Diagnostic of hydrous state of drain in the mid-dry season of kohodio watershed using multispectral images of Landsat generation from 1986 to 2018

This study focuses on the kohodio watershed in north-eastern of Cote d'Ivoire. The objective is to present the seasonal variation of the water status during the wet season and in the mid-dry season, from 1986 to 2018, using remote sensing. This study focuses on the Kohodio watershed in northeastern Cote d'Ivoire. The aim is to present the seasonal variation of the hydrous state of drains from wet season (December-January) to mid-dry season using Landsat multispectral image processing (TM 1986, ETM + 2002 and OLI 2018). The approach combine: (i) the discrimination of wet drains by calculating moisture indices in mid-dry season and color compositions in wet-season; (ii) the automatic extraction of wet units on our composite indices and images; (ii) and the superposition of the global hydrographic network on the extracted layers. The intersection allowed mapping of wet drains in the wet season and in the mid-dry season. The analysis shows that the physical and spatial hydrous state results in the drying of the drains from 1986 to 2018. Total length of wet drains in the basin is 23.80%; 21.7% and 22.4% of its water potential during wet season; and 21.1%; 7.7% and 10.1% in the dry mid-season, respectively in 1986, 2002 and 2018. From the end of the rains until mid-dry season, rate drain drying is 11.2%; 64.6% and 54.8% respectively in 1986, 2002 and 2018. drain drying observed in the mid-dry season was greatly felt from 1986 to 2002, with a percentage equal to -63.70%. This phenomenon is the consequence of climate change and the construction of dams of reservoirs in the area.