Exploration And Evaluating To The Kast Groundwater Resource In North Of Jining Shandong Province

Jining city is the economic and cultural center in southwest of Shandong province. Seventy percent of the land is irrigable land, and most of which depends on the irrigation from groundwater. With the development of economy and the acceralation of urbanization, the industrial organizations' demand of water is increasing with time , at the same time ,the quality of the surface water worries people more and more .Therefore, groundwater becomes the main water supply. Excessive exploited groundwater in long term may make the level of the groundwater fall continually, groundwater resource dry up, and generates more environmental geologic problem, such as land subsidence and crast collapse and so on, So relative exact assessment of the groundwater resource in order to use and exploit groundwater rationally is very necessary.Combining with the water resource planning by the local concerning department, we made a reconnaissance and evaluation of the karst water contained in the concealed carbonate rock crack lying in the north of the Jining city. Because the seating of the crack aquifer was very big and the research work in the past was few, therefore on the basis of using engineering physical detection, hydrographic geologic survey ,dynamic observation, the reconnaissance employed uranium isotopic tracing method and group well pumping test to find out the recharge resource and runoff path etc of the crack karst water. A groundwater numerical simulation software named VISUAL MODFLOW was used to establish a three-dimensional groundwater numerical model, and to identify the hydrographic geologic condition of the studied area.Hydrologic budget method was firstly used to estimate the permitted exploitation of the karst water resource, and then was the verified numerical model to forecast the maximum exploitation on some fixed confining conditions. The two estimated permitted exploitations by this two methods was 19.20×10~4m~3/d .and 18.46×10~4m~3/d. respectively ,which is very near to each other,, therefore the two estimations can verify each other and promoted the reliability. The mean value of 18.83×10~4m~3/d is adopted in this study.The model forecasted that the maximum additional drawdown caused by exploiting of the karst water was lower than 2 meters, having little effect on the agricultural use. Extensive exploiting of the karst water may induce the krast rock collapsing of the mountain's edge in the south of the Jiaxiang town,but the harm was small; It wouldn't induce land subsidence, and had little effect on the groundwater quality.