Risk control of groundwater exploitation for Zhangye basin in the middle reaches of Heihe River basin, China

Regulation of the water table is a feasible and effective way to reduce the risk of groundwater exploitation. An index system of groundwater exploitation risk evaluation is developed. The groundwater numerical simulation model is established for Zhangye basin in the middle reaches of Heihe River basin, China. Based on the identification and validation, the model is used for numerical simulation and forecast of groundwater exploitation under the conditions of current and planned development. The results show that the increase of groundwater exploitation amount causes the falling of water table. The increase of groundwater exploitation is 7600 × 104 m3, which can displace the surface water amount of 10 100 × 104 m3. The annual river runoff can increase 7536 × 104 m3. It is beneficial to the let-down flow from Zhengyi Gorge cross-section, and also provides the basis for decision on risk control of groundwater exploitation.

Numerical Simulation and Prediction of High Fluorine Groundwater Transport in Zhangye Basin

Simulate Feflow with finite element method, and establish flow model and solute transport model of high fluorine groundwater area in Zhangye Basin. Predicting groundwater system response under different exploitation scheme, and evaluating the risk of deep low fluorine groundwater polluted by shallow high fluorine groundwater. The results showed that, firstly, the existing exploitation intensity and the increasing exploitation intensity of the local planning would lead to groundwater table descent, for the deep groundwater head is higher than phreatic water in above scheme, the polluted risk of low fluorine freshwater is low. Secondly, low and deep groundwater “cross strata” caused by well completion technology would lead to deep low fluorine freshwater polluted, and the high fluorine polluted area caused by single well is limited, but the polluted risk of low fluorine aquifer is increasing with that confined water head is lower than phreatic water in local concentrated excess exploitation area. Propose the measures and suggestions of the groundwater sustainable utilization.