| Summary: | 博士 === 國立中興大學 === 水土保持學系所 === 98 === Extreme events, resulted from climate change, caused wide variation in the flow of river and creeks, not only in frequency of high flow period being found decreased, but also flow fluctuated substantially.As low flow period prolonged, the exposed river banks and riverbed expanded. Sand-stilling work became a major concern to the neighborhood.
Peinan River, One of the main rivers and creeks in the east of Taiwan, has been found an wide flow difference in low flood period and dry season; its riverbed exposed to a wider area in dry season. The sand swept by the wind often shrouded low plain area on both sides of Peinan River during the gale period,forming serious sand dust hazard, earned Taitung city nicknamed as “ The sand city”.
The study deducted that to cover three major categories of river profiles, namely, “water-covered area”, “vegetation-covered area”, and “exposed area”, study approaches were documentation research, hydrological investigation, ecological investigation, build-up of river profiling numerical models, site experimentation, and numerical simulation, etc. The objective of this study is to explore the causes of wind-induced wind dust hazard, the mitigation methods by either an alternated layouts of “water cover”, “vegetation cover”, and “riprap armor cover” on flood belt, or simulaneously a creation a river environment with ecological conservation measures. Thus not only an ecologically-friendly river environment could be created, dust hazard also mitigated.
This study aims using Peinan River as sample to lead to an overall strategy for river profiling management, at the same time, to conduct an review of river profile environment with an index of performance “River Geomorphy Environment Index” (IOP). IOP is used to compare different river systems. This index put various weights on the total area of water cover area, vegetation cover area, riprap armor area. amd its ratio to the total river area. Index quantify from 0 to 5 grades, with 5 as top grade, and needing profiling modification for grade under 3. Details, both evaluation and approaches, on 3 said river profile modification measures, were presented, and proved it is technically feasible for river profile area maintenance and improvement.
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