基于水资源承载力的干旱内陆河流域城市适度规模研究——以石羊河流域凉州区为例

Appropriate urban scale in arid inland river basin based on water resource carrying capacity:A case of Liangzhou District in Shiyang River Basin

以典型的干旱内陆河流域城市武威市凉州区为研究对象,对水资源承载力、城市适度规模的内涵进行阐述;基于可利用水量、水权及水质三要素建立水资源承载能力及城市适度规模计算模型,构建了城市适度规模与实际人口的距离协调度评价模型,并给出评价区间标准;对未来可利用水量、未来可能配水量、未来城市适度规模、水资源超载度进行预测并分析。结果表明:近10 a凉州区的地表径流量变化幅度不大,相比20世纪50年代下降程度显著,凉州区水资源超载度逐年增长,城市适度规模与实际人口的距离协调度处于初级协调发展绿灯区向濒临失调衰退黄灯区过渡阶段。未来20 a水资源超载度增长率降低,基于水资源承载力的城市适度规模远小于预测的城市人口规模,城市适度规模与实际人口距离协调度进入轻度失调双黄灯警区。

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 coo-social development of this region. Taking the Liangzhou District of the Wflwei 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 evi- dently compared with that in the 1950s; the degree of overloading of water carrying capacity in the Liangzhou District had been increasing with annum 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.