Abstract: Located in the Sangong River watershed in the southern marginal zone of Junggar Basin in the northern piedmont of the Tianshan Mountains, the study area is an irrigated area dominated by agriculture. There are 3 small streams with an annual runoff volume of 9. 2222×107 m³ in the watershed. The exploitation and utilization level of the water resources in the watershed is rather high. When the exploitation and utilization of the surface water reached a saturation point, the exploitation of the groundwater began to be sharply increased, especially from the perimontane groundwater reservoir. In Fukang County of Xinjiang, the perimontane groundwater reservoir with an area about 140 km² and the fine storage conditions forms in the loose sand-pebble-gravel stratum composed of the connecting alluvia-l diluvial fans after the 3 small streams flow out of the debouchures, a great space of groundwater storage is provided, and the groundwater reservoir is steadily fed by permeation of the streams and rainfall. At present the annual exploited groundwater volume is 4.2273×107 m³ and is increased in an annual speed of 4.41×105 m³, whereas the groundwater level is lowered in an annual speed of 0.4 m, the drawdown funne-l like areas appear in some regions, and some environmental problems occur. By using the data of the dynamical monitoring and the exploited volume of groundwater and the runoff volume in the watershed as well as the correlative analysis, in this paper the causes resulting in the drawdown of the groundwater level is analyzed, the models for determining the rationally exploited volume of groundwater are developed and verified by water budget method, and the exploitable volumes of groundwater under the different runoff conditions in the Sangong River watershed are calculated, which reveal that the present demand of water volume does not accord with the total volume of water resources in the watershed. By predicting the demanded water volume in the irrigated area, some suggestions are put forward for alleviating the contradiction between the water consumption and the water resources in the watershed and for rationally utilizing the groundwater of the perimontane groundwater reservoir.

Key words: groundwater reservoir, groundwater, water resources, Sangong River watershed, Xinjiang