Evaluation of parameterisation approaches for estimating soil hydraulic parameters with HYDRUS-1D in the groundnut basin of Senegal.

Soil hydraulic parameters (SHPs) required as inputs for numerical models are scarce in Sahelian regions. Instead, they are estimated using pedotransfer functions (PTFs), but their ability to simulate soil water dynamics has not been evaluated. This study aims to parameterize SHPs with seven different PTFs and inverse modelling to examine their ability to simulate water fluxes in Senegal's Groundnut basin. We used four years of field measurements of soil water content (SWC) and actual evapotranspiration (ETa) under pearl millet and groundnut crop rotation for model evaluation. Inverse modelling for SWC (root mean square error [RMSE] ≤ 0.015 cm3 cm−3) and ETa (RMSE ≤ 0.62 mm d−1) yielded the best model performance compared to PTFs (0.024–0.175 cm3 cm−3 and 0.68–0.96 mm d−1, respectively). Where field measurements are lacking for inverse estimation, three of the seven tested PTFs yielded good modelling results and could be used as a parsimonious approach for cultivated Sahelian soils. [ABSTRACT FROM AUTHOR]