Field Infiltration Test Of Seasonal River And Numerical Simulation Study About Laboratory Experiment On The Unsaturated Zone

Most of the northern part of China has a large population and a large population of water for production and living,and water resources per capita is extremely short in this area,which belongs to the arid and semi arid area.Seasonal rivers are common in arid and semiarid areas.Dagu River is the main water source of Qingdao City,which belongs to the seasonal river.The water level of the Seasonal rivers rise and fall quickly in the flood season is closely related to river seepage.The study on the leakage situation of Dagu River will provide a scientific basis for the further study of the water flow and groundwater level in the relationship between time and space,and then provide the scientific basis for the management of water resources in Dagu River Basin,also provide reference for other seasonal river water management.This paper takes Dagu River as the research object.First of all,the Dagu River Basin meteorological phenomena and hydrological geology and geomorphology were investigated.Secondly,particle size distribution,dry bulk density,soil particle density,porosity and permeability coefficient of the sand samples were determined by laboratory test.Thirdly,we selected three representative field test sites through the exploration of the upstream,midstream and downstream of the Dagu River,to carry out one-dimensional vertical unsaturated infiltration and two-dimensional lateral unsaturated infiltration tests,and analyze the law of soil moisture migration.Finally,we use the FEFLOW software to simulate the process of indoor one-dimensional vertical unsaturated infiltration and two-dimensional lateral unsaturated infiltration,and verify the rationality of the model by comparing the simulated and measured values.The main conclusions of this paper are as follows:(1)Based on the sand samples of the selected three field test sites,Sand samples of the upstream,midstream and downstream was identified as coarse sand,medium sand and fine sand by analyzing of particle size distribution,and dry bulk density,soil particle density,porosity and permeability coefficient were determined.(2)In the three selected field test site,one-dimensional vertical infiltration experiments of vadose zone of two groups were carried out in each field test site under fixed head,by comparing and analyzing infiltration test,the smaller the initial water content,the faster the rate of infiltration,the shorter time to reach the sensor under the same test field and depth;with the increase of depth under the same test field,the change of water content decreases progressively and the time to reach saturation is extended in turn;when the sand initial water content of same depth is close,and the sand water infiltration rate of the upstream,midstream and downstream decreases in turn;from the whole point of view,when the sum of the initial water content of each layer is similar under the sand of the same test field,the smaller the initial water content gap,the shorter the time to reach the stable infiltration.(3)In the three selected field test site,one-dimensional lateral infiltration experiments of vadose zone of two groups were carried out in each field test site under fixed head,by comparing and analyzing infiltration test,the smaller the initial water content,the faster the rate of infiltration,the shorter time to reach the sensor under the same test field and depth;when the sand initial water content of same depth is close,and the sand water infiltration rate of the upstream,midstream and downstream decreases in turn;from the whole point of view,when the sum of the initial water content of each layer is similar under the sand of the same test field,the smaller the initial water content gap,the shorter the time to reach the stable infiltration.(4)one and two dimensional unsaturated seepage experiment of the laboratory was simulated by using the groundwater numerical simulation software FEFLOW,compare the simulation value with the measured values,the results show that the simulation result and the actual value basically tallies,so the model is basically reasonable,and simulating water transport with FEFLOW in vadose zone is feasible,meanwhile,the model provides reference for simulating the water movement in the unsaturated zone of Dagu River Basin.