In this study the potential impacts of two strategies, namely in situ water harvesting (in situ WH) and fertilisation with stored human urine (Ecosan), to increase the water and nutrient availability in rain-fed smallholder agriculture in South Africa"s Thukela River basin (29,000 km2) were explored. The Soil and Water Assessment Tool (SWAT) was used to simulate potential impacts on smallholder maize yields, river flow regimes, plant transpiration, and soil and canopy evaporation from 1997 to 2006.