Study On Immersion Control Measures Of Plain Reservoir

The plain reservoir valley is wide,the terrain is flat,the Quaternary cover is thick.Water storage in the reservoir may lead to high groundwater level in the lower reaches of the reservoir,shallow groundwater burial,and unsmooth drainage,thus forming an immersion disaster.The occurrence of immersion disasters can lead to problems such as soil salinization,swamping,and instability of building foundations,and its adverse effects seriously restrict people's lives and property.This paper takes the water storage of Shifosi Reservoir as the background for the immersion in the lower reaches of the right bank,and uses Visual MODFLOW software to establish the groundwater mathematical model,evaluates the degree of reservoir immersion,discusses the immersion and its treatment measures,and introduces different immersion measures.The principle of boundary treatment is to calculate the change in its governance effect.The main research results are as follows:(1)According to the collected precipitation,evaporation,soil type,hydrogeological conditions,topographical structure,recharge infiltration and other information in the lower reaches of the right bank of the Shifosi Reservoir,the numerical model of unsteady flow groundwater was established by Visual MODFLOW software,and the hydrological parameters were calculated.By checking and adjusting,the flow field distribution,the fitting degree of groundwater level and the error precision are analyzed to establish a groundwater model that can reflect the real characteristics of groundwater movement characteristics and dynamic changes in the study area.(2)According to the“Water Conservancy and Hydropower Engineering Geological Survey”(GB50487-2008),the immersion evaluation standard was established.According to the soil sampling experiment results in the study area,the critical depth of groundwater for severe immersion,moderate immersion and mild immersion in the study area was determined to be 1.85m.2.5m,2.9m.It is concluded that the area of severe immersion area in the study area is about 3.09km~2,accounting for 42.3%of the total area of the study area,the area of moderate immersion area is about 0.58km~2,accounting for 7.95%of the total area of the study area,and the area of the light immersion area is about It is 0.27km~2,accounting for 3.74%of the total area of the study area,and the total area of the immersion area is 3.94km~2,accounting for 54%of the total area of the study area.(3)Using the established groundwater model,the immersion treatment effect of the drainage ditch,the decompression well and the pumping well on the study area was simulated by numerical calculation.The results of the study show that the single-stage drainage ditch has a small impact range,which is insufficient to meet the immersion control needs in the study area.The multi-stage ditch has a significant effect on the drainage and decompression of the single-stage ditch,and the area of the immersion area is reduced by 45%to 80%.When the ditch depth is 3m and the groove spacing is greater than 200m,the immersion and anti-pressure effect is better,which is the optimal solution for the drainage ditch.The effect of the relief well measures on the immersion treatment in the severely immersed area is more obvious,the moderate immersion area is moderate,and the mild immersion area is weak.The relief well can effectively reduce the immersion disaster in the severely immersed area to a certain extent,and can basically guarantee the production safety in the farmland area.The immersion area is reduced by 30%to 70%after the pumping well is laid,and the immersion reduction effect is weakened with the increase of the well spacing.Through calculation,the pumping well scheme can adopt a well spacing of 500m and a pumping rate of 2000m~3/d as the best treatment plan.