A study on estimation of the ecological instream flow and improvement of habitat for midstream on Dahan river

• Main Authors: Jing-Wei Xie, 謝暻椲
• Other Authors: Ray-Shina Wu
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/11514779650208354185

碩士 === 國立中央大學 === 土木工程研究所 === 90 === This paper combines hydraulic model HEC-RAS 3.0 and habitat model RHABSIM 2.2 to calculate the ecological instream flow of the habitat by using Acrossocheilus paradoxus as target species in the midstream of Dahan river. Different influence from a high-weir or a series of low-weirs in research area was analyzed. The change of habitat and the economical benefit of weirs were also discussed. Analysis of RHABSIM model to habitat in the condition of low flow was performed. To achieve ecological requirement, the instream flow is estimated to be 16 cms. However, 3cms is proposed to be an adequate alternative given economical consideration of shortage in water resource in this region. It is concluded that building the weir in the river, in the condition of low flow makes the habitat area increase. In other words, the structures play an important role in augmenting habitat. Besides, one may notice that the height of weir and the area of habitat are not in direct proportion. Setting a series of low-weirs is better than setting high-weir in some conditions in terms of providing habitat area. Therefore, it is suggested that habitat condition can be improved by using the combination of proper series of low-weirs. A policymaker can provide the water to the institutions in need by choosing the weir setting which produces the highest economical benefit.