| The groundwater monitoring work in Shandong Province began in the 1950 s,which started relatively early.Up to now,a certain scale monitoring network has been formed,providing a large number of basic data for urban development and construction,rural resource scheduling and development,and related scientific research.However,the monitoring function and accuracy of the existing monitoring network can not meet the increasingly rich production needs,and the existing problems are increasingly prominent: on the one hand,the monitoring accuracy is relatively low;On the other hand,there are redundant monitoring and monitoring gaps in the existing monitoring well network,among which the core problem is the lack of specialized monitoring Wells.The carbonate rocks in the study area are widely distributed and the geological conditions are complex.With the increase of economic construction and population,the exploitation of groundwater increases,and a large range of falling funnel-shaped is formed in some areas,which even causes geological environment problems such as karst collapse,resulting in varying degrees of economic losses.The occurrence of subsidence is largely affected by the dynamic of groundwater level,so it is of great practical significance to establish or perfect the groundwater monitoring system.In this paper,the groundwater level monitoring network in the karst landform distribution area in central and central Shandong is taken as the research object,and a monitoring network scheme suitable for the hydrogeological conditions of the study area is proposed and evaluated by combining groundwater dynamic type mapping method and general Kriging method.The analysis was carried out according to the hydrogeological conditions of the study area and the existing monitoring network.Finally,180 groundwater dynamic types in the study area were determined.Based on the principle of monitoring well layout,the number of monitoring Wells was increased to 190,including 51 original national automatic monitoring Wells,56 original provincial automatic monitoring Wells,8reconstructed artificial monitoring Wells,and 75 new Wells.The standard deviation of Kriging estimation error also decreased from 8.01 to 4.48 before and after optimization,indicating that the error value decreased significantly and the optimization results were reasonable.In order to further improve the response function of the monitoring system to karst collapse,this paper continued to discuss the susceptibility of karst collapse,determined the disaster factors,and established the assessment model of karst collapse susceptibility with analytic hierarchy process,calculated the weight of each factor,and superimposed to generate the collapse susceptibility zoning map.Thus,the well location layout is further supplemented and improved and the well location design priority is evaluated.Finally,on the basis of the optimization scheme,another 15 Wells were added,including 2 reconstructed artificial Wells and 13 newly built Wells.The standard deviation of Kriging’s estimated error was slightly adjusted from 4.48 to 4.46.The optimized monitoring layout fills the monitoring gap in karst areas,realizes the function of responding to the subsidence monitoring,ensures the reasonable exploitation and dispatching of groundwater,and realizes the prediction and monitoring of underground water situation changes in a large range.It will play a positive role in local groundwater management,monitoring and prevention of karst collapse geological disasters.Based on the susceptibility evaluation model,this paper selects an area with high susceptibility to establish a groundwater flow model,and puts forward two mining early warning schemes.Based on the comparison of water balance and objective function of the two schemes,the results show that the above two schemes can control the occurrence and development of karst collapse to a certain extent.However,according to the comparison of factors,the first scheme is better,which is more convenient for the future groundwater dispatching management and the prevention and treatment of geological problems. |
