Intercomparison of Simulated Groundwater Recharge from ISIMIP2b Models over Uganda

This study employs an ensemble of hydrological models from the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) over a 30-year period (1976-2005) to explore two questions: 1) what can we know about the historical recharge patterns over Uganda? and 2) how do these patterns compare with the same climate forcing? Preliminary results show that the annual recharge patterns vary spatially across the region with the same climate forcing, with a Northeast - Southwest gradient. Temporally, the models show distinct patterns across the four regions of Uganda with h08 and watergap2 showing similar patterns that are comparable to the ensemble mean under the same climate forcing. Generally, Ipjml and Jules-w1 hydrological models show opposite patterns compared to the other models and the ensemble mean, both spatially and temporally (with recharge values of less than 50mm/year). Given the limited groundwater observation networks over Uganda, these results highlight the potential role of ISIMIP models, in complementing the scanty in-situ observations for informing decisions geared towards sustainable groundwater management.