Nkiaka, E., Bryant, R.G. orcid.org/0000-0001-7943-4781, Dembélé, M. et al. (3 more authors) (2024) Quantifying the effects of climate and environmental changes on evapotranspiration variability in the Sahel. Journal of Hydrology, 642. 131874. ISSN 0022-1694
Abstract
Whilst considerable research has been carried out to understand the effects of reforestation on evapotranspiration (ET), such studies are generally absent in the Sahel even though the region is currently undergoing extensive reforestation to halt desertification and land degradation. The objective of this study is to identify and quantify the dominant climatic and environmental factors influencing ET variability in the Sahel. However, achieving this goal in the Sahel is hindered by a lack of in situ monitoring data. To overcome this challenge, this study adopts geospatial datasets along with analytical methods to assess the climatic and environmental factors affecting ET in 45 watersheds in the Sahel over a period of four decades (1982–2021). Analyses show significant increasing trends in annual ET in more than 90% of the watersheds. Precipitation and mean temperature show significant increasing trends in all watersheds while windspeed, vapour pressure, solar radiation, specific humidity, and atmospheric evaporative demand show mixed results with both increasing and decreasing trends in different watersheds. Environmental variables including soil moisture, and vegetation cover measured using the normalised difference vegetative index (NDVI) also show consistent increasing trends in all watersheds. Statistical analyses further show that climatic and environmental factors contribute about 80% of ET variance. The relative contribution of climatic variables on ET variance is 75.11% while that of environmental variables is 24.71%. This suggests that climatic factors have a higher influence on ET variability than environmental factors. Analyses using the double logarithm elasticity model show that vapour pressure has the highest positive elasticity coefficient (2.58) on ET while net radiation has the highest negative elasticity coefficient (−9.58). This is the first study to cover the whole Sahelian belt from west to east and the results may be crucial for adopting climate-smart reforestation policies, enhance regional water management and improve our knowledge of vegetation-hydrology-climate interactions in the Sahel.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2024 Elsevier B.V. The Authors. Except as otherwise noted, this author-accepted version of a journal article published in Journal of Hydrology is made available via the University of Sheffield Research Publications and Copyright Policy under the terms of the Creative Commons Attribution 4.0 International License (CC-BY 4.0), which permits unrestricted use, distribution and reproduction in any medium, provided the original work is properly cited. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ |
Keywords: | Analytical methods; Elasticity concept; Partial correlation coefficient; Least square and double logarithm elasticity models; Great green wall initiative; NDVI |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Social Sciences (Sheffield) > Department of Geography (Sheffield) |
Funding Information: | Funder Grant number LEVERHULME TRUST (THE) ECF-2020-097 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 22 Aug 2024 11:14 |
Last Modified: | 25 Feb 2025 10:40 |
Status: | Published |
Publisher: | Elsevier BV |
Refereed: | Yes |
Identification Number: | 10.1016/j.jhydrol.2024.131874 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:216355 |