A Study On Calculation Of The Quantity Of Reverse Percolating Water Abstraction From Beneath Riverbed

Exampled by the project of Reverse Percolating Water Abstraction from BeneathRiverbed in Baishi reservoir of Beipiao, Liaoning province. In this paper, according tothe basic principle of the seepage mechanics with pores,the shape of the seepage fieldwere analyzed by means of indoor simulation seepage experiment results. And then,the factors that influence the technique of percolating water abstraction were studiedand analyzed. Based on the comparement of the indoor text results and those obtainedfrom different theoretical analysis,the water quanity is calculated by the numericalsimulation on the project by Visual Modflow and the analysis of the shape of seepagefield.According to the research, the following conclusions are:(1) The seepage field in the project of Reverse Percolating Water Abstractionfrom Beneath Riverbed is the field with typical thre-dimensionla flow.Closelyhydraulic connection is between river and confined aquifers in the fiter field.(2) The river water is the main supply source to the water quantity of the ReversePercolating Water Abstraction from Beneath Riverbed and the groundwater in sandgravel stratum in the river bed is the secondly one.(3) The quantity of pumping water at the beginning is the groundwater in thesand gravel filters. When the seepage of groundwater forms a great drawdown, Thedrawdown will reach near steady state condition with the recharge of river. And it willextend to the filter bed over time.(4) Due to the river’s seeapgement,There is a low groundwater petrntial zonenear the pipe. The head draw variation range is larger and the hydraulic gradient ishigher at the area near the pipe and vice versa.(5) By using artesian partially penetrating single pumping well method, bigdiameter well method, analogy of filtration ditch, vertical infiltration coefficientmethod and radial well formula substitution method, the water quantity of seepage fieldin the indoor simulation experiment is calculated. Due to different analytical formulaon the hydrogeological parameter selection, the different analytical method ofcalculated value differ from the actual water yield.The calculating difference is largestwith analogy of filtration ditch, the next is with artesian partially penetrating singlepumping well method, big diameter well method and Radial well formula substitutionmethod, the smallest difference is vertical infiltration coefficient method. (6) By introducing numerical simulation method, the water quantity of thereverse infiltration water engineering in Beipiao is calculated, using the VisualModflow software project model. Through the verification of the model space discret,boundary generalized, hydrogeological parameters selection and the model design andits basic model, it is believed that the model of reverse infiltration water engineeringin Beipiao is reliable. On this basis, through to the north in reverse infiltration waterengineering numerical simulation method of calculation, numerical simulation methodin the calculation of infiltration water engineering withdrawal has a wide applicablescope, the reliability of the calculation result is higher.