Evolution characteristics of groundwater flow systems in the past 50 years in Kongqi River irrigation district, Xinjiang, China

Abstract

The Kongqi River Irrigation District (KRID) in Xinjiang, China, has a serious problem of groundwater overexploitation.A scientific understanding of the development conditions and evolution characteristics of regional groundwater flow systems is the basis for optimizing the utilization of groundwater resources.The variation characteristics of groundwater flow systems in KRID, from 1970 to 2020, were simulated and identified via numerical modeling and streamlines tracing of the three-dimensional steady-state groundwater flow in the Quaternary aquifers.As indicated, a complex patterns of groundwater flow systems can be developed around the Kongqi River, with streamlines linking different recharge and discharge zones, varying with the pumping intensity of groundwater in KRID.In the 1970s when the condition was close to a natural state, groundwater flow systems with north-to-south flow dominated the irrigation district, and the spatial pattern depended on hydrogeological parameters and recharge-discharge factors.There were possibly 1-4 flow systems discharge to the Kongqi River in the natural condition.Currently, groundwater is strongly exploited in the irrigation district, and groundwater flow systems are attracted by the groundwater withdrawal funnel with recharge from surrounding areas, cutting off the groundwater flow system with recharge from the leaking upper reaches of the Kongqi River and discharge into the middle-lower reaches.In the past 50 years, the projected area for groundwater flow systems of the phreatic evaporation discharge has decreased by 29%, while the projected area for groundwater flow systems of pumping discharge has increased from zero to 40% of the total model area.Phreatic evaporation plays an important role in supporting natural ecosystems.Therefore, groundwater exploitation should be controlled in the irrigation district, to maintain the development condition for groundwater flow systems of phreatic evaporation discharge.

Keywords

• hydrogeology
• groundwater exploitation
• phreatic evaporation
• groundwater flow modeling