The water resources of the Volta watershed in Côte d'Ivoire are often destined for human consumption and the development of agro-pastoral or industrial activities. This study aims to characterize climate variability and its consequences and to analyze the dynamics of land-use on the water resources of this basin, from hydrological models and GIS. Since the rainfall decline, observed during the years 1963 to 1970, several periods of drought have been observed and have caused the disappearance of plant species, some water bodies and some areas of groundwater recharge. The determined rainfall during the period 1936 to 2002 is 1102.86mm with only a surplus of 87.30mm of which 5.68% is destined for surface runoff and 2.23% for groundwater recharge. The flow rate of rivers from 1990 to 1993 is 1.39m3.s-1 with a drying up coefficient of 6.95.10-2 j-1 and a mobilized water volume by aquifers of only 0.028km3. These parameters determine a low hydraulic potential of the basin. Dominated by tree savannah or shrubby savannah (81.17%) in 1990, the degradation of the vegetation cover of the basin has had adverse effects on water resources. However, until the year 2000, the regeneration of gallery forest and dense tree savannah (from 8.48% to 16.01%) will favor the reconstitution of some water bodies. Thus, for an effective rehabilitation of the environment, it will be necessary to reinforce the strategic plans for adaptation to climate variability.

The surface water resources in the region of Bonoua are subject to strong anthropogenic pressures created by the development and expansion of agricultural activities and also by the agro-industrial and domestic activities. This impacts the available quantities of these resources that fluctuate throughout the year. Similarly, their quality is thereby also changed. Regarding the quality of these resources how can occur at a given time of year? This concern led in this study to assess the overall quality of surface waters of Bonoua region during the rainy season. It is based on the exploitation of data from a water sampling campaign conducted in July 2014. The data were processed with the Evaluation System of Quality of Waters, referred to as "SEQ-Eau" for determining the overall water quality. The (ACPN) has also been applied to the data for the identification of phenomena causing water pollution. The results show that in general the surface waters in the region are Bonoua of "average quality" to 92.86% and "poor" at 7.14%. The responsible alteration of this deterioration in the quality of surface water is the "acidification" parameter, which contributes to 64%. Alterations "temperature" and "organic and oxidizable materials" expressed as COD and BOD 5 incidentally involved in this deterioration in the respective proportions of 14 % and 22 %. The phenomena causing water pollution is anthropogenic. They are mainly from discharges of domestic and industrial waste water and the use of chemical fertilizers in the plantations. This evaluation of the quality of surface water in the region of Bonoua is a first draft that should be complemented by other studies covering aspects such as pesticides and microbiology for better management.