以WinVAST模式探討降雨特性及土地利用對最佳管制作業去除機制影響

Abstract

暴雨初期沖刷是引起水質衝擊的關鍵時刻，在不同的降雨特性下，引起的汙染物對於水質濃度將產生影響，隨著點污染的逐漸控制，非點源污染問題日漸重要。往往由於暴雨所帶來污染物會隨著逕流的移動，造成污染的分散，以環境保育技術面，要降低污染發生，所謂的最佳管理作業(BMPs，如滯留池，草坡等)是常被使用的策略，在不同的土地利用情形下，因應不相同降雨特性，如何產生有效的配置以降低非點源污染，是值得探討的。 本研究首先蒐集國內外文獻資料，設計一假想集水區為研究標地，及模擬區域內土地利用，以組合不同的土地利用方式，作為研究分析的準備資料，並設計數種降雨型態，應用WinVAST模式資料庫及演算功能，模擬在不同降雨特性下，各污染物的濃度變化情形，之外，參考相關文獻設計一組合最佳管理措施(滯留池+草溝)，並配合設計不同的降雨型態，探討懸浮固體物污染物的去除效率。 根據研究結果，降雨特性大於土地利用的因子影響，但相乘作用下將放大集水區出流口的水量水質，在降雨特性的影響下，逕流歷線伴隨降雨的型態移動，水量越接近出水口而增加。進行BMPs設置時，可推求設置數量的合理化及配置方式優化，並取得經濟化配置設計效果。

First flush has been recognized as having the most critical impact on water quality. Each different storm rainfall characteristic conditions make different impacts on water quality. Usually there are some units as Detention pond and, Grassed waterway to prevented pollution extinction. In the case, try to change variables about rainfall types and land use. First, to search relationship studies about rainfall characteristics, land use, nonpoint pollution, and best management practical on papers. To use WinVAST model simulation, variables with papers results. As we knew, rainfall characteristics and land use were two majors on water quality and quantity in watershed. Besides, to combine BMP sys (Detention pond and, Grassed Waterway) and study Suspend Solid changes under rainfall characteristics and land use. According studies result, it is influenced that the rainfall characteristic is greater than the factor that the land use. The two causes will be enlarged quality and quantity in watershed outlet. Under the influence of rainfall characteristic, runoff hydrograph attitude is moved with the rainfall. As the same time, more the water yield is close to the outlet but increases. While setting up BMPs, increasing the quantity of setting up can be inquired. But dispose and look with economy, design better result in disposition on the major river.