Three Dimensional Hydrogeological Structure Modeling And Its Numerical Simulation In Tianshan North Foot

Tianshan north foot is located in the western arid land of China and belongs to typical continental arid climate.The water resources distribute non-uniformly.The unreasonable development and irrigation from water diversion in these years have caused a series of eco-environmental problems.Therefore,it is very important to investigate the hydrogeological structure in Tianshan North foot and to exactly evaluate the regional groundwater resources,to design and set the feasible groundwater development plan and to achieve the goal of improving eco-environment.This thesis is based on the "Special research on Groundwater resources and its environment in Zhunger Pedi(Basin) in Xinjiang Autonomous Region "(Project No. 200310400012) from China Geological Survey.The study results in the thesis are as follows.1.Basically Investigating the quaternary geology and the spatial distribution and structure characteristics of groundwater system.The method of virtualizing boreholes is used to increase borehole data in accordance with the well-developed geological structures,the complex strata and lithology,the multiple geomorphologic units,the large area and the unevenly distributed boreholes.The strata structure is generalized by combine the similar water-beadng formations and ignoring formation lenses.Based on the platform of geostatistics and Groundwater Modeling System(GMS),the three-dimensional geological structure model has been set up which reflects the hydrogeological conditions in the study area and the visualization of hydrogeological structure has been realized.All of these provide the foundation for setting up hydrgeological concepts.2.Time-scale treatment has been carried out for source and sink terms on the basis of hydrogeological conditions,precipitation-surface-water-groundwater transformation law and the analytical results of groundwater regime genetic types.The temporal distribution of river water seepage into groundwater system is calibrated on the basis of the river seepage simulating test in typical sites and river seepage mechanism study.The hydrogeological conceptual model and groundwater flow numerical model in the study area are set up.The Module MODFLOW in GMS software is used to solve the model.The gradient field, lowering velocity field and water balance analysis are used to calibrate and verify the model. By optimizing the hydrogeological parameters and sub-region makes the numerical model have high simulation and reliability.3.According to groundwater sustainable development,the ecological water table depths 3-5 meters on the geo-eco- environmental indexes designed by the study group are regarded as constraint conditions.Six sub-plans under two plans are designed for simulating groundwater dynamical field and for evaluating groundwater resources.The optimal groundwater development plan under "500 Project" are got.The exploitable groundwater resources in the year 2010 is 19.25×108 m3/a,and that in the year 2020 is 20.34×108 m3/a, the ineffective evaporation which will be trapped is 1.98×108 m3/a and the groundwater system is basically in balance state.The above-mentioned research results have theoretical and practical meanings in exactly evaluating groundwater resources,protecting surface eco-environment and rationally developing and utilizing groundwater.The main part of the thesis has been adopted in the project total report which has been approved by the experts in the project examination and assessment.