Study On Numerical Model Of Groundwater Flowin Hetao Basinand Salinization Water Table Control

Hetao plain includes two major areas: Houtao basin and Hubao basin. Hubao basin includes the important cities of Inner Mongolia, Hohhot and baotou, Houtao plain is the base of grain, industry and dairy of the country and the autonomous region. The rapid development of economic cause the increasingly serious shortage of water in the region.At the same time, unreasonable use of groundwater causes the environmental geological problems, such as salinization problem in Houtao plain, which influence and restricts the development of the region’s economy.Therefore, it`s necessary to do further research onhydrogeological conditions of Hetao basin and evaluate the groundwater resources, then do research on thesoil salinization in Houtao plain to solve the problem.This paper use GMS and Modfow software establish 3-D twolayer groundwater flow numerical simulation model of hetao basin on the analysis of hydrogeological condition in the study area. According to the data of the project, the simulation period of present model is determined to be 2005-2010 and the forecast model 2010-2030. Through model identification, the paper finally establish a model that can reflect the characteristics of the actual aquifer, then evaluate groundwater resources and do research in salinization water level control.According to the model, The groundwater recharge resources of the present status in the Hetao basin is 45.94′108m3/a, the discharge resources is 48.00′108m3/a and the differences is-2.05′108m3/a. Basing on this, the paper evaluate the groundwater recharge resource, the result shows that the recharge resource of Hetao basin is 42.20×108m3/a. The Yellow River irrigation is the main source of recharge, is25.63×108m3/a, which is about 60.73% of total recharge; then recharge infiltration is also an important source. For the confined aquifer, the recharge resource is 3.85×108 m3/a, including leakage recharge and lateral inflows, separatelyis about68.21% and 32.79% of total recharge.Through the study of soil salinization water level threshold, the paper determinethesand threshold of the groundwater depth is 2.6 m, fine sand is 2.3 m, and the sub-clay is 2.1 m.Other area meet the constraint conditions that soil desertification, the threshold of soil desertification is 5m.Take the status of underground water level into consideration, the paper calculate the groundwater between the range of the ecological regulation, then according to the Yellow River planning scheme determine the water resources development and utilization scheme.After analyzing the change of balance according to the predicted model, the water level significantly reduced after water planning, average water depth decrease from 2.33 m to 4.01 m. The total recharge reduce 10.69′108m3/a, reduction is mainly evaporation which reduce from 59.9% to 26.6% of the total discharge. The decrease of evaporation reduces the water loss and the decline of water level ease the salinization problems.