Enhancement of rainfall and runoff upstream from irrigation location in a climate model of West Africa
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Eltahir_Enhancement of rainfall.pdf
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Author(s)
Im, Eun Soon
Eltahir, Elfatih A. B.
Date Issued
November 2014
Journal
Water Resources Research
Publisher
American Geophysical Union
Citation
Im, Eun-Soon and Eltahir, Elfatih A. B. “Enhancement of Rainfall and Runoff Upstream from Irrigation Location in a Climate Model of West Africa.” Water Resources Research 50, 11 (November 2014): 8651–8674 © 2014 American Geophysical Union
Version
Final published version
Abstract
This study investigates the impact of potential medium-scale irrigation (about 60,000 km²) on the climate of West Africa using the MIT Regional Climate Model. We find that irrigation at this scale induces an atmospheric response similar to that of large-scale irrigation (about 400,000km²) which was considered in our previous theoretical study. While the volume of water needed for large-scale irrigation is about 230–270 km³, the medium-scale irrigation requires about 50 km³, and the annual flow of the Niger river in the relevant section is about 70 km³. The remote response of rainfall distribution to local irrigation exhibits a significant sensitivity to the latitudinal location of irrigation. The nature of this response is such that irrigation from the Niger River around latitude 18°N induces significant increase in rainfall of order 100% in the upstream sources of the Niger River and results in significant increase in runoff of order 50%. This additional runoff can potentially be collected by the river network and delivered back toward the irrigation area. By selecting the location of irrigation carefully, the positive impacts of irrigation on rainfall distribution can be maximized. The approach of using a regional climate model to investigate the impact of location and size of irrigation schemes, explored in this study, may be the first step in incorporating land-atmosphere interactions in the design of location and size of irrigation projects. However, this theoretical approach is still in early stages of development and further research is needed before any practical application in water resources planning.
MIT Department
Singapore-MIT Alliance in Research and Technology (SMART)
Parsons Laboratory for Environmental Science and Engineering (Massachusetts Institute of Technology)
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.1002/2014WR015592
