Rajsekhar Deepthi, Gorelick Steven M
California Department of Water Resources, Sacramento, CA 95814, USA.
Department of Earth System Science, Stanford University, Stanford, CA 94305, USA.
Sci Adv. 2017 Aug 30;3(8):e1700581. doi: 10.1126/sciadv.1700581. eCollection 2017 Aug.
In countries where severe drought is an anticipated effect of climate change and in those that heavily depend on upstream nations for fresh water, the effect of drier conditions and consequent changes in the transboundary streamflow regime induced by anthropogenic interventions and disasters leads to uncertainty in regional water security. As a case in point, we analyze Jordan's surface water resources and agricultural water demand through 2100, considering the combined impacts of climate change and land-use change driven by the Syrian conflict. We use bias-corrected regional climate simulations as input to high-resolution hydrologic models to assess three drought types: meteorological (rainfall decrease), agricultural (soil moisture deficit), and hydrologic (streamflow decline) under future scenarios. The historical baseline period (1981-2010) is compared to the future (2011-2100), divided into three 30-year periods. Comparing the baseline period to 2070-2100, average temperature increases by 4.5°C, rainfall decreases by 30%, and multiple drought-type occurrences increase from ~8 in 30 years to ~25 in 30 years. There is a significant increase in the contemporaneous occurrence of multiple drought types along with an 80% increase in simultaneous warm and dry events. Watershed simulations of future transboundary Yarmouk-Jordan River flow from Syria show that Jordan would receive 51 to 75% less Yarmouk water compared to historical flow. Recovery of Syrian irrigated agriculture to pre-conflict conditions would produce twice the decline in transboundary flow as that due to climate change. In Jordan, the confluence of limited water supply, future drought, and transboundary hydrologic impacts of land use severely challenges achieving freshwater sustainability.
在那些预计气候变化会导致严重干旱的国家，以及那些严重依赖上游国家提供淡水的国家，人为干预和灾害所引发的气候干燥状况以及随之而来的跨界河流水文状况变化，会给区域水资源安全带来不确定性。例如，我们分析了到2100年约旦的地表水资源和农业用水需求，考虑了叙利亚冲突所驱动的气候变化和土地利用变化的综合影响。我们使用经过偏差校正的区域气候模拟结果作为高分辨率水文模型的输入，以评估未来情景下的三种干旱类型：气象干旱（降雨量减少）、农业干旱（土壤水分亏缺）和水文干旱（河流量下降）。将历史基准期（1981 - 2010年）与未来（2011 - 2100年）进行比较，未来分为三个30年时段。将基准期与2070 - 2100年进行比较，平均气温升高4.5°C，降雨量减少30%，多种干旱类型的发生次数从30年约8次增加到30年约25次。多种干旱类型同时发生的情况显著增加，同时暖干事件增加了80%。对未来叙利亚境内跨界的亚尔穆克河 - 约旦河水流的流域模拟表明，与历史流量相比，约旦获得的亚尔穆克河水量将减少51%至75%。叙利亚灌溉农业恢复到冲突前的状况，将使跨界河流量的下降幅度是气候变化所致下降幅度的两倍。在约旦，有限的供水、未来的干旱以及土地利用的跨界水文影响相互交织，严重挑战了实现淡水可持续性的目标。
