Estimation of the Flood Discharge Considering the Hydrological Characteristics of Urban Stream in Island area
Abstract
1. Background/ Objectives and Goals
The streams of Jeju Island, at the southernmost of Korea, have very different hydrogeological features from those of the inland areas, but the same method applied to the inland areas is applied to the calculation of design flood amount in the stream basic plan established to reduce the flood damages of the watershed, which is problematic. This study drew the optimal parameters considering the hydrological features of Jeju Island based on the flux data observed on the stream sites in order to calculate the flood amount appropriate for Jeju streams. 2. Methods This study proposed a formula that can consider for inclinations when calculating CN by considering the watershed features with high inclination and conducted re-calculation, and based on the on-site observation data, conducted regression analysis of time of concentration and drew the new calculation formula for time of concentration. Also, as the land use and soil map according to altitudes and geological features are clearly sorted, the flood amount after the small watershed division was compared and reviewed. The calculated flood amount was compared and reviewed against the on-site observation data acquired with Kalesto and fixed-type water level and portable fixed electromagnetic wave surface velocimetry. 3. Expected Results/ Conclusion/ Contribution When the CN value considering the inclination of Jeju urban streams was corrected. the accuracy of peak rate of runoff was increased by 1.5~6.4% according to the runoff mapping. As the flow speed exceeded 7m/s during the flood runoff of Jeju stream, it was impossible to apply the existing formula for time of concentration. Accordingly, a new time of concentration was calculated reflecting the Jeju stream features, and when compared to the design flood amount calculation guideline, the accuracy of the peak rate of runoff was increased by 3.5~16.7%. The small watersheds were divided to calculated the flood amount, and the accuracy of the peak rate of runoff was increased by 11.5~37.6% compared to the existing method. Thus, when the flood amount was calculated with the combination of the optimal parameters, the accuracy of the peak rate of runoff was increased by 1.2~28.8%.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H41N1902Y
- Keywords:
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- 1803 Anthropogenic effects;
- HYDROLOGY;
- 1821 Floods;
- HYDROLOGY;
- 1825 Geomorphology: fluvial;
- HYDROLOGY;
- 4303 Hydrological;
- NATURAL HAZARDS