Abstract:

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