| In this study, mid(Daedae-kyo) and down(Hoiya dam) streams of Hoiya dam basin are fixed as the analysis targets for application of AGNPS model according to real and probable rainfall, and probable flood and water quality change are predicted from the comparison and analysis of peak flow, sediment amount, and total nitrogen and phosphorus according to each of flow rainfall events. It is analyzed that existing rainfall distribution type is type II from the analysis of rainfall distribution type and time distribution pattern using Huff distribution method with rainfall data of Hoiya dam basin. Frequency analysis of each return period is performed to be utilized for probable flood estimation and water quality analysis, thus probable flood is estimated as Gumbel`s extreme value distribution. 35 grids are subdivided into 134 fine grids of finite differential net to analyze the peak flow, sediment amount, and nutrition materials of the basin, and peak flows of Daedae-kyo and Hoiya dam through the analysis by AGNPS model are 105∼142㎥/sec and 155∼218㎥/sec respectively. The corrected CN estimation equation shows good result for the relation of precipitation and peak flow. Estimated sediment amount of each rainfall event at Daedae-kyo and Hoiya dam basin shows 120∼170% of actual sediment amount. It is found that T-Ps of Daedae-kyo and Hoiya dam are reduced as much as 0.015∼0.041ppm and 0.012∼0.058ppm, and T-N of each location decreases 0.03∼0.54ppm and 0.1∼0.50ppm respectively from the analysis results of T-P and T-N according to actual rainfall in Hoiya dam area. Relatively good results appear through regression analysis of observed and computed data of actual flow, T-P, and T-N in Hoiya dam area, and T-P and T-N`s calculated values of probable rainfall show the tendency which is reduced as much as the probable flood is increased, but the reducing width of T-N is very greater than T-P. |
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