Abstract: Most of the cities in the arid inland river basin of northwest China are being perplexed by the problems of water shortage and inefficient water utilization. Thus the process of urbanization and the city development scale in this region have been restricted by the water shortage and irrational water utilization structure. It is significant and in urgent need to research the urban appropriate scale based upon its water resource carrying capacity as water shortage and fragile ecological environment has been the key factor which restricts the ecosocial development of this region. Taking the Liangzhou District of the Wuwei city located in the Shiyang River basin as the case study, based on available water quantity, water rights and water quality, computing models for urban water resource carrying capacity and for the urban appropriate population scale were established. Then, a model named after the coordination degree evaluation was set up for researching on the relationship between urban appropriate population scale and its actual population, followed by a detailed prediction and analysis on the available water quantity, water allocation, the degree of overloading of water carrying capacity and urban appropriate scale in the future. The results show as follows: the surface runoff in the Liangzhou District changed slightly from 2001 to 2009, however, it dropped evidently compared with that in the 1950s; the degree of overloading of water carrying capacity in the Liangzhou District had been increasing with annual average growth at 4.76% from 2000 to 2009, and the urbanization level was with annual growth of 3.86% at the same time, while the urban appropriate scale had been with negative growth, and this could also be reflected by the index of distance coordination degree between appropriate population and actual one, which was in the transition from Green Zone(namely slight coordination) to Yellow Zone(namely being on the verge of disorder); in the next twenty years, the average annual growth rate of urbanization would be faster(at 5.16%), while the growth of the degree of overloading of water carrying capacity would slow down with the average annual growth rate at 2.48%, but the urban appropriate population scale based upon water carrying capacity would also be smaller than the predicted urban population, thus the index of the distance coordination degree would belong to the Double-Yellow Zone (namely being slight incoordination). These results indicate that, as for the urban areas in the arid inland river basin of northwest China, reasonable urban development model should be adopted rather than extend the urban city scale with little consideration on the water carrying capacity.

Key words: water resource carrying capacity, appropriate urban scale, coordination degree analysis, Shiyang River Basin