The Study On Groundwater Dynamic Variation Characteristics And Water Resources Development And Utilization Plan In Minqin Basin

Minqin Basin is located in the lower reaches of Shiyang River Basin and extends between Badain Jaran Desert and Tengger Desert.It is of great significance to prevent the two deserts from closing together and has a barrier effect on Hexi Corridor.In recent decades,the groundwater resources in Minqin Basin have decreased sharply,and the water level has continued to fall,causing serious ecological problems such as vegetation deadness and desert invasion,threatening the survival and development of local residents.This paper divides the groundwater dynamics in Minqin area into exploitation type,irrigation infiltration-exploitation type,river infiltration-exploitation type and run-off type.Describing the characteristics of changes in water level and water volume for many years.From 1985 to 2016,the groundwater level in Minqin Basin declined overall,with the most obvious decline in the irrigation area,with a cumulative water loss of 64.01×10~8m3over many years.After the comprehensive management of Shiyang River Basin in 2007,the rate of water level decline slowed,and a positive balance began to appear in 2015.Through correlation analysis,it is proved that human exploitation and surface water irrigation are the main factors affecting groundwater resources.A conceptual model of hydrogeology and a numerical model of groundwater flow in Minqin Basin are established.From 2002 to 2018,the average annual replenishment volume in the basin is 1.36×10~8m3/a,and the average annual discharge volume is 2.30×10~8m3/a,showing a negative balance overall.The exploitable ground water resources in Minqin Basin is calculated to be 1.30×10~8m3/a.The exploitation quantity,water balance,water level change rate and resource water level early warning indicators of Minqin Basin are set.Predicting the amount of surface water coming in three situations:abundant,flat and dry(incoming water frequency p=25%,50%,75%).At the same time,different groundwater extraction schemes are drawn up and substituted into groundwater flow prediction models(prediction period 2019~2040).Analyzing the running results of the model and eliminate the early warning plan.In order to ensure the rationality of the rationality of the plan,the water demand in the study area is predicted and the supply and demand analysis is conducted.Finally,determining the annual groundwater extraction in the abundant,flat and dry water years are 0.91×10~8m3/a,1.04×10~8m3/a and 1.17×10~8m3/a.The discharge volume of Qingtu Lake is 0.3×10~8m3/a,0.15×10~8m3/a and 0m3/a.After the application of the plan,the groundwater level will continue to rise during the prediction period,the groundwater resources can be replenished and the water surface area of Qingtu Lake will be maintained and expanded.Finally,refining the total exploitation amount and the annual water level change of the monitor wells to obtain the dual-control management index of groundwater volume and level in each township.Combining with the current situation of local water resources management,suggestions are made for the management of groundwater in Minqin Basin.