Causes of changes in actual evapotranspiration and terrestrial water storage over the Eurasian inland basins

• Published in: Hydrological processes 2022-01, Vol.36 (1), p.n/a
• Main Author: Liu, Zhaofei
• Format: Article
• Language: English
• Subjects: actual evapotranspiration; Basins; Central Asia; Climate change; Consumption; continental river basin; Evapotranspiration; Glacial runoff; Glacier melting; global precipitation measurement; Global warming; Groundwater; Groundwater irrigation; Groundwater runoff; hydrological budget; Hydrology; inland closed basin; Inland waters; Lake basins; Lakes; Ocean basins; Plateaus; Potential evapotranspiration; Precipitation; Qinghai‐Tibet plateau; River basins; Rivers; Runoff; Structural basins; Trends; water balance; Water resources; Water storage; Water supply
• ISSN: 0885-6087; 1099-1085
• DOI: 10.1002/hyp.14482

The climate of the Eurasian inland basins (EIB) is characterized by limited precipitation and high potential evapotranspiration, making water storage in the EIB vulnerable to global warming and human activities. There is increasing evidence regarding varying trends in water storage across different regions; however, a consistent conclusion on the main attributes of these trends is lacking. Based on the hydrological budget in a closed inland basin, the main attributes of changes in actual evapotranspiration (AET) and terrestrial water storage (TWS) were identified for the EIBs and each closed basin. In the EIB and most of its closed basins (13/16), the TWS and AET showed significantly decreasing and non‐significant increasing trends, respectively. The primary cause underlying the significantly decreasing TWS in the EIB was the increase in AET. Approximately 70% of the increase in AET was attributed to increased irrigation diversions from groundwater and glacial melt runoff. At the basin scale, similar to the EIB, changes in AET were the predominant factor driving changes in TWS in most basins, with the exception of the Balkhash Lake basin (BLB), Iran inland river basin (IIRB), Qaidam basin (QB) and Turgay River basin (TuRB). In these basins, changes in precipitation largely contributed to the TWS changes. The AET consumption of other water resources was the main factor contributing to AET changes in seven of the 16 basins, including the Aral Sea, Caspian Sea, Junggar, Monglia Plateau, Qiangtang Plateau and Tarim River basins. The increase in precipitation contributed more than 60% of the increasing AET in four of the 16 basins, particularly in the Helmand River basin and QB (>90%). Changes in precipitation and consumption by other water supply sources contributed to approximately half of the AET changes in the other five basins, including the Inner Mongolia Plateau basin, Issyk‐Kul Sarysu basin, BLB, IIRB and TuRB. The main reason of water storage and actual evapotranspiration change is identified. The significantly decreasing water storage was mainly caused by increasing AET. The increase in AET is mainly caused by increased irrigations and glacial melt runoff.