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Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/hess-2017-591
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
25 Oct 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Hydrology and Earth System Sciences (HESS).
Scenario-based impacts of land use and climate changes on the hydrology of a lowland rainforest catchment in Ghana, West Africa
Michael S. Aduah1, Graham P. W. Jewitt2, and Michele L. W. Toucher2,3 1Department of Geomatic Engineering, University of Mines and Technology, Tarkwa, Box 237, Ghana
2Centre for Water Resources Research, University of KwaZulu-Natal, PBAG x01, 3209, Scottsville, Pietermaritzburg, South Africa
3South African Environmental Observation Network, Grasslands-Wetlands-Forests Node, PO Box 13053, Cascades, 3202, Pietermaritzburg, South Africa
Abstract. This study analysed the separate and the combined impacts of climate and land use changes on hydrology on the Bonsa catchment in Ghana, West Africa, using the ACRU hydrological model. The study used five RCP8.5 climate change scenarios (wet, 25th percentile, 75th percentile, dry and a multi-model median of nine GCMs) from the CMIP5 AR5 models for near (2020–2039) and far (2060–2079) future time slices. Change factors were used to downscale the GCM scenarios to the local scale, using observed climate data for the control period of 1990 to 2009. The land use of 1991 and 2011 were used as the baseline and current land use as well as three future land use scenarios (BAU, EG, EGR) for two time slices (2030 and 2070) were used. The study showed that under all separate climate change scenarios, overall flows reduced, but under combined climate and land use changes, streamflows increased. Under the combined scenarios, streamflow responses due to the different future land use scenarios were not substantially different. Also, land use is the dominant controlling factor in streamflow changes in the Bonsa catchment under a dry climate change, but under a wet climate change, climate controls streamflow changes. The spatial variability of catchment streamflow changes under combined land use and climate changes were greater than the spatial variability of streamflow changes under climate change. The range of plausible future streamflows changes derived in this study provides natural resources and environmental managers of the Bonsa catchment, the first ever and the most current information to develop suitable adaptation and mitigation strategies, to prepare adequately for climate and land use changes.

Citation: Aduah, M. S., Jewitt, G. P. W., and Toucher, M. L. W.: Scenario-based impacts of land use and climate changes on the hydrology of a lowland rainforest catchment in Ghana, West Africa, Hydrol. Earth Syst. Sci. Discuss., https://doi.org/10.5194/hess-2017-591, in review, 2017.
Michael S. Aduah et al.
Michael S. Aduah et al.
Michael S. Aduah et al.

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Short summary
The study provides a first stage contextualized estimation of the potential impacts of combined land use and climate changes on the rainforest part of the West African region, using a representative study area in south western Ghana. The study shows clearly that if the rainfall reduce drastically, changes in streamflow will be controlled by land use changes, but if rainfall increases, streamflows will be controlled by climate. Data and adaptive catchment management is needed for the region.
The study provides a first stage contextualized estimation of the potential impacts of combined...
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