岷江上游水电开发特点及其空间格局分析

研究流域的水电开发类型与空间格局,可为水库群的累积环境影响评价、流域水电优化布局等提供科学参考。在流域分割的基础上,对岷江上游水电站的基本类型、水电站的空间分布格局进行了全面分析,并构建水电开发率、水电开发密度和水电开发强度3个指标对流域水电开发程度作出综合评价。结果表明岷江上游流域水电站类型以高水头低闸坝的引水式小水电为主,高坝大库相对较少。梯级水电开发已拓展至岷江三级支流,汶川—都江堰河段是干流水电开发程度最高的河段,杂谷脑河是水电开发程度最高的一级支流流域。岷江上游流域的水电开发率远高于全国平均水平,梯级水电开发密度大于国内主要河流。农村小水电占水电站总数的82%,梯级农村小水电对生态环境的累积影响是将来值得深入探讨的问题。

CHARACTERISTICS AND SPATIAL PATTERNS OF HYDROPOWER DEVELOPMENT IN THE UPPER MINJIANG RIVER BASIN

Studying hydropower development types and spatial patterns is useful to analyze the cumulative effects of reservoirs and optimal layout of hydropower in watersheds. Despite a few literatures has discussed the assessment method of hydropower development level, the evaluation method is still given priority to a single index on hydropower development rate. However, the single index cannot truthfully reflect the spatial distribution of hydropower station in a whole watershed, and is hard to reflect the differences of hydropower development in different river sections. These shortcomings are not conductive to the study of cumulative effects that may be caused by cascade hydropower stations. Based on the separation of the whole basin, we analyzed the types and the spatial patterns of hydropower located in the upper Minjiang River Basin. Then, we built three indices, namely, hydropower development rate, hydropower development density and hydropower development intensity, to comprehensively assess the hydropower development degree of study area. Finally, we compared these indices across many river basins in China. The results were as follows. (1) The main type of hydropower plant in study area is not large hydropower but small diversion hydropower with high water head and low dam. (2) Cascade hydropower development has been expanded to the third level tributaries. The pattern of intensive cascade hydropower development may give rise to the disappearance of some aquatic organisms in “dewatered” river sections, thus may result in the gradual evolution of aquatic ecosystems into seasonal terrestrial ecosystems. It may also speed up the flood collection rate, an affect the safety of flood controlling. (3) The hydropower development rate, hydropower development density and hydropower development intensity of Zagunao River, a main tributary of the study area, were as high as 99%, 057 and 017, respectively, making it the highest developed tributary. Wenchuan Dujiangyan section is the highest developed section of main stream. (4) Compared with the average level of hydropower development rate in China, the intensity of cascade hydropower development is much greater than that of other main rivers in China. (5) As the main hydropower type of study area, the biophysical cumulative effects caused by small hydropower deserve further study