Abstract: The Shiyang River is a typical basin which is lack of water in northwest arid zone with relative backward social economy and ecological environment security problems in its urbanization development. Besides, oasis is a compound ecosystem which is affected by natural and human factors of arid land. The oasis cities relying on inland river basin are the cluster centers of human production and life where also have the most vulnerable human-environment relationship. Water and soil resources make the most important role of regional society、economy and environment harmonize development and they always interact and restrict each other. To explore the water-soil utilization ecological risk aims to reveal its time-space changes and effect, by taking measures we can allocate resource more rationally in oasis region and make harmonize development between social economy and environment protection. The article takes Wuwei city as the case, based on land use change data in 1987 and 2010,bulletin of water resource from 2003 to 2009 then chooses evaluation index within the composite system of “water-soil resource–ecology –society–economy”, then it constructs the water-soil utilization ecological risk assessment model and analyzes its dynamic and spatial change. The assessment model of land resource integrates coverage landscape index as well as land use index; with the thought of regional shortage risk, the water ecological risk model makes comprehensive evaluation from supply、utilization、maintenance and exploitation. At last, countermeasures referred to risk are put forward in this paper. The conclusions show that the land use composite risk index was increased from 1987 to 2010, land use pattern changes produced ecological risk to some degree; from 2003 to 2009, the level of water ecological risk was raised up significantly, counties should take appropriate measures to control the risk change; the water-soil ecological risk exists spatial otherness within the region: ecological risk of middle and lower area of the Shiyang River basin is higher than that of upstream areas. The water-soil utilization ecological risk evolution process of Wuwei is so complex with all kinds of interactive factors. In order to promote the rational development in oasis city of overall benign, we must overcome resource deficiency, develop water-soil resource rationally and promote environment improvement and recovery by scientific means.

Key words: Shiyang River, oasis city, soil and water utilization, ecological risk, Wuwei City