The water of the Issia reservoir is used to supply drinking water to the local population. Unfortunately, the various anthropogenic pressures in the Lobo watershed threaten the quantity of water flows entering the Issia reservoir. The objective of this study is to assess the impact of the combined actions of anthropization and climate change on the water flows entering the Issia reservoir. The approach implemented was based on the coupling of remote sensing and agro-hydrological modeling with SWAT. The diachronic analysis of Landsat 7 ETM+ (2008 and 2013) and Sentinel-2 (2019) images through the method of supervised classification by maximum likelihood has allowed to discriminate five (05) classes of land use that are: forest, degraded forest, habitat and bare soil, crop and fallow, and water bodies. The overall accuracies obtained for the 2008, 2013 and 2019 classified images are 90%; 92% and 95.33% respectively. The Kappa indices of the confusion matrix for the three classified images are 0.88; 0.9 and 0.94 for 2008, 2013 and 2019 respectively. From 2008 to 2019, dense forest, degraded forest, and crops and fallow had overall regressions of 13.70%, 10.49%, and 1.29% respectively. In addition, bare soil and habitats and water bodies increased by 75.50% and 57.09% respectively. The graphical and statistical criteria of the SWAT model (NS and R2, greater than 0.5) showed good model performance for both calibration and validation. The water balance analysis for the 2050 time horizon indicates that water flows into the reservoir will decrease by 52% compared to current flows. This decrease could constitute a real threat for the population of the Issia locality in the years to come.

The Lobo River reservoir, the main source of drinking water supply for the municipality of Daloa, is facing a deterioration in its quality. This study aims to assess the quality of this resource. The physico-chemical and chemical parameters of this water were determined during the two seasons of the year 2020. The methodological approach consisted firstly of characterizing the water in the reservoir in relation to the WHO guide values; secondly, determining the phenomena that govern the mineralization of this water and, thirdly, calculating the organic pollution index (OPI) and the water quality index (WQI) of the reservoir. The results show that the physico-chemical parameters (T, pH and EC) comply with the WHO guide values. However, the water has a high turbidity, with a very strong colour in all seasons. Phosphate (0.93 mg/L), ammonium (1.48 mg/L), total iron (2.99 mg/L) and manganese (0.66 mg/L) concentrations are high. On the other hand, chlorides, nitrates and nitrites remain low in both seasons. On the other hand, chlorides, nitrates and nitrites remain low in both seasons. Normalized Principal Component Analysis (NPCA) revealed that the mineralization of this water is of natural and anthropogenic origin. The water quality (2.25 to 3.25) and organic pollution (429.73 to 693.31) indices show that the water in the reservoir is unfit for consumption, with moderate pollution in the dry season and heavy pollution in the rainy season.