The Application Of Numerical Simulation In The Valley Area

Proper evaluation of groundwater resource is the precondition and basic of effective exploitation and scientific management to groundwater resource. Take Xiajiawanzi well field in Beipiao City, Liao Ning Province for example, according to observed precipitation, evaporation and groundwater level etc., based on hydro geological condition of the study area, the hydro geological conceptual model and relevant groundwater flow numerical model was established, and Visual MODFLOW was used to simulate groundwater flow. Change of groundwater level and extension of groundwater cone of depression were predicted under both current and increased pumping scheme of this well field.After calibration and verification of the numerical model, sensitive analysis was made for the selected five parameters, including specific yield of aquifer (Sy). conductivity (K), conductivity of riverbed sediment materials, precipitation infiltration coefficient and hydraulic conductance (C) of general head boundary (GHB). The result shows that the model is relatively sensitive to Sy and hydraulic conductance of GHB, and the groundwater availability of study area is 2.2×10~4m~3/d, which provide foundation of groundwater level prediction. According to water balance analysis of whole study area under current condition, groundwater is over-exploited during simulation period, and calculated with spatial analyses function of Surfer, area where groundwater level below criteria due to groundwater over-exploitation is 3.3km~2, which takes up 46.4% of the whole area. By modifying scheme of wells distribution, such prediction was made that under the increased pumping rate condition, the maximum pumping rate is 3.5×10~4m~3/d, 3.2×10~4m~3/d , 3.0×10~4m~3/d under relevant frequency of 25%, 50%, 75%, which provide scientific basic for operation and management of the well field.