Abstract: With a hydropower project as an engineering example, we researched the effect of weir type and big submergence depth on the discharge capacity of low weir. Results showed that as for low weir with big submergence flow, the ratio of weir thickness to waterhead δ/H≤0.67, and the discharge capacity of broken-line practical weir with steep downstream weir slope is larger than that of WES weir. For low weir with big submergence depth, the discharge capacity can be increased by declining the crest height, but with the rise of submergence depth, the influence of weir height and weir type on the discharge capacity is weakened.

Key words: low waterhead, big submergence, overflow weir, discharge capacity