The disastrous consequences of hydrological risks are of paramount importance, hence the need to prevent them and minimize their impacts, if not eliminate them. In this perspective, the study of flood-related risks in the Cavally watershed was carried out. The objective was to analyze the risks related to floods using different approaches. The study was based on the frequency analysis of three series of extreme flows constituted from the daily flows measured at the different hydrometric stations. These series of flows are made up of annual maximum flows, overthreshold flows and maximum flows obtained on the annual series on which were applied the moving averages of daily duration d. After the frequency analysis of these variables, the construction of the QdF curves was carried out. The study showed that flood discharge times are higher at Toulepleu and Feté (4 - 40 days) than at Nékaounié and Tiéouléoula (1 - 10 days). The frequency analysis showed that the Weibull, Gamma, GEV and Gumbel laws are the best laws that fit the different flood flow series. The QdF curves obtained from the different variables show that those obtained with suprathreshold values give more satisfaction compared to the maxan values. These QdF curves describing the intensity of daily flows showed quantiles of flows with return periods from 2 to 100 years, all higher than the average flows observed in the watershed, thus demonstrating a high risk of flooding since even the most frequent floods are likely to generate floods. Compared to the results obtained by applying the reference basin models, the analysis of the QdF curves showed that the Vandenesse model is better in the observable frequency domain as well as in the rare frequency domain.

This study is entitled «Analysis of the rainfall aggressiveness on the soils of the N’Zi watershed. The objective is to analyze the importance of precipitation on soil erosion. To achieve the objective, daily, monthly and annual rainfall data on the N’zi watershed were collected over the period 1960 to 2019. The analysis of rainfall risks was possible for the index of erosivity of Arnoldus and Rango-Arnoldus rainfall, to graphical and spatial representations with R software and ArcGIS software. The results of the analysis of the interannual variability of precipitation show that the temporal aggressiveness generally declined during the 1970s. The rainfall aggressiveness indicates on a monthly scale a weak aggressiveness in general and the strongest would be seasonal at the level of the localities of the basin. It highlights three levels of rainfall aggressiveness on an annual scale: very aggressive aggressiveness (32%), less aggressive (48%) and more or less aggressive aggressiveness (20%), at the basin scale. Five (5) classes were distinguished; excess dominance (41%) qualified as high rainfall aggressiveness, dry period (30%) qualified as low rainfall aggressiveness, a minimum period (18%) qualified as very low rainfall aggressiveness, a maximum period (9%) qualified very high rainfall aggressiveness and a normal period (2%) qualified as average rainfall aggressiveness.

This study aims to assess the evolution of water balance parameters watershed Comoe in a context of climate change. Using the GR2M hydrological model, climate data from the climate model RegCM3 under the A2 emission scenario were simulated to get infiltration, runoff and evaporation and plant transpiration for the periods 1991-2000, 2031-2040 and 2091-2100. Similarly, monthly hydrological and climatic data were used to calibrate the parameters of GR2M hydrological model over the period 1961-1990. The calibration of the hydrological model gave Nash values between 57% to 72%. At validation, Nash criterion varies from 51% to 75%. The results of projection, revealed a decrease in runoff of 18.8% to 34% in 2031-2040 and 40% to 73% in 2091-2100 horizon in different localities. Refills of sheets that are through infiltration could decrease by 7% to 13% in 2031-2040 horizon and 49.3% to 70% in 2091-2100. The decrease in these two consecutive hydrological parameters is, firstly, to falling precipitation of 7.17% and, secondly, an increase in the evaporation and plant transpiration via the temperature increase of 3.6

This study aims to identify the optimal time of planting upland rice in the Center-west of C