Quantifying Time-Lagged Vegetation Responses to Hydroclimatic Factors in Dam-Influenced Arid Regions Using VAR...

Effective management of dry ecosystems requires an understanding of vegetation dynamics, especially in areas affected by dam-induced hydrological alteration. To provide valuable information on the delayed restoration of ecosystems in arid regions has been affected by dam-induced hydrological alteration, the current study looks at the lagged vegetation responses to hydroclimatic factors. Vegetation dynamics were analyzed using the Normalized Difference Vegetation Index (NDVI) in relation to precipitation, temperature, runoff, and total water storage (TWS) across four dam-impacted basins in southern Saudi Arabia (Hali, Baish, Qanuna, and Al-Ahsabah). A Vector Autoregression (VAR) model applied to remote sensing data (2003-2024) revealed that dam construction significantly increased the vegetation response lag, extending from 2-3 months in the pre-dam period (2003-2009) to 4-5 months post-dam (2010-2024). This shift highlights how dams disrupt the natural coupling between hydroclimatic inputs and vegetation growth, with important consequences for ecosystem recovery and water management in arid regions. These findings highlight the vegetation response and hydrological cycle alterations induced by dams, stressing the lagged vegetation recovery in dammed basins. This has significant implications for water resource management and ecosystem resilience in arid regions. Time-lag analysis can guide dam operations, improve irrigation planning, and support ecosystem monitoring.