Data Sheet 1_Soil and Water Assessment Tool reveals dominant baseflow in semi-arid catchment with sand dams in Kenya.docx

Under RCP4.5, increased precipitation is partitioned predominantly into enhanced percolation and subsurface flow, strengthening the modeled baseflow contribution while also increasing localized surface-runoff peaks. Representing sand dams as standard reservoir objects enabled the analysis of spatial and seasonal differences among individual structures and their cascade behavior, but produced highly episodic storage dynamics and substantial quantitative uncertainty.</p>Discussion<p>The results demonstrate the potential of open-data-supported hydrological modeling for characterizing ungauged semi-arid catchments and exploring sand-dam networks at the catchment scale.

At the same time, the SWAT+ reservoir formulation cannot adequately reproduce key sand-dam processes, particularly porous-media storage and sediment-related subsurface dynamics. The findings should therefore be interpreted primarily in terms of hydrological patterns and model behavior and not as as precise estimates of sand-dam performance, highlighting the need for improved model representation and field-based validation.</p>