction coefficient of the internationally renowned PT-JPL model.The results of modified PT-JPL model were compared with measured surface data,the determination coefficient reached 0.68,and the RMSE was 161mm/m2/y,significantly better than the international mainstream MOD 16 product,with a determination coefficient of 0.49 and RMSE of 218.16 mm/m2/y,which improves the applicability and estimation accuracy of the PT-JPL model in China.The simulation results show that the average evapotranspiration of water conservation ecological key function areas has evident spatial variability in the past 15 years,and the overall trend decreases from southeast to northwest;the time trend is basically stable,and only the Sanjiangyuan meadow wetland ecological function area is significantly reduced.The ecological function areas where annual precipitation is higher than 400 mm/yr are mainly affected by net radiation,and the ecological function areas with annual precipitation below 400 mm/yr are mainly affected by precipitation.(3)Based on the results of the comprehensive dynamics of ecosystem dynamics and the transfer matrix method,it was found that the ecosystem structure of water conservation ecosystems has basically remained stable in the past 15 years.Overall ecological dynamic attitude was only 0.69%.Among them,wetland dynamics was the most significant,with an average annual growth rate of 2.9%and a significant increase of 41%in the area of construction land.(4)Based on the Sen trend analysis method and the Mann-Kendall significance test method,the temporal and spatial characteristics of water conservation of water conservation-type key ecological function areas in the past 15 years were systematically analyzed.The results show:the water conservation showed obvious spatial variability,and the overall trend also decreases from southeast to northwest;the time trend is basically stable,strongly influenced by climate change,and significantly positively related to precipitation,and affected by evapotranspiration and vegetation growth at the same time.(5)Based on the differences in natural endowment of different ecosystems in different regions and long-term continuous data sets,this study established a scientific ecological assessment reference,and first to propose a normalized water conservation index based on ecosystem services at the pixel scale,in order to eliminate the impact of regional natural endowment differences on water conservation capacity.The normalized water conservation index was compared with water conservation and structural water conservation indices and found significant differences in the spatial and temporal patterns,trends analysis,and importance assessment of water conservation.The resultscould provide support for China’s strategic transformation from "increasing the size of the area" to "maintaining the capacity of ecosystem services based on the area of the area" for the realization of ecosystem management and provide new ideas for the ecological supervision of ecological environment evaluation and the transformation of ecological service assessment and the delineation of ecological red lines.