浊水溪下游段河性分析与治理对策

Stream Characteristic Analysis and Remediation Strategies at Downstream of Zhuoshui River

台湾地区随着国民生活水准提升,都市土地充分利用后,有关河川之治水、利水、亲水、保水、活水等功能渐受沿岸居民重视。目前浊水溪下游段深水槽经调查发现已严重下陷约6 m,当历经桃芝台风时其洪峰流量29 000cm s远超过100年洪水频率之洪峰流量24 000 cm s,亦超过洪水频率200年之洪峰流量27 000 cm s,但是下游段河防构造物却未受到任何损坏,反而集集拦河堰上游之陈有兰溪及南清水沟溪受到土石流严重的侵袭,造成人民生命财产重大的损失。探究原由乃是通洪断面增加,深水槽流路稳定,洪水未冲击堤防所致,故将检视浊水溪下游河段治理计划之合理性,探讨可否将以往浊水溪治理计划之两段式复式断面,因势利导致为三段式复式断面布置,更能符合河川治理之经济性、稳定性、可行性等需求。

The living standard is promoted and the city land is fully utilized in Taiwan,the residents along rivers gradually pay attention to regulating water, utilizing water, communing water, protecting water and running water. At present the deepwater trough at the downstream of Zhuoshui River has sunk seriously about 6 m since experiencing over the typhoon Taozhi with 29 000 cms of flood peak which goes beyond the 24 000 cms of flood peak under 100 years of flood frequency and also the 27 000 cms of flood peak under 200 years of flood frequency. There is no damage in the flood-prevention structures at the downstream of Zhuoshui River. However the great losses of people＇s life and properties were caused by the debris flow on the Chenyoulan river and Nanqingshuigou river at the upstream of Jill weir. The reason is that the flowing section is increased at the downstream of rivers and the deep-water trough flows steadily on the way to cause the flood not to strike the dyke directly. The rationality of regulating water at the downstream of Zhuoshui River is evaluated and the feasibility from twostaged polymorphous section to three-staged polymorphous section in the past restoration plan of Zhuoshuei River is discussed. With the summarized analysis results, it is found that the three-staged polymorphous section can meet the requirements in economy,stability and feasibility in the river＇s harness.