| Summary: | 碩士 === 國立中興大學 === 水土保持學系 === 88 === In this research , three discharges and one experimental sand for three slopes and four sand dunes placement for experimental equipment to investigate the relationships among depth , velocity , specific energy , and Manning’s roughness n . Besides , sediment-loaded experiments also were conducted to examine the deposit condition at the downstream of no opening sand dunes in the fishway .
Besides , for the sake of to save the problems of the depth which is internal fishway in the low water period , there fore the study not only to the experiment of sand dunes without opening but also to proceed a test of sand dunes with opening , in order to understand these types of sand dunes , whether or not enhance the death of each section for fishes to swim .
By way of to analyze the data of the test we can understand no matter sand dunes to have or without opening , when the interval of sand dunes are more small not only the depths are deeper but also Manning’s roughness n to become large to form velocity slow down , at most can decreases 53.6 percent , but enhance the depth of sand dunes with opening have not ideal expectable , only the depth on an inclined plane of sand dunes have obvious to deepen , but to stabilize flow and to eliminate silt are better than sand dunes without opening .
As for to add sand part , when discharges are smaller , no matte how is the gradient the fishway have silt and silt in gush of flow , when discharges are increase , the gush of flow are decrease and improve silt condition .
In this research we probes into different interval of sand dunes in the fishway so that to know interval effect each section flow condition and silt in low water period , will provide design of inner structure for fishway .
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