| Summary: | 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.
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