Impact of the Syrian Refugee Crisis on Land Use and Transboundary Freshwater Resources

Impact of the Syrian refugee crisis on land use and transboundary freshwater resources Marc François Müllera,b,1, Jim Yoona, Steven M. Gorelicka, Nicolas Avissec, and Amaury Tilmantc aDepartment of Earth System Science, Stanford University, Stanford, CA 94305; bDepartment of Civil & Environmental Engineering & Earth Sciences, University of Notre Dame, Notre Dame, IN 46556; and cDepartment of Civil and Water Engineering, Université Laval, Quebec, QC, Canada G1V 0A6 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) Since 2013, hundreds of thousands of refugees have migrated operational in 2007. The reservoir captures much of the Yarmouk southward to Jordan to escape the Syrian civil war that began in flow, serving as a significant water storage facility for Jordan. In the mid-2011. Evaluating impacts of conflict and migration on land use past several decades, the Yarmouk watershed upstream of the Al- and transboundary water resources in an active war zone remains Wehda dam has been extensively exploited by Syria with the con- a challenge. However, spatial and statistical analyses of satellite struction of 21 dams to enable intensive agricultural irrigation, imagery for the recent period of Syrian refugee mass migration resulting in substantial flow decreases to downstream Jordan and provide evidence of rapid changes in land use, water use, and water Israel (Fig. S1D). After 2012, inflow records at Al-Wehda reservoir management in the Yarmouk–Jordan river watershed shared by Syria, show a sudden reversal in this declining flow trend, an unexpected Jordan, and Israel. Conflict and consequent migration caused ∼50% increase as rainfall declined between 2012 and 2014 (Fig. 1). How- decreases in both irrigated agriculture in Syria and retention of winter ever, there is a clear correspondence between the flow increase and the number of refugees migrating out of the Syrian side of the basin rainfall in Syrian dams, which gave rise to unexpected additional (Fig. 1). This correspondence suggests a potential relationship be- stream flow to downstream Jordan during the refugee migration pe- tween civil conflict, land use, and water consumption in Syria, with riod. Comparing premigration and postmigration periods, Syrian aban- consequent changes to the hydrological response. donment of irrigated agriculture accounts for half of the stream flow This study explores the impact of armed conflict and conse- increase, with the other half attributable to recovery from a severe quent Syrian refugee migration on land use and freshwater re- SCIENCE drought. Despite this increase, the Yarmouk River flow into Jordan is sources. We show that the abrupt increase in transboundary river SUSTAINABILITY still substantially below the volume that was expected by Jordan un- flow is a consequence of rapid upstream changes stemming from der the 1953, 1987, and 2001 bilateral agreements with Syria. the Syrian civil war. Results indicate that the Syrian conflict and refugee crisis caused a substantial decline in agricultural land use remote sensing | Landsat | reservoir | conflict | irrigation and irrigation water use, and a significant alteration in the management of the Syrian stored water supply system, which ulti- isputes over scarce water resources rarely escalate into full- mately resulted in increased flow to downstream Jordan. Dblown wars (1–4), but the impact of drought on water re- SCIENCES sources and agricultural land use is severely impacting the Middle Water Resources Assessment in a War Zone ENVIRONMENTAL East. The effect is most apparent in the current Syrian civil war, Reliable land use and hydrological data are essential to investigate where poor governance and overreliance on intensive irrigation the changes in Syria on transboundary river flow to Jordan, but diminished the country’s ability to cope with a severe drought (5, 6). collecting data in an active war zone is a major challenge. Satel- That drought, which hit the Middle East between 2006 and 2008 lite data are increasingly exploited during situations requiring rapid collection of data in environments that are difficult to ac- (6–8), had a detrimental effect on freshwater resources with con- cess, such as for disaster response and emergency mapping (13). sequent human impacts. The Syrian civil war was sparked by riots in ’ Here, we use satellite imagery to investigate causal relations between the southern city of Dara a (5), located in the Yarmouk River basin, changes in land use and water resources during an armed conflict. a subbasin of the Jordan River watershed, which is shared with Jordan and Israel. Poor crop yieldsinSyrialedtothecollapseof Significance the agricultural sector and large-scale migration to urban areas, contributing to economic hardship, political instability, and ultimately, armed conflict (5). The ensuing war caused a massive migration The notion that sudden impacts on shared international waters of Syrian