EVALUATING THE PARFLOW-CLM INTEGRATED MODEL IN ONE DIMENSION: REVISITING WATER AND ENERGY BUDGETS IN THE CULTIVATED SAHEL (WANKAMA, NIGER)

This study evaluates the integrated hydrological model Par Flow CLM (PF-CLM) in a 1-D configuration over two Sahelian agro-ecosystems (rainfed millet and fallow bush) at Wankama, Niger, using 2006,2011 in-situ forcing and observations data. The soil column is discretized into five horizons with a crusted surface layer; key hydraulic (Ks, a, n) and radiative (albedo) parameters are calibrated via Latin Hypercube sampling against evapotranspiration onset, runoff coefficients, and albedo dynamics. Kling-Gupta Efficient (KGE), correlation, and Nash Sutcliffe efficiency (NSE) are used to evaluate model performance. The results showed that PF-CLM reproduces surface energy fluxes with good skill (KGE 0.75 0.80 for Rn and LE) and captures seasonal wetting drying cycles in near-surface soil moisture (KGE 0.65, 0.81 at 10,50 cm), with performance decreasing at depth, especially under fallow. Annual water budgets are realistic: evapotranspiration accounts on average for 82% (millet) and 88% (fallow) of rainfall; runoff represents 16% and 13%, and deep drainage is negligible to slightly negative (0 to 2% of P). Par Flow CLM produces higher runoff, slightly lower evaporation, and limited but non-zero vertical redistribution within the soil profile, rather than effective downward percolation. These results support the use of PF-CLM for process studies and for scaling to 2-D hillslopes to assess sustainable land-management impacts on infiltration runoff partitioning and recharge in the Sahel.