Infrastructure built to protect cities from flooding can increase economic damages elsewhere.
Image credit: Michelle A. Hummel.
Edited by Peter H. Gleick, Pacific Institute for Studies in Development, Environment, and Security, Oakland, CA, and approved November 1, 2016 (received for review August 27, 2016)
Significance
The notion that sudden impacts on shared international waters can be detected and quantified, even in a war zone, is important to scientists and policy makers, who have been stifled in the past by inaccessibility to such regions and the consequent inability to collect relevant data. Our study uses satellite imagery of war-torn Syria, showing how conflict and migration caused sudden reductions in Syrian agricultural land use and water use. An unexpected effect of the conflict was increased flow in the Yarmouk River to Jordan, which nonetheless remains one of the world’s most water-poor nations. The study illustrates that conflict and human displacement can significantly alter a basin’s water balance with dramatic effects on the transboundary partitioning of water resources.
Abstract
Since 2013, hundreds of thousands of refugees have migrated southward to Jordan to escape the Syrian civil war that began in mid-2011. Evaluating impacts of conflict and migration on land use and transboundary water resources in an active war zone remains a challenge. However, spatial and statistical analyses of satellite imagery for the recent period of Syrian refugee mass migration provide evidence of rapid changes in land use, water use, and water management in the Yarmouk–Jordan river watershed shared by Syria, Jordan, and Israel. Conflict and consequent migration caused ∼50% decreases in both irrigated agriculture in Syria and retention of winter rainfall in Syrian dams, which gave rise to unexpected additional stream flow to downstream Jordan during the refugee migration period. Comparing premigration and postmigration periods, Syrian abandonment of irrigated agriculture accounts for half of the stream flow increase, with the other half attributable to recovery from a severe drought. Despite this increase, the Yarmouk River flow into Jordan is still substantially below the volume that was expected by Jordan under the 1953, 1987, and 2001 bilateral agreements with Syria.
Footnotes
- ↵1To whom correspondence should be addressed. Email: marc.muller{at}nd.edu.
Author contributions: M.F.M., J.Y., and S.M.G. designed research; M.F.M. performed research; M.F.M. and N.A. analyzed data; and M.F.M., J.Y., S.M.G., and A.T. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1614342113/-/DCSupplemental.
Impact of the Syrian conflict on water resources
Article Classifications
- Physical Sciences
- Sustainability Science
- Social Sciences
- Environmental Sciences
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- Article
- Abstract
- Water Resources Assessment in a War Zone
- Effect of Migration on Land Use
- Effect of Migration on Reservoir Levels
- Attribution of Transboundary Flow Increases
- Summary and Implications
- Materials and Methods
- 1. Bias Correction of PERSIANN Precipitation
- 2. Bias Correction and Classification of NDVI Images
- 3. Validation of Remote Sensing Analysis
- 4. Cloud Detection and Classification of MNDWI Images
- 5. Correction of Landsat ETM+ Image-Striping Defect
- 6. Construction of Reservoir Filling curves
- 7. Sensitivity to Systematic Land Use Classification Error
- 8. Wet-Season (Winter) Water Balance Equation
- 9. Panel Analysis of the Effect of Refugee Migration on Irrigated Land
- 10. Crop Water Use from Stored Surface Water
- 11. Components of Stream Flow Increase
- 12. Components of Agricultural Water Use
- Acknowledgments
- Footnotes
- References
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