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ABSTRACT
Reliable estimates of sediment fluxes into rivers provide valuable information for current and future water resource development and management. In this study, empirical equations relating discharge to suspended sediment loads were developed for the three major tributaries (Black Volta, White Volta, and Oti) of the Volta Lake. The empirical equations were fed with projected future river discharges for the three tributaries, to estimate the suspended sediment fluxes into the Volta Lake for the future (2051–2080) relative to a baseline period (2014–2016). The Soil and Water Assessment Tool (SWAT) was used to model the projected discharges. The SWAT model was driven by downscaled climate projections from two regional climate models (RCA4 and RACMO22 T) forced by two emission scenarios (RCP 4.5 and RCP 8.5) from the IPCC Fifth Assessment. Compared to the baseline, the estimated future sediment fluxes show average increments of about 19% and 28%, respectively under RCP 4.5 and RCP 8.5. This has negative consequences as less water is stored for hydropower generation and the lake water becomes more turbid, which inhibits zooplankton and fishery production. The result underscores the need to improve the management of the Lake's watershed by ensuring proper landcover/use planning, afforestation and enforcing regulations on land degradation and general environmental conservation.
Acknowledgement
This study was funded by the ‘Effects of Climate Change on Volta Lake Resources (VOLTRES)’ project at the Water Research Institute of the Council for Scientific and Industrial Research, with funding from the Danish Foreign Ministry via the DANIDA Fellowship Centre. The views expressed in this paper do not reflect those of the CSIR-WRI and DANIDA.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Author contributions
All Authors contributed significantly to the successful completion of this article. MOO: material preparation, data acquisition and analyses, and report writing. EO: data acquisition and analyses, and report writing GKA, CAS and RA: supervised material preparation and data acquisition, reviewed data analysis and report for publication.
Data availability
The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.
Additional information
Notes on contributors
Emmanuel Obuobie
Emmanuel Obuobie is a professional engineer and senior research scientist at the Water Research Institute - Council for Scientific and Industrial Research, Accra, Ghana. He holds a PhD in natural science from the University of Bonn, Germany, a master of science from Soil and Water Engineering from Wageningen University, Netherlands and a bachelor of science from Agricultural Engineering from Kwame Nkrumah University of Science and Technology, Ghana. His past employment included Irrigation Engineer/Research Officer at the International Water Management Institute and a junior researcher at the Centre for Development Studies at the University of Bonn. His research interests include climate downscaling, hydrological modelling, integrated water system analysis, food risk assessment and climate change adaptation. He has several peer-review publication papers in reputable journals to his credit.
Mark Osei-Owusu
Mark Osei-Owusu is an assistant research scientist at the Water Research Institute of the Council for Scientific and Industrial Research. He is a member of the Research Scientist Association (RSA) of Ghana and currently pursuing a PhD in water resources engineering and management at the Kwame Nkrumah University of Science and Technology, Kumasi, Ghana. He has a master of science in water resources engineering and management (2017) from the Kwame Nkrumah University of Science and Technology, Kumasi, Ghana, a bachelor of science in physics (2013) from the University Cape Coast, Ghana and a diploma in basic education (2008) from the Peki College of Education, Ghana. He has served as project staff to Water Infrastructure Solutions from Ecosystem Services Underpinning Climate Resilient Policies and Program and FutureDAMS project in 2017 and 2018, respectively. His research interest and expertise in climate downscaling and hydrological modelling.
Geophrey Kwame Anornu
Geophrey Kwame Anornu is an associate professor who lectures at the civil engineering department at the Kwame Nkrumah University of Science and Technology, Kumasi, Ghana. He holds a PhD in water resources engineering from Belarus Polytechnic Academy, Minsk, Belarus and a master of science in hydraulic engineering from Belarusian Agricultural Academy, Gorki, Belarus. His area of specialization is in water resources and hydraulic engineering. His research area of interest lies with groundwater hydrology, drainage systems, hydraulics, irrigation and drainage. He has several peer-reviewed journal publications to his credit.
Collins Asante-Sasu
Collins Asante-Sasu obtained his master's degree in water resources engineering and management (2016) at the Kwame Nkrumah University of Science and Technology, Ghana and is currently a PhD holder in engineering science from Washington State University, USA. His experience and expertise are in hydrology and hydrogeology. His research interest lies in the areas of evaluating trends and vulnerabilities in groundwater aquifers, application of GRACE satellites to study groundwater storage changes in a complex regional aquifer system, evaluating modelled soil moisture, the use of groundwater resources as a drought mitigation tool and surface water and groundwater sampling and analysis and ArcGIS and analytical software tools.
Ruby Asmah
Ruby Asmah is a principal research scientist with the Fisheries and Aquaculture Division and the deputy director of the Water Research Institute of the Council for Scientific and Industrial Research (CSIR), Ghana. She holds a PhD in aquaculture, a master of science degree in ecological and marine management and a bachelor of science in chemistry. She has vast experience in aquaculture development, water quality management, general farm practices, environmental monitoring and impact assessments, ecological studies and water resources management. She is an external examiner and a reviewer for international peer-reviewed journals, supervises both master's and doctoral levels at various Ghanaian Universities and is a consultant to international mining companies in Ghana. She has several peer-reviewed journal publications, book chapters and conference papers to her credit.