Effect of rainfall spatial variation on the non-point source pollution loading estimation

• Main Authors: Yih Chyun Lin, 林逸群
• Other Authors: J.-J. Kao
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/43233636012211051937

碩士 === 國立交通大學 === 環境工程所 === 89 === Rainfall is one of the most important departments counting NPSP because of the extent of NPSP generated from catchment areas surrounding a reservoir is normally estimated based on a design rainfall. However, rainfall generally varies in different space. This spatial change may significantly influence the estimation of runoff volume and associated NPSP arising within a reservoir watershed. The NPSP management, reservoir operation, and water treatment operation strategies developed based on the estimation will also be altered. This study therefore analyzes the effects of spatial variation in precipitation on the estimation of pollution levels from non-point sources in a reservoir watershed. We use three common methods Thiessen polygun, the inverse distance and K-nearest-neighborhood to analysis the difference of rainfall spatial variation and differs the differences between the NPSP. The NPSP is counting form one event AGNPS model. The Derchi reservoir watershed located in central Taiwan, R.O.C. is the area studied. Precipitation data monitored at 10 gauge stations and 26 and 56 sub-watersheds are used to assess the spatial rainfall variations and NPSP within the watershed. According to the results obtained in this study, because of according to the nearest rain gauge, the Thiessen method have the largest spatial variation. Many rainfall events have obvious spatial variations effecting the variations of NPSP. It’s not good using one value rainfall to count the NPSP. Spatial variations of rainfall effect the sort of NPSP value arising form each sub-watershed and will effect the decision of watershed controls . Because of getting real NPSP and having the right watershed control, we should consider the rainfall spatial variation. This time series also influence the estimation of NPSP arising within a reservoir watershed. This study therefore analyzes the effects of monthly and seasonal variation in precipitation on the estimation of pollution levels from non-point sources in a reservoir watershed. Because of the result is not good, we put it in appendixes.