TITLE:
Physically Based Hydrological Simulation of the Bia Transboundary Catchment (West Africa)
AUTHORS:
Blé Anouma Fhorest Yao, Gneneyougo Emile Soro, Francis Marie Colson Beniambie, N’Guessan Kouamé Emmanuel Abo, Almami Daifourou Kansaye, Bi Tra Anderson Ba, Bi Tié Albert Goula
KEYWORDS:
Land-Cover, Runoff, SWAT Model, BIA Catchment, C?te d’Ivoire
JOURNAL NAME:
Open Journal of Modern Hydrology,
Vol.16 No.3,
June
23,
2026
ABSTRACT: Understanding all the components of the water balance is essential for rational and sustainable management of water resources. However, direct assessment of several components of the water balance is very difficult and modelling is often necessary. The main objective of this study is to simulate the hydrological functioning of the Bia catchment upstream of lake Ayamé. To achieve this objective, this study is based on data processing (meteorological, hydrological and satellite data from 1982 to 2020) to describe the natural characteristics of the basin. Soil and Water Assessment Tool (SWAT) model implemented in Quantum Geographic Information System (Qgis) was used for the analysis and modelling of hydrological processes at catchment level. Analysis of satellite imagery reveals a significant decline of 46.10% in vegetation cover, with an increase in agricultural land, degraded forests, bare soil and built-up areas. This decline has affected the surface area of water bodies in the basin, with a 70.15% reduction over the period 1987-2017. SWAT model showed good performance (78% for calibration and 60% for validation) in reproducing the monthly flows of the river Bia at Bianoua. The annual balance shows high actual evapotranspiration (614.7 mm/year, or 66% of rainfall) in a basin that receives 921.3 mm/year of rainfall. Surface runoff accounts for 17.5% of rainfall and infiltration 16.7%. Volumes of precipitated water have suffered enormous losses due to high rates of actual evapotranspiration. Despite this, the balance remains acceptable across the basin, as rainfall exceeds actual evapotranspiration.