First flush analysis of agricultural non-point source

• Main Authors: Ming-Kei Leung, 梁銘基
• Other Authors: Ching-Gung Wen
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/46935419760533270469

碩士 === 國立成功大學 === 環境工程學系碩博士班 === 96 === Stormwater runoff was monitored on 6 separate agricultural watersheds, which were chosen to represent distinct types of farming and spreading chicken fields, along with various watershed characteristics. A total of 57 storm events were monitored to investigate the first flush phenomenon. There are two first flush phenomenon definition, one is concentration first flush(CFF), another is mass first flush(MFF). CFF may be defined as the initial period of stormwater runoff during which the concentration of pollutants is substantially higher than during later stages. MFF may be defined as the initial period of stormwater runoff during which the quality of pollutants throughout the majority of the pollution load. The magnitude of the first flush phenomenon was calculated using a method of data analysis which results in determining the dynamics event mean concentration ratio(REMC) and mass first flush ratio(MFFn). In addition, statistical and graphical correlation analysis of the REMC and MFFn with storm characteristics and environmental factors was made to determine if the first flush is related to site or storm characteristics. As the results, although the percentage of impervious area near zero, we can still be found strength to moderate concentration first flush phenomenon and moderate to mild mass first flush phenomenon in agricultural area. The results and analyses performed also indicates that the concentration first flush phenomenon of SS,COD and TP correlate well with total rainfall, total runoff and rain time but there are no correlation between the mass first flush phenomenon. No correlation was observed between the first flush phenomenon and area, slope and porosity. In this study, through cluster analysis proved that the first flush phenomenon in agricultural areas occurred mainly on non-soluble pollutants.