本研究3年內定期觀測士文溪87次、全洪程觀測7次,計得洪水流量資料217筆、例行觀測流量87筆;研究中發現河床變化除主深槽抬升近一公尺外,可能會對右岸護岸造成淘刷。依據觀測所測之河床高程資料判斷,洪水期間河床底變化易發生於橋墩周圍。例行觀測中,最大流速發生在2011年,觀測值為2.98m/s;最大流量發生在2012年,其值為94.97cms。全洪程觀測最大流量發生在2011年的南瑪督颱風,觀測所得流速為5.00m/s,產生的流量達423.14cms,觀測時間最短15小時,最長57小時。 以2011年至2013年共3年觀測期間內,觀測最大流量423.14cms所對應之水位40.38m進行計算,2011年例行觀測之流量為1103.01cms、全洪程流量為518.27cms,全年觀測迴歸之流量為603.52cms;2012年全洪程流量為536.85cms,全年觀測迴歸之流量為768.56cms;2013年例行觀測流量為644.17cms、全洪程流量為70.50cms,全年觀測迴歸之流量為36.34cms。由分析顯示底床變動後必須重新進行水位-流量率定曲線之率定。2013年8月22日河道橫斷面面積為43.525m2,而天兔颱風事件後河道橫斷面面積為61.625m2,面積增加41.59%,淤積最嚴重位置約為斷面90公尺處,淤積0.9m;沖刷最嚴重處為斷面110公尺處,沖刷深度為0.18m。左岸橋墩淤積約0.9公尺造成主河道變動,可能會對右岸護岸造成淘刷。
In this study, Shi-Wen Creek persist 3-years regular observations 87 times, high flow discharges observed 7 times which total have 217 flood flow data, and the regular observations 87. During the study we found the main channel bed uplift changes nearly a meter, and that may scour the right bank revetment, Based on the regular observations, the maximum flow rate occurred in 2011, value was 2.98m/s, and 94.97cms in 2012. In addition, the maximum flow of High observing in Typhoon Nanmadol 2011. We generated flow rate up to 423.14cms, the longest observing are 57 hours and the shortest is 15 hours. Taking the Maximum flow 423.14cms corresponding water level 40.38m to count, we got the flow in 2011 amounted to routine observation is 1103.01cms, high flow discharges observe is 518.27cms, the whole year analysis of regression flows is 603.52cms. In 2012 routine observations flow is 536.85cms, the whole year analysis of regression flows is 768.56cms. In 2013 routine observation flow is 644.17 cms, high flow discharges observe is 70.50cms, the whole year analysis of regression flows as 36.34cms. Indicated by analysis shows the rating curve must be re- calibration after the riverbed changed. August 22, 2013 the river cross-sectional area is 43.525m2, but after Typhoon Usagi the river cross-sectional area is 61.625m2, which increased 41.59%. Furthermore, the most serious siltation located in 90m section, siltation 0.9 m, dig brush worst place to section 110 meters, brush dig depth 0.18m. As a result the left bank of the pier about 0.9 meters siltation caused changes in the main river, the right bank revetment might be caused by scouring brush.