Study On Double Control Index Of Shallow Groundwater Quantity And Water Level In Shijiazhuang Plain Area

Unreasonable exploitation and over-exploitation of groundwater resources in over-exploited areas in China have caused a series of water resources and ecological environment problems,which have attracted great attention from the CPC Central Committee and the State Council.With the development of groundwater management and protection system,the dual control management of groundwater quantity and water level began to be written into various management systems.Under this background,it is very necessary and urgent to work out a set of double control index determination system of groundwater quantity and water level suitable for over-exploitation area.In this study,the concept of double control management of groundwater quantity and water level and the concept of controlled management of groundwater level are introduced.On this basis,the internal relationship between groundwater quantity and water level is discussed,and the quantitative research methods of groundwater quantity and water level,such as water balance method and numerical simulation method,are compared and analyzed,which provides theoretical basis for the determination of double control index.Guided by the problem of groundwater double control management,this study puts forward a set of reasonable technical system for determining shallow groundwater double control index.Division of groundwater management division is a prerequisite for implementing dual control management.This paper summarizes the division principles of groundwater management division.A certain number of control monitoring wells,mainly including funnel area water level control wells,regional water level control wells,etc.,need to be set up in the management division.For the convenience of assessment,representative monitoring wells which can represent the overall water level change in the region are selected by Tai Sen polygon method.At the same time,different schemes for determining groundwater double control index are put forward.Finally,the annual assessment method of groundwater level is introduced,which is mainly to set a certain degree of relaxation in the assessment of dry years.In this study,the method and scheme for determining the double control index of groundwater quantity and water level were applied to Shijiazhuang plain area for example verification.According to the principle,the study area is divided into 13 groundwater management areas,and 12 representative regional control monitoring wells and 1 funnel area water level control well are determined.The quantitative relationship between shallow groundwater level and water quantity in the study area is established by water balance method.Combined with the actual exploitation and management objectives of groundwater,three schemes for determining double control indexes are given:(1)the scheme that the groundwater level will not decrease in the future and the water quantity will not exceed the exploitable amount of groundwater;(2)The plan of restoring the water level in 2030 to that in 2010;(3)There is a plan for mining quantity planning in 2019-2022.The water balance equation is used to calculate the double control index of water quantity and water level in each district under the three schemes.Taking the first scheme as an example,the groundwater level index of Xinle City in the future is 45.41 m and the mining yield index is 121.25×106m3.At last,referring to the annual assessment method of groundwater level,the annual assessment water level relaxation amount of each sub-region in dry year is calculated,and the relaxation amount ranges from 0.31m-1.16 m,among which the maximum value in Shenze is 1.16 m,and the minimum value in Wuji is 0.31 m.The relaxation amount is closely related to local hydrogeological conditions and groundwater exploitation.