| Summary: | 碩士 === 國立中興大學 === 水土保持學系所 === 100 === In Taiwan, the development of water resource mainly comes from three sources ----reservoirs, river water and ground water. Although reservoirs provide the advantage of preventing floods during flood seasons, the suitable construction site for a reservoir is hard to find, not to mention the impact of ecology .Further more, the result of using ground water often causes problems of land subsidence.
So obtaining water resource of river is the only way to develop in Taiwan. Usually, by knowledge of gravity, people have made river diversions to irrigate land for centuries since the early history of mankind began. However, because of the limitations of special geographical factors in Taiwan such as small size of land area, dense population, short distance and fast-flowing water of rivers and longer dry seasons, it is difficult to access water resource from rivers unless people apply three practical approaches to the work of water intake by using stone baskets, gabions and weirs. As a result, the rising water level of rivers makes it feasible to constantly obtain water resource from rivers.
Therefore, weir construction becomes important particularly, so this study is aimed at proposing solutions to improve the overall project planning and designs for weir constructions. Meanwhile, the idea presented in the study is prepared for not only meeting the challenge of the global environmental changes but also achieving objectives such as extending the lifespan of weirs, using hydraulic de-silting to replenish the sand sources of rivers in the downstream and coast lines, slowing down the process of erosions of rivers and coast lines and lastly providing minimum demand of water to maintain the ecology of rivers.
At the same time, giving the Da-Du weir which would be located in the central Taiwan as an example, the study goes further in detail to discuss about the plan and design of weirs covering a broader range of related engineering facilities from weir, water intake works, Parshall Flumes, sediment basins to fishways. Subsequently, the results of the study would provide valuable suggestions for interesting parties that might need it as reference to make decisions when confronted with issues of such weir projects in the future.
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