TITLE:
Rain-Flow Modelling Using the GR4J Model for Flood Risk Management in the Oti Watershed (Togo)
AUTHORS:
Koungbanane Dambré, Kodja Japhet Domiho, Lemou Faya, Totin Vodounon Henri Sourou, Amoussou Ernest
KEYWORDS:
Modeling, Génie Rural à 4 Paramètres Journaliers (GR4J), Floods, Kling-Gupta Efficiency (KGE), Oti Watershed, Risk
JOURNAL NAME:
Open Journal of Modern Hydrology,
Vol.14 No.4,
October
30,
2024
ABSTRACT: In recent years, West Africa has been confronted with hydro-climatic disasters causing crises in both urban and rural areas. The tragedy in the occurrence of such events lies in the recurrent aspect of high water and associated floods. The devastating floods observed in Africa’s major rivers have revealed the need to understand the causes of these phenomena and to predict their behavior in order to improve the safety of exposed people and property. The aim of this study is to reproduce flood flows using the GR4J (Rural Engineering Four Daily Parameters) model to analyze flood risk in the Oti watershed in Togo. Daily data on flows (m3/s), potential evapotranspiration (mm/day) and average precipitation (mm) over the basin from 1961-2022 collected at the National Meteorological Agency of Togo (ANAMET) and the Department of Water Resources in Lome, were used with the R software package airGR. The Data from the West African Cordex program from 1961-2100 were used to analyze projected flows. The results obtained show the GR4J model’s effectiveness in reproducing flood flows, indicating that observed flows are well simulated during the calibration and validation periods, with KGE values ranging from 0.73 to 0.85 at calibration and 0.62 to 0.81 at validation. These KGE values reflect the good performance of the GR4J model in simulating flood flows in the watershed. However, a deterioration in the KGE value was observed over the second validation period. Under these conditions, there may be false or missed alerts for flood prediction, and the use of this model should be treated with the utmost caution for decision-support purposes.