Runoffs of the Xiangride and Qaidum Rivers in the Arid Qaidum Basin, Northwest China

Runoffs collected by the rivers provide water needed to sustain unique ecosystem in an arid basin. Diversion for agricultural application could cause damages to the vulnerable ecosystem. The authors assessed runoffs in the mountainous area, interaction of river water and groundwater, and consumptive uses of water in different geographic units such as desert, manmade oasis, marsh land and terminal lakes in the arid Qaidum Basin in North Qinghai-Tibet Plateau. The Xiangride River collects approximately 510 million m³ runoffs annually, of which 140 million m³ is diverted for agricultural irrigation. It then recharges underlying aquifer and provides water for vegetation along the river. The water eventually disappears from the riverbed and reappears as springs, forming the Qaidum River at approximately 20 km downstream. It collects about 90% of seepage water. It is concluded that irrigation diversion has caused groundwater level decline and shift of the spring belt downstream, resulting impacts on ecosystem.