refugees to neighboring countries, largely in 2013. The can be detected and quantified, even in a war zone, is impor- combined effect of conflict-related power outages and migra- tant to scientists and policy makers, who have been stifled in tion out of southern Syria is clearly visible in night-light images the past by inaccessibility to such regions and the consequent (Fig. 1C) that reflect population changes in the small cities and inability to collect relevant data. Our study uses satellite im- villages in the area (9). Data from the United Nations High Com- agery of war-torn Syria, showing how conflict and migration mission on Refugees (10) suggests that in excess of 369,000 people caused sudden reductions in Syrian agricultural land use and were driven out of the Syrian portion of the Yarmouk basin, an water use. An unexpected effect of the conflict was increased estimate that excludes the large number of unregistered refugees. flow in the Yarmouk River to Jordan, which nonetheless re- ’ This migration put major stress on Jordan’s infrastructure, mains one of the world s most water-poor nations. The study including its water resources (11), a heavy burden for a country illustrates that conflict and human displacement can signifi- ranked among the most water-scarce in the world even before the cantly alter a basin’s water balance with dramatic effects on refugee influx (12). However, the refugee crisis also coincided with the transboundary partitioning of water resources. an unexpected, rapid increase in flow in the Yarmouk River from Syria to the Al-Wehda reservoir on the Syria–Jordan border (Fig. Author contributions: M.F.M., J.Y., and S.M.G. designed research; M.F.M. performed re- 1), which feeds Jordan’s water supply system. The Yarmouk River search; M.F.M. and N.A. analyzed data; and M.F.M., J.Y., S.M.G., and A.T. wrote the paper. is the primary tributary to the lower Jordan River and a strategic The authors declare no conflict of interest. transboundary freshwater resource. The river has historically This article is a PNAS Direct Submission. been the largest natural surface water source available to Jordan, 1To whom correspondence should be addressed. Email: [email protected]. providing a significant portion of the country’s surface water sup- This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10. ply. The Al-Wehda dam, along the Jordan–Syria border, became 1073/pnas.1614342113/-/DCSupplemental. www.pnas.org/cgi/doi/10.1073/pnas.1614342113 PNAS Early Edition | 1of6 Downloaded by guest on September 25, 2021 Rainfall cropland for those areas with high NDVI values during summer A B [mm/yr] Damascus 40 yr 300 months (June to September) when precipitation is negligible. We Mean SYRIA 150 further distinguished summer-irrigated crops from evergreen vegetation by evaluating the difference between median cloud- 0 Al Wehda Daraa free NDVI values in the spring (January to May) and summer, Dam 50 [MCM/yr] bias-correcting to account for temporal variation in NDVI due to Wet Season Dry Season changing soil and atmospheric conditions (Materials and Methods). 25 In Fig. 2, we generated maps of irrigated crop areas for the Amman 0 Jordanian and Syrian portions of the Yarmouk basin between Syrian Refugees* JORDAN 350k 2000 and 2015 (see Fig. S2 for all years and Table S1 for confusion 175k matrices). Irrigated areas increased in both countries between 100 km 2000 and 2006, followed by an abrupt drop during the following 0 years, which corresponds to a regional drought. In Syria, irrigated C 2007 2009 2011 2013 2015 2011 2012 2013 2014 2015 area declined considerably after 2012, coinciding with the flight of Syrian refugees (Figs. 1B and 2 A and B). Notably, the post-2012 drop was much greater in Syria than in Jordan, suggesting that conflict and the flight of refugees caused a major reduction in farming and associated reduction in irrigation water use in Syria. Fig. 1. Yarmouk river flow increase coincides with refugee migration. (A)Mapof Irrigation in Jordan remained unaffected by the influx of refugees, the Yarmouk basin upstream of the Al-Wehda dam, with the Syrian and Jordanian who settled predominantly in camps and cities outside of the parts of the basin (red and green), and the Al-Wehda dam, where stream flow is Yarmouk basin. Using temporal changes in irrigated area in measured. (B) Time series of annual precipitation spatially averaged over the Jordan as a counterfactual scenario, results show a statistically Yarmouk basin (Top, with long-term average represented as a dashed line), annual significant [90% confidence interval (CI)] 47% decrease in irrigated discharge volumes measured at Al-Wehda disaggregated by wet (October to May) land in southern Syria caused by the refugee crisis that started in anddry(JunetoSeptember) seasons (Middle), and the cumulative number of 2013 (Table 1, column 1; interaction coefficient). This effect re- registered refugees from the Syrian part of the basin (Bottom).

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