| Summary: | 碩士 === 國立屏東科技大學 === 土木工程系碩士班 === 92 === Abstract
The objective of this study is to establish an optimized flow diversion model under the circumstance of minimum suspended sediments, and thereby evaluate the effectiveness of settling basins in Jia-Xian diversion weir. This report begins with a discussion of suspended sediments, turbidity testing and analysis of particle sizes in water. The relationships between flow rate, suspended sediments and turbidity, relevant operating rules of the flood gates and design data of settling basins were collected for Chisan River and Jia-Xian diversion weir to establish a foundation for an optimized flow diversion model. The report then introduced some theoretical framework of alignment planning and further discusses the analysis of an optimal time opportunity for flow diversion. At last, the effectiveness of settling basins was evaluated in terms of the results of the analysis.
The results of the analysis showed, the potential volume of flow diversion in year 2002 was 26.2% of the annual volume, and the optimal flow diverted was 15.6% of the annual volume. In year 2003, the potential volume of flow diversion was 18.9% and the optimal flow diverted for the year was 18.9%. With respect to the analysis and evaluation of the effectiveness of settling basins in Jia-Xian diversion weir, the results of this study indicated that in year 2002, the annual volume of suspended sediments in the diverted flow was 44,833 metric tons, of which the volume of sediments entrapped in the settling basins was 4,483 metric tons, while the volume of sediments that entered the reservoir was 40,350 metric tons. In year 2003 (January to November) the sediment in the diverted flow was 81,351 metric tons, of which the volume of sediments entrapped in the settling basin was 8,135 metric tons, and the volume of sediments entering the reservoir was 73,216 metric tons. Aggregating the above analysis results, the proportion of the potential flow diversion to annual diversion is relatively low. Examining the root causes of this finding, it was found that the quality of water diverted was limited to a maximum of 600NTU in this study. In consideration of the relationships between suspended sediments, turbidity of river course and flow rate, by improving the effectiveness of settling basins as a measure of reducing the volume of suspended sediments in the diverted flow into the channels, thereby increase the volume of reserve to provide for the operating needs of Nan-Hwa Dam, is a course for future studies
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