Study On Soil Moisture Characteristics Of Regional Farmland And Its Effect On System Resilience

Hongxinglong Administration is located in the south-central part of the Sanjiang Plain.Its ecological and environmental conditions are suitable for agricultural development.It is an indispensable grain reserve base and a commodity grain production base in China.However,with the development of economy,Hongxinglong Administration has over-developed rice planting,resulting in a series of water environment and ecological problems,such as groundwater overexploitation,water shortage,soil degradation,and so on,which poses a serious threat to the local industrial and agricultural production and the living environment of residents.Taking the 12 farms in Hongxinglong Administration as examples,the soil moisture of regional farmland was monitored,extended and forecasted,the resilience evaluation index system for regional agricultural water and soil resources composite system considering soil moisture was constructed,the resilience measurement of regional agricultural water and soil resources composite system was completed,the resilience driving mechanism of regional agricultural water and soil resources composite system was analyzed,and the future evolution pattern of resilience for regional agricultural water and soil resources composite system considering the soil moisture,precipitation and groundwater depth was studied.This series of studies provided theoretical support for the resilience construction path of regional agricultural water and soil resources composite system of Hongxinglong Administration.The main research contents and results are as follows:(1)According to the partial least squares method(PLS),the regression equation of soil moisture was established by using the soil moisture monitoring data and related hydrological data of Hongxinglong Administration in 2017.At the same time,combined with the previous hydrological data,the established partial least squares regression model(PLSR)was used to extend the soil moisture,and draw the spatial and temporal variation map of the soil moisture of Hongxinglong Administration in 2013-2017.The results showed that the overall soil moisture of Hongxinglong Administration has a downward trend,with soil moisture in the eastern region being higher,followed by the western region,and soil moisture in the central region is lower.(2)According to the characteristics of the agricultural water and soil resources of the Hongxinglong Administration,and referring to the previous studies,the Driving forces-Pressure-State-Impact-Response(DPSIR)model was used to construct the primary resilience evaluation index system of agricultural water and soil resources composite system.The SPSS tool was used to screen the primary selection indicators according to the minimum mean square error method and the maximum uncorrelated method.Finally,14 indicators such as annual precipitation,water production coefficient,pesticide application per unit of cultivated land area,fertilizer application amount per unit of cultivated land,energy consumption of 10,000 yuan GDP,agricultural output value as a proportion of GDP,agricultural investment as a percentage of total investment,per-capita net income,air temperature,annual evaporation,soil moisture,groundwater depth,total investment in water resources and unit area grain yield were selected as the evaluation index for the resilience of the agricultural water and s oil resources composite system of Hongxinglong Administration.(3)According to the established resilience evaluation index system of agricultural water and soil resources composite system,this study adopted the projection pursuit model(SA-PSO-PP)based on simulated annealing and particle swarm optimization algorithm,the projection pursuit model(PSO-PP)based on particle swarm optimization and the projection pursuit model(ICSO-PP)based on the improved chicken swarm optimization measure d the resilience of the 12 farms of the Hongxinglong Administration in 2013-2017.Based on the stability and reliability of the evaluation results,the projection pursuit model based on simulated annealing and particle swarm optimization was selected as the optimal measure method for resilience of regional agricultural soil and water resources composite system.(4)According to the SA-PSO-PP model,combined with Arc GIS spatial data analysis technology,the temporal and spatial variation distribution maps of the resilience of Hong xinglong Administration were drawn.On the time scale,the resilience of the agricultural water and soil resources composite system of the Hongxinglong Administration has shown a downward trend.On the spatial scale,the resilience of the Hongxinglong Admi nistration is stronger in the eastern region,second in the western region,and weaker in the central region.(5)According to the principal component analysis method,the resilience driving mechanism of the agricultural water and soil resources composite system of each farm was analyzed.The results showed that annual precipitation,per-capita net income,agricultural investment as a percentage of total investment,soil moisture,groundwater depth have the greatest impact on the resilience of regional agricultural water and soil resources composite system,which are the main driving factors.(6)According to the characteristics of soil moisture time series,this study propose d a nonlinear combination forecasting model(EMD-PSO-ELM)based on empirical mode decomposition(EMD)and particle swarm optimization(PSO)optimized extreme learning machine(ELM).The EMD-PSO-ELM model was applied to the soil moisture forecast of Hongxinglong Administration.The results showed that the model has achieved good prediction results.At the same time,the EMD-PSO-ELM model was applied to the prediction of precipitation and groundwater depth,and it also achieved good prediction results.Finally,the soil moisture,precipitation and groundwater depth prediction data of Hongxinglong A dministration from 2018 to 2021 were obtained.(7)According to soil moisture,precipitation and groundwater depth prediction data,the SA-PSO-PP model was used to obtain the future evolution of the resilience of Hongxinglong Administration from 2018 to 2021,while other evaluation indicators remained stable.Combining with the general situation of water and soil resources,the present situation of resilience,the driving mechanism and the future evolution trend of resilience,this study put forward the path about resilience construction of the water and soil resources composite system of Hongxinglong Administration,which can provide decision support for the sustainable development of Hongxinglong Administration.