Understanding Differential Response of Vegetation Biophysical Attributes to the Groundwater Storage Change across Climates and Ecosystems

This dissertation examines groundwater storage variability, vegetation biophysical responses, and the influences of teleconnection factors on hydroclimatological processes in the Indian subcontinent. The four manuscripts address various aspects of these interconnected topics, each offering unique insights and methodologies to deepen our understanding of groundwa-ter-vegetation-climate interactions. Manuscript 1 explores groundwater storage variability using GRACE and in situ data across drought-prone regions in India, Australia, and Belgium, highlighting the influence of both natural and anthropogenic factors. It emphasizes the role of GRACE data in supplementing measurements where in situ data is limited. Manuscript 2 investigates the sensitivity of vegetation biophysical attributes to groundwater depletion, utilizing remote sensing data to analyze how groundwater availability impacts veg-etation health across different ecosystems. The findings underscore the importance of inte-grated water management to mitigate adverse effects on agriculture and natural ecosystems. Manuscript 3 examines the temporal sensitivity of vegetation to hydroclimatological varia-bles, such as soil moisture and groundwater. By exploring how vegetation responses vary across different time scales, this manuscript provides insights into the adaptive mechanisms of ecosystems to climatic changes. Manuscript 4 explores the teleconnections between oceanic-atmospheric phenomena, such as ENSO and IOD, and their impact on regional hydroclimatology and vegetation. The findings illustrate the importance of incorporating teleconnection information into predictive models to enhance water resource management in response to climate variability. Together, these manuscripts illustrate the complex interplay between groundwater storage, vegetation health, and climatic factors. The findings have significant implications for hydrol-ogy, agronomy, and climate adaptation, emphasizing the importance of integrating remote sensing and in situ approaches to monitor and manage water resources effectively. This work provides valuable insights for enhancing ecosystem resilience and ensuring sustainable water resources in drought-prone regions. The cumulative contributions of this dissertation include: 1) demonstrating the effectiveness of GRACE data in monitoring groundwater variability, 2) highlighting the role of groundwa-ter in sustaining vegetation during periods of scarcity, 3) elucidating vegetation sensitivity to different hydroclimatological variables, and 4) uncovering the influence of teleconnection phenomena on regional hydroclimatology. These insights aim to inform policy decisions and guide effective water management amidst climate change.