Analysis And Simulation Of Groundwater Temporal And Spatial Dynamic Changes In Shenwu Irrigation Area Of Hetao Irrigation District Based On Environmental Changes

Taking the Shenwu Irrigation Area,an important pilot project of the Hetao Irrigation District’s water-saving renovation project,as the research object,adopting the monitoring method of regional well deployment,using classical statistics and geostatistics theories,studying the large-scale irrigation area and the small-scale conditions of different ecological landscapes,The spatial variability and temporal and spatial distribution of groundwater depth and water quality before and after water-saving transformation.Select natural and human factors to clarify the main driving factors influencing the changes of groundwater depth through gray correlation method.Build multiple linear regression models,multivariate CAR models,gray GM(1,1)residual models,one-time exponential smoothing models and ARIMA(1,1,1)models for groundwater depths to provide a long series of groundwater depth predictions in accordance with.The main research conclusions are as follows:1.The annual groundwater depth of the irrigation area is 2.770 m,showing an increasing trend year by year,from 2.646 m before the water-saving transformation to 2.835 m.The annual salinity is 2389.071mg/L,showing a trend of first decreasing and then increasing,increasing from 2568.349mg/L before transformation to 2671.433mg/L.The nugget coefficient of groundwater depth has changed from a moderate correlation of 44.692%before the transformation to a strong spatial correlation of 16.084% after the transformation.The nugget coefficient of groundwater salinity increased from 42.778% before the transformation to 44.577% after the transformation,both of which showed a medium spatial correlation.The initial stage of the transformation had a greater impact on groundwater salinization.2.The spatial pattern of the buried depth of the groundwater in the irrigation area is distributed in a local funnel.The area of 1～2m in the buried depth interval is 7%,the area of2～3m is the largest 51%,the area of 3～4m is 36%,and the area of 4～5m is The proportion is 5%,the proportion of area larger than 5m is 1%;The spatial distribution of groundwater salinity is in a high-low-high band from southeast to northwest.The water quality is mainly brackish water,and the area ratio is reduced from 62.648% before the transformation to58.051%.3.The average buried depths of groundwater in desert areas,saline-alkali areas,channels and woodlands are 8.102 m,1.588 m,3.172 m,and 2.860 m,respectively,and the average salinity values are 925.22mg/L,1349.230mg/L,and 832.528 respectively.mg/L,1010.362mg/L,The overall variation of groundwater depth beside the lake is relatively small,with an average value of 3.204 m,and an average value of 1077809mg/L of salinity.After the renovation,the depth of groundwater and the overall degree of salinity increased compared with that before the renovation.4.The first three leading factors that have a greater impact on changes in groundwater depth are groundwater extraction,Yellow River water diversion,and precipitation,with correlation degrees of 0.9982,0.9974,and 0.9966,respectively.5.Use the first three dominant factors of groundwater depth to fit the burial depth of the irrigation area for many years.The models with better effects are the CAR model and the MLRM model.Under the condition of constant precipitation,groundwater extraction increases by 3%,5%,and 10%,and the Yellow River diversion volume decreases by 3%,5%,and 10%,the CAR model is used to predict the depth of groundwater to be 1.945 m,respectively,1.950 m and 1.960 m.