Rooftop dew, fog and rain collection in southwest Morocco and predictive dew modeling using neural networks

Two coastal sites were investigated in an arid region of southwest Morocco to determine the amount of dew, fog and rain that could be collected from rooftops for household use. Systematic measurements were performed in Mirleft (43 m asl, 200 m from the coast) for 1 year (May 1, 2007 to April 30, 2008) and in Id Ouasskssou (240 m asl, 8 km from the coast) for three summer months (July 1, 2007 to September 30, 2007). Dew water was collected using standard passive dew condensers and fog water by utilizing planar fog collectors. The wind flow was simulated on the rooftop to establish the location of the fog collector. At both sites, dew yields and, to a lesser extent, fog water yields, were found to be significant in comparison to rain events. Mirleft had 178 dew events (48.6% of the year, 18 ± 2 L m−2 cumulated amount) and 20 fog episodes (5.5% of the year, 1.4 L m−2 with uncertainty −0.2/+0.4 L m−2 cumulated amount), corresponding to almost 40% of the yearly rain contribution (31 rain events, 8.5% of the year, 49 ± 7 mm cumulated amount). At Id Ouasskssou there were 50 dew events (7.1 ± 0.3 L m−2, 54.3% frequency), 16 fog events (6.5 L m−2 with uncertainty −0.1/+1.8 L m−2, 17.4% frequency) and six rain events (16 ± 2 mm, 6.5% frequency).