| The paper sets up a groundwater three-dimensional flow model to predict the karst groundwater regime in East Area of Wei Bei in Shanxi Province on the condition of exploitation. A model must accord with the actual condition of research area, or it will lose in reality. The paper will stress the essential condition of research area during the process of building model.The former is of opinion that the boundary of Karst-groundwater system in research area is in consonance with the boundary of "Tong-Pu-He Subsystem of Karst Groundwater" in East Wei Bei. In research area, the Tertiary system (N) is water-resisting layer. From the mountain region of Western and center, one part of the rainfall infiltration directly flow towards the east, the others flow towards the deep south, passing through the sunken block and diverting to east also. The groundwater, flowing towards east, outflow a part in Yuan Jiapo and WenTang spring aside Luo river, and the rest majority completely drain in the bottom glade of Yellow River and its nearby springs-MaFen and Chunv spring.On the basis of previous research view to the boundary of Karst-groundwater system in research area, Chapter Two starts with the natural geography condition of research area and analyzes the condition of geology and hydrogeology carefully. Accordingly, several queries are brought out as follow: Is the Tertiary system (N) confining layer? Do whole of the groundwater flow from the western recharge area to eastern? Do springs and Yellow river be the only sink of the karst-groundwater? Could there exist another possibility for the south boundary of the system as follow: The rainfall infiltrates in the outcrop carbonate-mountain area of Western, and moves towards south and deeper along carbonate rocks, then moves upper through the overlain Tertiary system (N) with a thickness of 400m (instead of running off to the springs and Yellow river through a long approach of least hydraulic gradient), and then mainly transforms into the horizontal drainage in the loess layer of Quaternary, finally drains in Lu-Botan depression. Thus we can explain why the groundwater with high mineralization degree in Lu-Botan depression-gesso in terrane of the Tertiary system is leaching by groundwater.On the basis of the analysis above, the paper points out that the main aquifer system are composed of Cambrian and Ordovician. Intensive faults segment the aquifer system to be a complicated mulit-layer system. Then, with correlative information and considering the needs for building model, strata are thus divided into sub-layers in the model: the high permeable aquifer is Oif2-4. O2m and C2, among them, the permeability of the O2m is the best, O2f2-4 better, and C2 inferior; O2f1, O1, C3, C1 are the worse permeable aquifers of different degrees, the Tertiary system (N) is the worst permeable aquifer. On the basis of analysis for recharge , flow-off and drainage of research area, the paper concludes that the main possible cause for the fall of water head is groundwater exploitation by comparing the curve of rainfall-time and the curve of observation heads of some observation well.In the third chapter, the paper describes the conceptual model of research area: in plane, therange and boundary of the model accords with that of Tong-Pu-He Karst-groundwater sub-system; in vertical, the model ranges from the bottom of Cambrian to the phreatic surface. The upper boundary of model is the phreatic surface having rainfall, river and reservoir recharge and spring drainage. The upper of the east model boundary remains constant head and the at the lower of it, there might exists a diffluent interface. So the east and west sides of the diffluent interface are respectively the drainage area of east and west karst-groundwater of Yellow river. The diffluent interface can be regarded as the Zero-flow boundary. Although regarded as zero flow boundary in initial, the feature of the south, west and north boundaries should be determine by model calibration. The source and sink is mainly pumping well.
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