The Influence to Channel Transition of Dam Removal：A Case Study of Baling Dam
Date Issued
2009
Date
2009
Author(s)
Lin, Hsin-Yi
Abstract
Based on structure safety and environmental & ecological consideration, dam removal becomes a hot public topic in recent years. And there are many practical experiences of dam removal in the world. In Taiwan, this is still a new issue to hydraulic research. However, in 18 September 2007, Baling dam in Tahen River was broken suddenly in the afternoon. This event provides a great chance to understand dam removal. So, this study will execute mobile-bed sediment transport numerical calculation and simulation to the upper and below 5 km of Baling dam and use NETSTARS which is a quasi-two-dimensional model to study the effect to riverbed and fish habitat after dam removal.fter finishing upper numerical calculation and simulation, this study can get a riverbed stability index (K). Also it found that if Baling dam broke (it seems like removing it once for all), the riverbed takes 2 years to reach stable and balance status; but under the assumption of removing the dam for two steps, it takes 4 years. And when we remove the dam for two steps, its K-value is larger than we remove it one for all. In the end, this study finds that no matter how we remove the dam, K-value is always between (1.4?2)x104.esides, this study can know that different time-interval of removing the dam is not the major reason to cause the different riverbed variation. Actually, the most important factor is that if there’s a flood in the middle of 2 dam-removing steps. Therefore, to engineering practice, it’s better to choose drought period to remove the dam.n this research, this study also uses statistic test analysis to find the effect to fish habitat after removing dam. No matter it’s before dam-breaking, after dam-breaking, or we remove it for two steps, there is no obvious effect to Habitat Suitability Index (HSI) of Cyprinidae, Gobiidae, and Homalopteridae. But one thing is sure that after dam removal, the habitat and migration area of fish will increase. Also they can avoid the crisis of incest breeding. So, how to amend the habitat and create an environment that is suitable to fish is the first priority work in the future.
Subjects
Baling dam
dam removal
riverbed stability index
habitat suitability index (HSI)
Type
thesis
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