Assessing the Impact of Rainfall Variability on Lake Ono by Using the Supervised Classification Method
KPAN Oulai Jean-Gautier *
Department of Geosciences, Péléféro Gon Coulibaly University of Korhogo, P.O. Box 1328 Korhogo, Côte d'Ivoire.
DIOMANDÉ Métangbo
Department of Geosciences, Péléféro Gon Coulibaly University of Korhogo, P.O. Box 1328 Korhogo, Côte d'Ivoire and Swiss Center for Scientific Research in Côte d'Ivoire, Côte d'Ivoire.
KOFFI Antoine
Department of Geosciences, Péléféro Gon Coulibaly University of Korhogo, P.O. Box 1328 Korhogo, Côte d'Ivoire.
OGA Yéï Marie Solange
Félix Houphouët-Boigny University of Cocody-Abidjan, Côte d'Ivoire.
*Author to whom correspondence should be addressed.
Abstract
The effects of climate change on water resources result from a combination of several factors, including reduced precipitation, decreased runoff, increased evapotranspiration, and decreased groundwater recharge. This study highlights the hydrological impacts of climate variability in southeastern Côte d'Ivoire, particularly in the Lake ONO area. The results obtained using the second-order Hanning method show a period of excess rainfall from 1960 to 1983 (12.64 to 15.15%) and a period of rainfall deficit from 1984 to 2014 (-11.72 to -6.75%) in the region. Supervised classification of TM+ (1986) and ETM+ (2000 and 2016) satellite images of scene 195-056, which was validated by accuracy indices exceeding 98%, shows a reduction in size and eutrophication of Lake Ono in 2000 and 2016, respectively. Its surface area has been reduced by 25%, from 7 km² in 1986 to 5.24 km² in 2016. It also reveals the absence of the “swamp area” class and an increase in “bare soil” areas on the 2000 and 2016 images.
Keywords: Climate variability, satellite images, supervised classification, Lake ONO, Ivory Coast