Optimal advanced release scheme based on effective forecast horizon to minimize flood at downstream of a hydroelectric project

Abstract

Dam-induced floods can generate sudden flash floods, creating potential cataclysms at downstream areas of a hydroelectric project. In the present study, we developed an adaptive flood management framework for controlling downstream floods of hydropower dams. Our work uses a simulation–optimization model to quantify advance release assuming perfect forecasts over diverse inflow forecast horizons (FH) before the arrival of the flood. The modelling framework consists of coupled reservoir operation and hydrodynamic models applied to an Inter Basin Water Transfer (IBWT) hydropower project. The novel methodology aims to determine the magnitude of advance release to minimize downstream flood levels without affecting power production. The generalized modeling framework was implemented in Ranganadi Hydropower Project (RHEP), Arunachal Pradesh, India. An uncertainty analysis was also conducted by incorporating multiple inflow sequences developed based on Monte Carlo Simulation into the coupled modelling framework. The model individually analyses each member of inflow sequences adopting a factor termed as the Flood Risk Factor (FRF) developed in the study. The Effective Forecast Horizon (EFH) was determined as the shortest FH that offers the highest level of reliability against floods. The results showed that in the case of a perfect forecast event, the methodology is successful in moderating the flood level to below the danger level. The analysis of different inflow scenarios also revealed that the EFH is highly sensitive to the inflow peak.