Departmental Bulletin Paper Study on Applicability of Overflow Discharge Equation Under Pressurized Flow Condition

KO, Dongwoo  ,  NAKAGAWA, Hajime  ,  KAWAIKEKenji

Recently, urban inundation disasters resulting from torrential rain have led to serious problems in many countries, especially in Asian countries. The numerous cities have been inundated by storm water, which is the major cause of urban flooding. To mitigate the damage of urban inundation, an underground storage box has been implemented. However, there are no criteria on the degree of mitigation effect that can be expected from such underground storage systems. In order to evaluate the mitigation effect, appropriate discharge must be diverted from a sewerage system over the side weir. Hence, during this study, the applicability of De Marchi’s equation in case of pressurized flow condition was validated using laboratory experiment results and suitable discharge coefficient was obtained for varying hydraulic conditions like weir length, weir height, etc. Finally, the numerical model was developed using one dimensional continuity and momentum equations with De Marchi’s equation as overflow equation. The numerical results show good agreement with the experimental results and empirical correlation for coefficient of discharge is proposed for the side weir.

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