Study on the Habitat Suitability of River Cross Section via Physical Habitat Simulation Model

• Main Authors: Jia-Wen Syu, 許嘉文
• Other Authors: Ming-Young Jan
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/25618152309842485614

碩士 === 義守大學 === 土木與生態工程學系 === 104 === Due to the effect of climate change and uneven rainfall, main issues of river management focused on the flood control and water resources distribution. There are some weirs or dams built across the river bank without any consideration on the aqua-habitat properties that affected by various factors, such as velocity, depth or river bed materials. Ecological engineering and river ecology conservation became the hot study topics since 2000. In order to meet the requirement of aqua-habitat, “base flow” or “ecological base flow” is proposed as the guidelines during river management or water resources planning. One of the distinguished studies on river habitat conservation or restoration, weighted usable area (WUA) concept, was initiated by USGS. WUA considers the combination of velocity, depth, bed-materials and water temperature to simulate suitable area for the specific aqua-species in stream. Case study used in this paper is the reaches along Qishan River. Section properties (sectional profile, velocity, and discharge) from Bin-chiao to Chia-sian-chiao were collected. The suitable curve of red-trout and rainbow-trout were obtained from previous research report of Qishan River. Physical Habitat Simulation model (PHABSIM) developed by USGS is used in this paper to calculate the WUA under different flow rate and modification of cross section by groundsill works. Discharges from 30cms to 60cms are assumed as flow conditions, and grand sill raised river bed around 50cm~100cm are aligned as the river bed modification case. Results of the simulation show the WUA increased gradually by the increasing river flow. WUA is decreased due to groundsill at low flow, but increased rapidly at high flow. Since groundsill thwarts the river flow at high flow that makes more suitable zone for aqua-habitat. When the river flow depletes, some of habitat are replaced by concrete groundsill, and suitable area decreased.