Advances in Geosciences www.adv-geosci.net 1680-7340 1680-7359 21 Transdisciplinary concepts and modelling strategies for the assessment of complex environmental systems 2009 10.5194/adgeo-21-57-2009 http://www.adv-geosci.net/21/57/2009/ http://www.adv-geosci.net/21/57/2009/adgeo-21-57-2009.html http://www.adv-geosci.net/21/57/2009/adgeo-21-57-2009.pdf 57 62 2009-08-11 The Volta Basin Water Allocation System: assessing the impact of small-scale reservoir development on the water resources of the Volta basin, West Africa C. Leemhuis leemhuis@uni-bonn.de G. Jung R. Kasei J. Liebe Center for Development Research, Walter-Flex-Strasse 3, Bonn, Germany Institute for Meteorology and Climate Research, Karlsruhe Institute of Technology, Garmisch-Partenkirchen, Germany now at: C.N.R. Institute for Atmospheric Pollution, Division of Rende, Italy In the Volta Basin, infrastructure watershed development with respect to the impact of climate conditions is hotly debated due to the lack of adequate tools to model the consequences of such development. There is an ongoing debate on the impact of further development of small and medium scale reservoirs on the water level of Lake Volta, which is essential for hydropower generation at the Akosombo power plant. The GLOWA Volta Project (GVP) has developed a Volta Basin Water Allocation System (VB-WAS), a decision support tool that allows assessing the impact of infrastructure development in the basin on the availability of current and future water resources, given the current or future climate conditions. The simulated historic and future discharge time series of the joint climate-hydrological modeling approach (MM5/WaSiM-ETH) serve as input data for a river basin management model (MIKE BASIN). MIKE BASIN uses a network approach, and allows fast simulations of water allocation and of the consequences of different development scenarios on the available water resources. The impact of the expansion of small and medium scale reservoirs on the stored volume of Lake Volta has been quantified and assessed in comparison with the impact of climate variability on the water resources of the basin. Andreini, M., van de Giesen, N., van Edig, A., Fosu, M., and Andah, W.: Volta Basin Water Balance, ZEF-Discussion Paper on Development Policy, Number 21, 2000. Annor, F. A., van de Giesen N., Liebe, J., van de Zaag, P., Tilmant, A., and Odai, S. N.: Delineation of small reservoirs using radar imagery in a semi-arid environment: A case study in the Upper East Region of Ghana, Phys. Chem. Earth, 34(4–5), 309–315, 2009. Cecchi, P.: Towards an Atlas of Lakes and Reservoirs in Burkina Faso, SRP Tool Kit Working Paper, 2008. Danish Institute of Hydrology: MIKE BASIN. A versatile decision support tool for integrated water resources management and planning, DHI Water and Environment, Denmark, 2003. Forkour, G.: Modelling the optimum areas for constructing small reservoirs in Ghana, Msc. Thesis, University College London (UCL), 18–40, 2006. International Institute for Water and Environnemental Engineering: Retenues d'eau au Burkina Faso, Version 2.0, 2006. IPPC: Climate Change 2001: The Scientific Basis, 2001. Jung, G.: Regional Climate Change and the Impact on Hydrology in the Volta Basin of West Africa, Institut für Meteorologie und Klimaforschung (IMK-IFU), 41–90, 2006. Jung, G. and Kunstmann, H.: High resolution regional climate modeling for the Volta region of West Africa, Journal of Geophysical Research, 112, D23108, doi:10.1029/2006JD007951, 2007. Kunstmann, H. and Jung, G.: Impact of regional climate change on water availability in the Volta Basin of West Africa, in: IAHS Publication No. 295 "Regional Hydrological Impact of Climate variability and Change", 75–85, 2005. Liebe, J., van de Giesen, N., and Andreini, M.: Estimation of small reservoir storage capacities in a semi-arid environment – A case study in the Upper East Region of Ghana, Phys. Chem. Earth, 30(6–7), 448–454, 2005. McKnee, T. B., Doesken, N. J., and Kleist, J.: The relationship of drought frequency and duration to time scales, 8th Conference on Applied Climatology, 179–184, Anaheim, California, USA, 1993. Taylor, J. C., van de Giesen, N., and Steenhuis, T.: West Africa: Volta discharge data quality assessment and use, J. Am. Water Resour. Assoc., 42(4), 1113–1126, 2006. United Nations Development Program: Human Development Report 2007/2008, http://hdr.undp.org/en/media/HDR_20072008_EN_Complete.pdf, 2007. Van de Giesen, N., Andreini, M., van Edig, A., and Vlek, P.: Competition for water resources in the Volta basin, IAHS Publ. no. 268, 2001.