Research On Ecosystem Soil Conservation Service Of Jinghe River Basin Based On Land Use Simulation

The Loess Plateau is the main source of sediment in the Yellow River,with serious soil erosion and fragile ecological environment,which severely hinders the sustainable development of ecology,economy and society.Soil conservation service is one of the important regulation services of ecosystem services,which is of great significance to the ecological security of the Loess Plateau and has become the focus of attention.However,most studies have explored the status quo of ecosystem soil conservation service,and lack of scenario predictions for future ecosystem soil conservation service.Therefore,this paper takes the Jinghe River Basin in the hinterland of the Loess Plateau as the research area,coup ling the Artificial Neural Networks(ANN)with Cellular Automata(CA)to construct the ANN-CA land use simulation model,and with help of the Soil and Water Assessment Tool(SWAT)to simulate ecosystem soil conservation service in 2000-2020 and 2021-2040 under different climate scenarios(RCP4.5/RCP8.5),explore the characteristics of the temporal and spatial changes of soil conservation service,and provide scientific support for the future ecological construction of the basin.The main conclusions are as follows:(1)The simulation accuracy of the constructed ANN-CA model meets the requirements.When the T=0.8,α=2,and b=1.2,the overall accuracy rate of the 2020 Jinghe River Basin land use data simulated by the model is 89.39%,and the kappa coefficient is 0.9675.At the same time,the accuracy of the six types of land use data also reaches 80%,and the land use simulation effect is good.(2)According to the predicted results of land use in the next 10 years,compared with 2020,the land use type area change of the basin in the future 2030 is:the area of cultivated land will decrease by 421.32km~2,which is the land use type with the largest decrease;The area of forest and grassland will increase by 6.25km~2 and 208.48km~2,respectively;With construction land as the center,the area has increased by 263.74km~2,which is the largest increase in land use type;The water and unused land will decrease by 14.30km~2 and 42.85km~2,respectively.(3)From the perspective of soil conservation from 2000 to 2020,the monthly change trend of soil conservation service in the basin is consistent with rainfall,with the largest in August.Moreover,the inter-annual change is large,showing a fluctuating increasing trend,with a growth rate of 2.76×10~6t/a,and an average soil conservation amount of 2.98×10~8t.There are obvious regional differences in the spatial distribution of soil conservation service in the basin.The amount of soil conservation per unit area is "highest in the west,higher in the east,lower in the middle and south,and lowest in the north".(4)From the perspective of soil conservation from 2021-2040,the inter-annual change of soil conservation service under the RCP4.5 scenario shows a fluctuating increase,with a growth rate of 6.95×10~5t/a,while under the RCP8.5 scenario,the fluctuation decreases,the deceleration is 1.44×10~6t/a.There are complexities in the amount of soil conservation in the basin under the two future climate scenarios.The multi-year average soil conservation under the RCP4.5 scenario is 1.67×10~8t,and the RCP8.5 scenario is 1.77×10~8t,which means that the soil conservation under the RCP8.5 scenario is slightly more than that in the RCP4.5 scenario.The spatial distribution of soil conservation per unit area in the RCP4.5 and RCP8.5 scenarios is "increased from northwest to southeast".(5)From the perspective of the basin soil conservation rate,the multi-year average soil conservation rate of the Jinghe River Basin from 2000 to 2020 is 82.54%,and the multi-year average soil conservation rate of the basin under the RCP4.5 scenario and RCP8.5 scenario from 2021 to 2040 are 84.67%and 84.80%,respectively.That is,the soil conservation rate is"RCP8.5>RCP4.5>2000-2020" under different time periods and different climate situations.There are differences in the soil conservation rate of each land use type under the two climatic scenarios from 2000 to 2020 and from 2021 to 2040,which are as follows:water>construction land>forest>grassland>cultivated land>unused land.