Study of Impact of Climate Change on Surface Water Through Hydrological Modeling: Case of Dano Catchment in Burkina-Faso
Ganda, Ngague Hisseine
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Climate change is one of the most complex and sensitive issues at the beginning of the twenty-first century. In Burkina Faso, a Sahel country, the problem of water resources is closely linked to rainfall, which is both low and uncertain. In the last 40 years, rainfall has been steadily declining, with periods of increased drought, especially in the 1970s and 1980s. These events have altered the hydrology of the basins of the zone. The current work applied five regional climate model products and two conceptual hydrological simulation models to assess climate change impact on water resources in the Dano catchment. The projected climate change signal for the catchment was analyzed through the comparison between two future periods (P1: 2021-2050 & P2: 2071-2100) and the historical period (1976-2005). The impact of the detected climate change signal on surface water was then assessed using hydrological models HBV-light and GR4J that were successfully validated (NSE= 0.85 and R2=0.88 for HBV-light and GR4J NSE = 0.85 and R2 = 0.83 respectively) The results indicate for climate change that: (i) the temperature will increase from 0.1 to 2.8 ° C for the five regional climate products; (ii) precipitation will increase by 20.92% on P1 and 3.28% on P2 according to the ESM-CCLM model, by 1.42% on P1 according to the HadGEM2-RCA model and by 0.51% on P1 according to the ESM-REMO model while the models HadGEM2-CCLM, HadGEM2-RCA, ESM-RCA and ESM-REMO instead project respective decreases of P1 = -2.71% and P2 = -3.07%; P2 = -2.16%; P1 = -8.35% and P2 = -2.89% and P2 = 17.12%. The projected discharge change signals are consistent with the projected precipitation change signal: (i) a decrease of -12.63 mm on P1 and -16.29 mm on P2 for the HadGEM2-CCLM model, - 11.67 mm for the HadGEM2 model -RCA, and for the ESM-RCA and ESM-REMO models a respective decrease of -1.69 mm on P1 and -34.60 mm on P2; -23.93 on P1 and -47.48 mm on P2, and an increase for the ESM-CCLM models (P1 = 63.56 mm and P2 = 3.60 mm) and HadGEM2-RCA (P1 = 6.16 mm). These trends are similar for both hydrological models, but the magnitude of the change is higher with HBV-light than with GR4J. These results suggest for future surface water resources management under climate change in the catchment to consider both discharge increase and decrease as the study shows that both trends are plausible. Under increased discharge conditions flood and erosion risk will increase, while water shortage due to flow cessation will be more prominent under decreasing discharge conditions. Therefore, adaptation measures to cope with climate change impact on surface water resources in the Dano catchment should be tailored considering both directions; they should include soil and water conservation technics that are valid under both projected discharge trends.