Potential of harvesting atmospheric water over urban cities in Kenya

Abstract

Most urban areas in Kenya are facing water crisis due to rapid population growth, industrialization and climate change. This study investigates potential of harvesting water from fog and air humidity over urban cities in Kenya. Daily air temperature, dew point temperature, wind direction and speed were used. Parameters including atmospheric water vapor pressure, saturated vapor pressure and the absolute and relative humidity of the atmosphere were derived. Air temperatures ranged between 18.2 and 27.6°C in urban areas. Mean annual foggy days was higher at Jomo Kenyatta International Airport (JKIA) with a maximum of 17 foggy days compared to other stations. However, mean annual harvesting days was higher at Moi International Airport (MIA) with a maximum of 350 days. Based on device efficiency of 10%, stations in Nairobi city (JKIA/Dagorretti Corner/Wilson Airport) indicated maximum water harvesting potential of 3.2/1.4/2.9 litres/m2/day in direction d6 (225 -270°) while Kisumu station showed highest potential of harvesting water (2.2 litres/m2/day) in direction d5 (180-225°). In Mombasa, the MIA and Lamu stations showed potential of harvesting 4.4 litres/m2/day and 3.9 litres/m2/day in direction d6 and d5 respectively. Based on monthly distribution of potential monthly water, harvesting from fog and air humidity was classified into either coastal or non-coastal/continental regions. The urban cities in Kenya have high potential of water harvesting from fog and air humidity presenting an alternative sustainable low cost approach to augmenting available fresh water sources and alleviating existing water stress. This will enable achievement of Kenya’s long term development footprint (Vision 2030) and Millennium Development Goals.