由深度面积体积等物理量曾文水库集水区莫-中华水土保持学会.pdfVIP

2012 年中華水土保持學會年會及學術研討會論文集 1 由深度面積體積等物理量評估曾文水庫集水區莫拉克颱 風後龍蛟溪土砂治理成效 [1*] [1] [2] [3] [4] [4] 何幸娟 林伯勳 張玉粦 冀樹勇 簡以達 蔡明發 摘 要 本文藉由蒐集集水區依時性監測數據及多時期遙測資訊，分就深度、面積、體積等三個易 於量測物理量，逐次研析土壤沖蝕、崩塌區域、土砂控制量等課題，藉以評估治理工程施作後對於「土 砂生產」及「土砂流出」之控制體積量，實質量化治理前後地形貌變化情況以及治理成效。分析結果 顯示，龍蛟溪集水區自99 年5 月南部地區供水計畫啟動迄民國 100 年 12 月(約計2 年) ，由人為治 理後邊坡相較於裸露邊坡沖蝕厚度，約能抑制61.2%表土流失；坡面崩塌裸露地面積於2 年期間，由 16.73ha 降低至5.37ha(莫拉克颱風後至南瑪都颱風後) ；且於治理前後，龍蛟溪集水區土砂遞移率由 97.8%(民國97 年至99 年)降低為62.2%(民國99 年至 100年) ，顯示水土保持措施已確實發揮功能， 可有效抑止土砂生產與流失。 關鍵詞：曾文水庫、成效評估、土砂生產。 Evaluation of Remediation Efficiency for the Longjiao Creek in Tseng-Wen Reservoir Watershed after Typhoon Morakot Based on the Phiysical Quanity of Depth-Area-Voloume Hsing-Chuan Ho[1*] Bor-Shiun Lin[1] Yu-Lin Chang[2] Shu-Yuon Chi[3] Yi-Da Chien[4] Ming-Fa Tsai[4] ABSTRACT This paper systematically studies and analyzes soil erosion, landslide areas, and sediment control volume. from easily measured physical quantities such as depth, area, and volume by collecting time-dependent monitoring data and multi-temporal remote sensing information in a watershed scale. The result is then used assess the controlled volumes of sediment production and sediment loss after the remediation works. Analysis shows from implementation of water-supply program for southern Taiwan in May 2010 till December 2011 (about 2 years), remedied slopes have less erosion depth than non- remedied slopes, and around 61.2% fine soil content were prevented. During this period, the total landslide area had been reduced from 16.73ha to 5.37ha (from post Typhoon Morakot to post Typhoon Nanmadol). Since the remediation, the Longji