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Terrestrial Water Storage (TWS) plays a pivotal role in water resource management by providing a comprehensive measure of both surface water and groundwater availability. This study investigates changes in TWS driven by human activities from 2003 to 2023, and forecasts future TWS trends under various climate change and development scenarios. Our findings reveal a continuous decline in China's TWS since 2003, with an average annual decrease of approximately 1.36 mm. This reduction is primarily attributed to the combined effects of climate change and human activities, including irrigation, industrial water use, and domestic water consumption. Notably, TWS exhibits significant seasonal and annual fluctuations, with variations ranging ±10 mm. For the future period (2024-2030), we project greater disparities between water resource supply and demand in specific years for the Songliao, Southwest, and Yangtze basins. Consequently, future water resource management must prioritize water conservation during wet seasons, particularly in years when supply-demand conflicts for limited water resources intensify. This study is valuable for effective planning and sustainable utilization of water resources., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Chunmiao Zheng reports financial support was provided by the Ministry of Education of China and the National Natural Science Foundation of China. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The Himalayas are critical for supplying water for ∼2 billion people who live downstream, and available water is highly sensitive to climate change. The role of the groundwater system in sustaining the northern Himalayan rivers remains unknown, and this compromises Asia's future water sustainability. Here, we quantify the spatiotemporal contribution of groundwater to river flows in the Yarlung Zangbo Basin (upper reaches of Brahmaputra). Our results show that the groundwater recharge represents ∼23% of mean annual precipitation, translating into ∼30 km3/yr of baseflow, which contributes ∼55% of the total river discharge in the upstream reaches to ∼27% in the downstream reaches. The percentage of groundwater contribution is inversely related to topographic steepness and total precipitation, with the steepest topography and highest precipitation in the eastern Himalayas. This study fills a knowledge gap on groundwater in the Himalayas and is a foundation for projecting water changes under climatic warming. Plain Language Summary: Major rivers flowing from the Himalayan Plateau provide critical water resources for 2 billion people who live downstream and rely on Himalayan rivers for water supply, irrigation, hydropower and in‐stream flows for aquatic habit. While groundwater discharge to rivers is known to contribute to available water resources, how much Himalayan rivers depend on groundwater is poorly known. This study models the spatial groundwater flow and discharge volume to the Yarlung Zangbo, the largest river of the Himalayas in China, based on long‐term climate and streamflow observations. We map the patterns of groundwater flow paths, water table elevations, recharge, and discharge to rivers. We estimate that ