Household-Level Assessment of Urban Rooftop Rainwater Harvesting Potential and Its Contribution to Domestic Water Supply in Al-Wahdah District, Sana’a City, Yemen
Sana’a City faces severe water scarcity driven by limited rainfall, rapid urban growth, and groundwater overexploitation. This study assessed the potential contribution of rooftop rainwater harvesting (RTRWH) to domestic water supply in Al-Wahdah District, Sana’a City. The methodology integrated household survey data, GIS-based rooftop digitization, roof-material information, and monthly rainfall records for 2013–2022, with an average annual rainfall of 335.4 mm. Of 374 valid surveyed buildings, 277 residential buildings were analyzed after excluding 97 non-residential or unsuitable records. Domestic demand was estimated using observed (47.5 L/c/d) household consumption and the SWSLC benchmark of 61 L/c/d. Current RTRWH use was negligible, contributing less than 1% of consumption. Under a theoretical full rooftop utilization scenario, excluding storage constraints and first-flush losses, RTRWH could provide about 13,234 m3/year, equivalent to 19.6% of observed demand and 14.7% of estimated demand. Results show that RTRWH is a valuable supplementary source, but practical use requires storage and water-quality consideration.
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