An Experimental Study of Hydraulic and Sediment Transport Characteristics for Fish-Bone-Type Fishway

• Main Authors: Shun-Chang Wang, 王順昌
• Other Authors: Su-Chin Chen
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/22395427910576256419

碩士 === 國立中興大學 === 水土保持學系 === 90 === The established sabo dams used to less thoroughly protect fish ecology in Taiwan. Even though they set up use a “pool and weir type” fishway in most cases, but the disadvantage of this type of fishway is easily to develop sediment deposit or collide with a powerful current. Because of lacking understanding to the characteristics of indigenous fish ecology by researchers, the fishway usually results in failure and falls into disuse with minimal research evaluation after it’s establishment. Hu(2001) has conducted an experiment of fish migration by using various types of fishway. He focused on some indigenous fish species, such as Varicorhinus alticorpus and Acrossocheilus paradoxus etc. The result indicated that the fish-bone-type fishway (refining Larinier type) provides usage for more fish species, and the best migration gradient of fish is 1/8. For removing sediment, Hu poured into the entry of upper stream of fishway by using 16kg of constructing sediment only. After cleansing for 24 hours with 0.048cms discharge, 87% of sediment was removed. But the investigation of hydraulic and sediment transport characteristics was not done. Thus, this study is an experimental research of hydraulic and sediment transport characteristics for fish-bone-type fishway by using the model. For the purpose, it is to understand the mechanism of hydraulic and sediment transport. Also, the design of a fish-bone-type fishway is established based upon such a scheme. Finding is used to provide a better fishway for the indigenous fish species in Taiwan. Three flow rates (0.016cms, 0.032cms and 0.048cms) and two gradients (1/8 and 1/10) are considered in this model. Because of Rapidly-varied flow in the fishway and the instability of the flow field, the average flow rate is calculated by measuring the depth of water. Two average granule diameters of adding sediment are 9.27mm and 10.77mm. The total experimental time is 200 minutes─100 minutes for adding sediment and 100 minutes for water cleansing. Result indicates that rating curve(discharge VS water level) is almost overlapping at the water depth of gradient 1/8 and 1/10 in front and upper weir. The flow rate is calculated by successive formula Q=AV. For the gradient 1/8, sediment of the fishway is reached to a balance of transporting after 30-40 minutes experimental time. The rate of sediment removal of the fishway is above 97%, and the residual sediment is below 3%. For the gradient 1/10, sediment of the fishway is reached to a balance of transporting after 20-50 minutes experimental time. The rate of sediment removal of the fishway is above 93.5%, and the residual sediment is below 6.5%. The appropriateness of fish-bone-type fishway design will affect the efficiency of removing sediment. The result indicates that the better sections of removing sediment are location 2, 5, 7, 10, 12, and 15. These locations have less and even no sediment deposit. The better sections of depositing sediment are location 1, 3, 6, 8, 11, 13, and 14. The result also indicates that the better gradient of removing sediment is 1/8, which is the same as previous research studies of maximal sail upstream gradient of fish. The result can be used to build an on-site formula of discharge rating as well as providing a reference resource for the on-site experiment and evaluation of the design.