Abstract: It is an effective way to increase the carrying capacity of water resources in the arid areas of northwestern China by reforming water resources management policies and adjusting local planting industry structure.Taking-Linze Oasis in the middle reaches of Heihe River as the study area,the inter annual variation of the supply-demand balance about water resources was analyzed using the index of water supply and demand (IWSD) and the index of groundwater exploitation potential (P) based on the data about the utilization of surface water and groundwater,the agricultural irrigation,the distribution patterns of local planting industry and the projects of water conservancy facilities from 2000 to 2015.The maximal carrying capacity of water resources was further studied using the suitable irrigation scale.The results indicated that the balance between supply and demand of water resources was relied on the allocation of water resources in the high water years during the period from 2000 to 2015.The most areas of Linze Oasis showed a moderate supply-demand mismatch or the amount of water supply didn't meet the demands except for Liaoquan and Banqiao in P=50% water warranted efficiency.Shahe and Yanuan were facing the most serious issue of water resource security with the IWSD less than -0.3.There was a significant water supply deficit in Pingchuan and its groundwater exploitation has been continuously surpassing the maximal allowable amount..The balance between water supply and demand in Liyuanhe was squeaked through by increasing groundwater exploitation under the condition ofP=50% water warranted efficiency.The late reforming of water resources management policies and the adjusting of local planting industry as well as the construction of water conservancy facilities has made the water consumption per unit oasis area declined from 1.09 m³·hm^-2 in 2000 to 0.74 m³·hm^-2 in 2015.Although the increase of water resources utilization efficiency can help bear an oasis of larger scale,there is a water deficit of 0.65×10⁸~0.98×10⁸ m³ in order to support the current oasis area.This might be an efficient path to implement a sustainable development as "water-eco-economy" in the oasis area by appropriately reducing the agricultural irrigation area in its marginal transition zones and rationally planning the allocation of water resources in every irrigation area.

Key words: water resources management, planting structure, irrigated agriculture, carrying capacity of water resources, suitable size of oasis