干旱区生态环境知识资源中心

Groundwater resources in arid areas are of great significance for domestic and drinking water uses, industrial and agricultural water supplies, and ecosystem maintenance. Excessive groundwater exploitation would inevitably lead to water table drawdown and ecosystem degradation. The Qaidam Basin is an inland arid area located in NW China. The piedmont is a large thick sandy gravel porous phreatic zone with rich groundwater resources, which primarily recharges by vertical infiltration of rivers from mountains. Four wellfields with a total exploitation amount of 160,000 m(3)/d were proposed in the Qaidam Basin. However, water table decline occurs in most downstream spring-derived rivers and associated wetland areas. The range of 0 to 1 m drawdown is 1232 km(2) and that of >1 m drawdown is 703 km(2), accounting for 50% and 29% of the total area of spring-derived rivers and associated wetlands, respectively. The planned exploitation amount is clearly too large to result in groundwater withdrawal and ecosystem degradation in the downstream. This study considered ecosystem protection constraints (i.e., no water table drawdown in spring-derived rivers and associated wetlands). Based on groundwater numerical simulation results, the total allowable exploitation amount is estimated to be 50,000 m3/d, i.e., 30% of previous estimates. This study provides a reference for ecological protection during groundwater development and utilization planning in similar arid areas. The results have notable implications for maintaining the health and development of ecosystems and optimizing utilization of groundwater resources in arid areas.