Flood Hazard Assessment of Water-Front Geosynthetic Reinforced Soil Wall for Dam Regulation Rule Level

Abstract

The flood hazard parameter of peak discharge and prolonged inundation due to change in dam regulation is estimated for a water front Geosynthetic Reinforced Soil (GRS) wall on the downstream of large dam. Dam regulation rule level is pre-emptying the reservoir with lower peak discharge to protect the expanding downstream city intruding the flood plain. Present study is to test the hypothesis that rule level has significantly changed peak discharge and inundation duration and also to estimate these two important parameters of flood hazard for different flood return periods. The methodology consists of three parts: first is the categorization of flood data according to major event of flood regulation, second is the distribution test and third is the estimation of design maximum peak discharge and duration of flood. The estimated value of peak discharge and flood duration clearly indicate the implication of dam regulation rule level; the estimated value of peak discharge for 200 years return period is 13.9 lakh Cusecs, which is lower than the flood discharge for year 1968, which was 15 lakh Cusecs, and the estimated flood duration for 10 years return period is 41 days. The most important finding of this study is the substantial increase in duration of flood due to implementation of rule level which will add one more flood hazard parameter for water front geotechnical structure that is prolonged inundation.