The Study of Quantitative Assessment and Improvement Methods in Ameliorating River Ecology In Taiwan

• Main Authors: Chen-Tai Mao, 毛振泰
• Other Authors: Ray-Shyan Wu
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/68343739062937219967

博士 === 國立中央大學 === 土木工程研究所 === 95 === With the aim to resolve problems in quantifying ecological and hydrological aspects of water works engineering and design, this study applies data on fish species from the “Freshwater and estuarine fishes of Taiwan”, “The Fish Database of Taiwan “ from the Center for Biodiversity, Academia Sinica, and international scientific literature to fit four different habitat suitability curve regimes (flow velocity, water depth, bed material and water quality) of the upstream, midstream and downstream sections of rivers in five different geographical zones in Taiwan. In total, 60 habitat suitability curves for local endemic freshwater water species were drawn and used as the standard to assess river habitat ecology. This methodology was applied for different river channel types in Fatze River and a quantitative analysis was carried out for ecological width and sinuosity typical of rivers in Taiwan. The conclusions derived from our study can be summarized as follows: 1.The analysis on different river channel types in Fatze River shows that river width and channel form design both affect habitat area. Widening the river channel will increase river habitat area and traditionally methods in designing a complex cross-sectional relief are most efficient in maintaining habitat area. The more complex the design of the river channel sinuosity also increases habitat area for endemic fish species under certain discharge velocities. Once discharge exceeds Q50, the floodwater top the riverbanks and create optimal habitat conditions for the freshwater fish species. This conclusion is also visually corroborated by the presence of fishermen up and down the river coasts once a typhoon passes. 2.Following the analysis of 32 river sections and their habitat types in Taiwan, we concluded that for the future construction and amelioration of river embankments a minimum of 70% of the original channel width must be reserved for river ecology (Be). The landscape and topographical relief of the river must remain untouched. Additionally, for river sections in need of new floodworks construction, our study recommends that the largest value of the river width equation be used for regulating the project width (Bp). Furthermore, the relationship between Be and Bp should be established at Be=0.1324* Bp1.1931 to calculate the requisite minimum width of the river to maintain base ecology. 3.The analysis of the river sinuosity in 11 meanderings of the 32 rivers has confirmed that of the hydraulic geometric relationships obtained by Leopold and Wolman (1960), the equation for the distance between two meanders（λ）is applicable to Taiwan while the equations for amplitude and radius of the meander are not. The region outside of the river bend is a suitable habitat area during floods and, as such, by river management guidelines should be protected and preserved. 4.In situ observation and application of habitat suitability curves from previous studies targeted a single fish species and were constrained by physical limitations. In the future, the use of underwater long-term video cameras and datalinks for immediate computer analysis is recommended for field trials. 5.The results achieved in this study can used as a reference by government bodies involved in large-scale water works engineering projects (e.g. the Homeland Restoration Project and the Regulation of Flood-Prone Areas Project). It can be a functional tool in eco-engineering, and facilitate the implementation of ecological concepts in engineering and construction work.