Study On Groundwater Dynamic Change And Water Balance In Shijiazhuang Plain

Groundwater is an important part of water resources,which is widely used in every link of production and life.As a resource-based water shortage city,Shijiazhuang city has scarce surface water resources,and its economic development relies on over-exploitation of groundwater all the year round,which leads to the continuous expansion of the area and depth of groundwater falling funnel,and the contradiction between supply and demand of water resources is very sharp.Therefore,it is very necessary to grasp the characteristics of spatial-temporal dynamic changes of groundwater in Shijiazhuang,find out the amount of groundwater resources,and comprehensively and systematically understand the hydrological cycle process of Shijiazhuang city.Firstly,the study is carried out based on the groundwater depth data from automatic monitoring stations in the Shijiazhuang plain from 2018 to 2020.Six representative observation wells are selected to analyze the temporal dynamics of groundwater depth.Kriging is used to interpolate groundwater depth data,and thereafter contour maps of the spatial distribution groundwater depth are drawn,where its spatial variation is analyzed.The groundwater storage change in each county are calculated by Zonal statistics.The results show that the groundwater level in the urban municipal district and the Gaocheng district rise significantly,while the groundwater level in other areas still has declining trend.However,the decline rate is less intensive compared with that before the pimping reduction.The overall groundwater storage change in the Shijiazhuang plain is still decreasing.Secondly,a distributed hydrological model—MIKE SHE model is used to simulate the hydrological cycle in Shijiazhuang plain.In this thesis,five modules,including evapotranspiration,overland flow,unsaturated zone flow,saturated zone flow and rivers and lakes,are constructed.The groundwater head time series data from 80 automatic monitoring stations in the study area are used to calibrate the model.One observation station is randomly selected from each district and county in the plain area,and a total of14 observation stations are used to verify the model.The results show that the correlation coefficient between simulated values and measured values of 10 of the 14 observation stations used for validation is above 0.8,the Nash coefficient is above 0.63,and the root mean square error range from 0.62 to 4.45,which is relatively small compared to the whole study area.The MIKE SHE model constructed in this thesis can describe the temporal dynamics of groundwater head in Shijiazhuang plain,which can provide a research basis for the fine management,development,utilization and protection of groundwater resources,and promote the sustainable development of water resources in this region.