Understanding the impacts of climate change on water resources is of utmost importance to successful water management and further adaptations strategies. The objective of this paper is to assess the impacts of climate change on river discharge dynamics in Oueme River basin in Benin. To this end, this paper used the distribution based scaling approach to improve usability of regional climate model projections for hydrological climate change impacts studies. Hydrological simulations in B????t????rou and Bonou sub-catchments of the Oueme River were carried out with a lumped conceptual hydrological model. The main contribution of this paper is to use the hydrological model based on the least action principle (HyMoLAP), which is designed to minimize uncertainties related to the rainfall-runoff process and scaling law, for this assessment. The bias correction approach allows reducing the differences between the observed rainfall and the regional climate model (HIRHAM5 and RCA4) rainfall data. Corrected and raw HIRHAM5 and RCA4 rainfall data were compared with the observed rainfall using Mean Absolute Error (MAE) and Root Mean Square error (RMSE). The results of the bias correction show a decrease in the RMSE and MAE of the raw HIRHAM5 and RCA4 rainfall data of approximately 91% to 98% in both catchments. The results of the simulation indicate that the HyMoLAP is suitable for modelling river discharge in the Oueme River basin. For the future projection based on RCP4.5 scenarios, the projected mean annual river discharge by using HIRHAM5 and RCA4 in B????t????rou and Bonou decrease with the magnitude ranging respectively from ?￠????25% to ?￠????39% and ?￠????20% to ?￠????37% in the three time horizons 2020s (2011?￠????2040), 2050s (2041?￠????2070) and 2080s (2071?￠????2100), representing the early, middle and late of 21st century. As regards the future projection based on RCP8.5 scenarios, the projected mean annual river discharge by using HIRHAM5 and RCA4 in B????t????rou and Bonou decrease with the magnitude ranging respectively from ?￠????15% to ?￠????34% and ?￠????18% to ?￠????36% in the three time horizons. The model uncertainties projections indicated that the entire discharge distribution shifted toward more extreme events (such as drought) compared to the baseline period.
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机译：理解气候变化对水资源的影响对于成功的水管理和进一步的适应战略至关重要。本文的目的是评估气候变化对贝宁Oueme流域河流排放动态的影响。为此，本文使用基于分布的缩放方法来提高区域气候模型预测用于水文气候变化影响研究的可用性。用集总的概念水文模型对Oueme河的B？t？rou和Bonou子汇水区进行了水文模拟。本文的主要贡献是使用基于最小作用原理（HyMoLAP）的水文模型进行评估，该模型旨在最小化与降雨径流过程和尺度定律相关的不确定性。偏差校正方法可以减少观测到的降雨与区域气候模型（HIRHAM5和RCA4）降雨数据之间的差异。使用平均绝对误差（MAE）和均方根误差（RMSE）将校正后的原始HIRHAM5和RCA4降雨量数据与观测到的降雨量进行比较。偏差校正的结果表明，两个流域的原始HIRHAM5和RCA4降雨数据的RMSE和MAE下降了大约91％至98％。仿真结果表明，HyMoLAP适用于对Oueme流域的河流流量进行建模。对于基于RCP4.5情景的未来预测，在B ??? t ??? rou和Bonou中使用HIRHAM5和RCA4预测的平均年河流量，幅度分别为??????? 25。在三个时间段2020年代（2011年）（2040年）和2050年代（2041年）中，％分别为39％和20％到37％。 2070年）和2080年代（2071年：2100年），分别代表21世纪初期，中期和晚期。关于基于RCP8.5情景的未来预测，在B ??? t ??? rou和Bonou中使用HIRHAM5和RCA4预测的年平均河流流量随着幅度的变化而降低，范围分别为。在三个时间范围内，分别占15％到34％和18％到36％。模型的不确定性预测表明，与基准期相比，整个流量分布向更极端的事件（如干旱）转移。
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