Abstract

Hydraulic characteristics in fluctuating backwater area of Mid-minitype plants are affected by runoff and operating modes of the reservoir. Given by the same operating level, the slope increases with larger discharge in the reach; while decreases with larger operating lever on condition of the same discharge. After the mid-minitype plants are finished, affecting factors of fluvial process of fluctuating backwater area in alluvial mountain rivers are relatively rich, including the bed material, operating modes of the plants, and the incoming water and sediment from the upper reach. Generally, the shoals occur erosion while the deeps occur siltation during flood period, and there appears back-silting during post-freshet period.

In fluctuating backwater area, the sediment discharge intensity is mainly affected by the velocity in the channel, and the sediment discharge is affected by erosion duration. When regulation work of shoals in fluctuating backwater area is carried, the design stage can be progressively increased to prolong the erosion duration, and the regulation width be progressively reduced to improve the streamwise velocity in the channel, thus the sediment discharge during mid-low water period could be enhanced.

Keyword: alluvial mountain rivers; fluctuating backwater area; evolution; regulation principles