Increased precipitation and vegetation cover synergistically enhanced the availability and effectiveness of water resources in a dryland region

• Published in: Journal of hydrology (Amsterdam) Vol. 654; p. 132812
• Main Authors: Gao, Siqi, Lü, Yihe, Jiang, Xiaohui
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2025
• Subjects: arid lands; Dryland region; ecological restoration; evaporation; evapotranspiration; Evapotranspiration components; normalized difference vegetation index; risk; temporal variation; Terrestrial water resource availability; the Yellow River Basin; transpiration; vegetation cover; water management; watersheds; Yellow River; Yellow River; Evapotranspiration components; Terrestrial water resource availability; Dryland region; the Yellow River Basin
• ISSN: 0022-1694
• DOI: 10.1016/j.jhydrol.2025.132812

•Distinguished patterns of changes and causes of evapotranspiration components.•Increased precipitation & vegetation cover boost water availability & effectiveness.•Current precipitation conditions can support increased vegetation cover in the MRYRB.•Monitor vegetation water demand risks under precipitation changes in drylands.•Enhance precipitation or optimize vegetation structure to reduce ineffective ET. Water resources are the primary limiting factor in restoring vegetation, particularly in dryland regions. Evapotranspiration (ET) is an important link among earth systems, and changes in ET affect water resources’ spatial and temporal distribution as well as the characteristics of changes in vegetation cover. After vegetation restoration projects were implemented in the middle reaches of the Yellow River Basin (MRYRB), issues such as how the ET process has been affected and how the terrestrial available water resources have changed remain largely unknown. To address this knowledge gap, we analyzed the spatial and temporal variability and influencing factors in ET and its components (transpiration (T), interception evaporation loss (EI), and bare-soil evaporation (EB)) in the MRYRB, and thus explored changes in the terrestrial water resources’ effectiveness and availability there. The results showed that from 2000 to 2020, ET showed an increasing trend at the rate of 2.11 mm yr−1. T, EI, and T/ET showed an increasing trend of 3.88 mm yr−1, 0.63 mm yr−1, and 0.0054 yr−1, respectively, and EB showed a decreasing trend of −2.58 mm yr−1. The increase in T was found to be the main reason for the increased ET in the MRYRB. As an effective water resource used in the process of increasing vegetation cover in the MRYRB, T was affected primarily by precipitation (P) (path coefficient of 0.502) and normalized difference vegetation index (NDVI) (path coefficient of 0.409), and the T/ET was affected mainly by NDVI (path coefficient of 0.524). In addition, the principal factor that affected EB and EI was also NDVI, with path coefficients of −0.631 and 0.381, respectively. Except for the direct influence, all factors promote or inhibit ET components indirectly by influencing vegetation growth. It was also found that the increase in P determined the increase in terrestrial available water resources (P-ET) at a rate of 2.44 mm yr−1. Therefore, increased precipitation and vegetation cover synergistically enhanced water resources’ availability and effectiveness. However, it was still necessary to direct attention to the risk of vegetation’s water use under future precipitation changes and promote vegetation restoration subject to water resource limits. The results of the study have important implications for vegetation restoration and water resource management in dryland regions such as the MRYRB under future changing environments.