The Research On The Occurrence Regularity Of Fissure-karst Groundwater In Wangcheng Area,Laixi City,Shandong Province

Be affected with the lack of surface water and the pollution of Quaternary groundwater,the problem of water supply abnormally in the city of Laixi,Shandong province becomes increasingly prominent.It is seriously affecting the normal operation of the city water supply and agricultural water supply,by the way,it is seriously restricting the economic development and the normal life of the Citizens.Fortunately,there is abundant fissure-karst groundwater in the deep layer of marble,and the quality of this water is very good,which is less affected by human activities.In this article,the author takes advantage of the hydrogeological survey data combining with the means of ground survey,geophysical exploration,geology drilling,and experiment to research the occurrence law of fissure-karst groundwater in this area.By using the value of RQD,a new calculation method and classification standard of rock fissure development degree are summarized,and the law of fracture development degree in the research area is analyzed.Build the conceptual model in this area where is filled with fissure-karst underground water,Analysisthe fissure-karst groundwater hose into control factors,researches the variation law of fissure-karst groundwater with formation,lithology,structure and other factors,analysis the features of recharge,runoff and excretion characteristics of fissure-karst groundwater,besides,the occurrence law of fissure-karst groundwater in three typical areas has been researched specially.The fissure-karst groundwater resources is calculated and the water quality is evaluated.Based on the above mentioned hydrogeological model,build a groundwater flow numerical model of fissure-karst groundwater in the city of Laixi using the software of Visual Modflow4.6invented by Waterloo company in Canada.Through the model,predict the groundwater dynamics,and determine the fissure-karst groundwater area where is suitable to exploit,in order to provide support for the exploitation of fissure-karst groundwater reasonably.The main conclusions are as follows:(1)The law of fracture development in the research area is greatly influenced by the fracture structure.(2)The occurrence of fractured fissure-karst groundwater in the research area is mainly controlled by the factors of structural and stratigraphic.(3)There are two characteristics of recharge,runoff and discharge of fissure-karst groundwater in Wangcheng area of Laixi.(4)There are three favorable areas for exploitation of fissure-karst groundwater in the research area.(5)The quality of fissure-karst groundwater in the research area is good,which conforms to the grade III standard of groundwater quality and the hygienic standard of drinking water.(6)Through the numerical simulation of groundwater flow in the research area,the author predicted and calculated the maximum allowable exploitation value is about 55thousand m~3/d,and the fitting result of the model shows that the model is consistent with the actual situation.