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Abstract. The aim of the study was to test the applicability of a physically-based model to simulate the hydrological processes in a headwater catchment in Benin. Field investigations in the catchment have shown that lateral processes such as surface runoff and interflow are most important. Therefore, the 1-D SVAT-model SIMULAT was modified to a semi-distributed hillslope version (SIMULAT-H). Based on a good database, the model was evaluated in a multi-criteria validation using discharge, discharge components and soil moisture data. For the validation of discharge, good results were achieved for dry and wet years. The main differences were observable in the beginning of the rainy season. A comparison of the discharge components determined by hydro-chemical measurements with the simulation revealed that the model simulated the ratio of groundwater fluxes and fast runoff components correctly. For the validation of the discharge components of single events, larger differences were observable, which was partly caused by uncertainties in the precipitation data. The representation of the soil moisture dynamics by the model was good for the top soil layer. For deeper soil horizons, which are characterized by higher gravel content, the differences between simulated and measured soil moisture were larger.A good agreement of simulation results and field investigations was achieved for the runoff generation processes. Interflow is the predominant process on the upper and the middle slopes, while at the bottom of the hillslope groundwater recharge and -during the rainy season -saturated overland flow are important processes.

Abstract. This study evaluates climate change impacts on water resources using an ensemble of six regional climate models (RCMs)–global climate models (GCMs) in the Dano catchment (Burkina Faso). The applied climate datasets were performed in the framework of the COordinated Regional climate Downscaling Experiment (CORDEX-Africa) project.After evaluation of the historical runs of the climate models' ensemble, a statistical bias correction (empirical quantile mapping) was applied to daily precipitation. Temperature and bias corrected precipitation data from the ensemble of RCMs–GCMs was then used as input for the Water flow and balance Simulation Model (WaSiM) to simulate water balance components.The mean hydrological and climate variables for two periods (1971–2000 and 2021–2050) were compared to assess the potential impact of climate change on water resources up to the middle of the 21st century under two greenhouse gas concentration scenarios, the Representative Concentration Pathways (RCPs) 4.5 and 8.5. The results indicate (i) a clear signal of temperature increase of about 0.1 to 2.6 °C for all members of the RCM–GCM ensemble; (ii) high uncertainty about how the catchment precipitation will evolve over the period 2021–2050; (iii) the applied bias correction method only affected the magnitude of the climate change signal; (iv) individual climate models results lead to opposite discharge change signals; and (v) the results for the RCM–GCM ensemble are too uncertain to give any clear direction for future hydrological development. Therefore, potential increase and decrease in future discharge have to be considered in climate change adaptation strategies in the catchment. The results further underline on the one hand the need for a larger ensemble of projections to properly estimate the impacts of climate change on water resources in the catchment and on the other hand the high uncertainty associated with climate projections for the West African region. A water-energy budget analysis provides further insight into the behavior of the catchment.

This paper assesses the current use and constraints on the use of inland valleys in central Benin are assessed to analyse their agro-potential. The methodology applied in this study is comprised of a survey of local authorities and inland valley users conducted with standardised questionnaires and the mapping of inland valley surfaces with GPS. The questionnaire contains questions to socioeconomic aspects such as access to an inland valley, land tenure, current use, use constraints as well as questions to physical properties such as soil quality. In addition to the assessment of the inland valley surface area, this approach enabled a detailed socioeconomic and rough physical characterization of all detected inland valleys. In total, 817 inland valleys were surveyed in this study. The local population currently uses sixty-seven percent of the valleys, primarily for crop cultivation. In most cases, only a small part of each surveyed inland valley is used. The intensity of exploitation varies across communes and across seasons. Especially in the more densely populated communes of Djougou and Parakou, where the upland soils are often degraded and arable land has become scarce in recent years, the use of inland valleys is greater than in less populated communes. This exploitation occurs primarily during the rainy season, and only a few farmers cultivate crops during the dry season. This study revealed high unused agro-potential in the inland valleys of central Benin. The main reason why inland valleys in the study area currently remain unexploited is a lack of experience in cultivating wetland. In fact, for more than 60% of the unused inland valleys, the local farmers claim to have no knowledge of which crops are adapted to seasonally waterlogged and swampy land or how to cultivate such crops. Due to climate change and population growth, the agricultural use of inland valleys in this region could become more important in the future. To ensure effective use, farmers should be supported by the regional agricultural organisation CeRPA (Centres Régionaux pour la Promotion Agricol) or development organisations to improve the knowledge of cultivation methods and inland valley management. Zusammenfassung: In diesem Artikel werden die aktuelle Nutzung und die Probleme der Nutzung von �lachmuldent�-In diesem Artikel werden die aktuelle Nutzung und die Probleme der Nutzung von �lachmuldent�lern (inland valleys) in Zentralbenin basierend auf einer standardisierten Befragung der lokalen Bevölkerung und einer GPS-Kartierung analysiert. Der �ragebogen enth�lt sowohl �ragen zu sozio-ökonomischen Aspekten wie Zugang zum inland valley, Landrechten, aktuelle Nutzung, Probleme der Nutzung etc. als auch �ragen zu physischen Eigenschaften wie z.B. Bodenqualit�t. Mit diesem Ansatz konnten neben der reinen Erfassung der inland valley �l�che auch eine umfassende sozioökonomische und eine grobe physische Charakterisierung aller erfassten inland valleys erfolgen. Insgesamt wurden 817 inland valleys in dieser Studie untersucht. 67% dieser �euch...