Rooftop rainwater harvesting potential for kitchen gardening in the Rawal watershed, Pakistan

Conserving rainwater at the household level is generally overlooked in many developing countries. Therefore, rooftop rainwater potential for kitchen gardening or aquifer recharge was explored using 30 years of weather data in the Rawal watershed, which is facing water table decline (> 1 m/year) due to urbanization and climate change. The results revealed that harvesting rainwater from rooftops of available household sizes (single to five-room) in the Rawal watershed area is capable of growing vegetables (onion, tomato, cucumber, and garlic) on 25 (1 Marla) to 1339 m² (53 Marla) using storage tanks of suitable capacity (10 to 59 m³). Furthermore, by recharging the groundwater through the available rainwater of around 1.2 m per year can stop or reduce the current water table decline in the study area. Rainwater storage during the monsoon can increase productivity by reusing in dry periods while recharging aquifers can sustain flow from springs, dug wells, and tube wells in rural and urban areas. The new information and knowledge can be helpful for decision support in designing site-specific rooftop rainwater harvesting systems for kitchen gardening, which can be instrumental in improving food security and raising groundwater levels in both urban and rural areas.