台灣地區的河川普遍有短流湍急的現象，導致降雨時期上游土石容易輸送至下游地 區造成淤積，更嚴重者則潰堤氾濫成災，2009 年8 月莫拉克颱風侵襲，即造成屏東縣林 邊地區的嚴重水患。在復原過程中，農業復耕受限於淤土沖積所造成的土壤性質改變， 以蓮霧為例，一般新植苗必須經過四年才有少量生產，更遑論土壤物理性質改變下的土 壤排水阻滯情況。 農田沖積土壤的剖面質地不均勻現象，易使剖面內部發生排水不良的問題，本專題 研究擬根據底土可供排水之粗砂質地層出現的深度、剖面中質地層理的分佈特性，以及 土壤管理組區分農地類型，並以流量軟體(PORFLOW)對各類型土壤在降雨過程中及降雨 停止後的水分動態變化進行模擬，確立各類型土壤的土壤水分管理情況，並依據各條件 特性研擬適當的農地排水改進方案。 運用模擬結果，於農地現地進行作物淹水逆境防護改善措施，並分析各類型土壤物 理性改良功效，期迅速減少大雨過後的土壤水分含量，且提高水分向下移動的速度，使 剖面內部排開較多的空氣孔隙。 Taiwan's rivers are generally short-turbulent flow. This feature was often easier to transport the debris upstream to downstream areas resulted in siltation in the rain period, the more serious was the dike flooded. August 2009, Typhoon Morakot caused serious flooding in Linbian township region, Pingtung County. In the process of agricultural recovery, rehabilitation was limited by the changed soil properties caused by fine alluvial soil texture. The new plant wax, for example, generally have only a few production after four years, let alone the drainage changed by the soil physical properties. The major agricultural lands are alluvial soils with interlaced texture stratification within the soil hindered downward movement of water and thus reduced the internal drainage rate. In the study, the soils were classified according as the depth of coarse sand layer and the proportion of coarse texture soil within the profile. Moreover, soil water movement of each soil category during and after rainfall were simulated by computer software (PORFLOW) for the consultation to improve internal drainage. The result of simulation could indicate the types of soil water management and develop the mitigation method by improving downward drainage methods. The efficiency of various proposed measures to mitigate water logging stress and damages to the crops. The mitigation techniques were expected to reduce topsoil water content, enhance downward seepage velocity, by removing more water through macropores of internal soil and leave air passages open.
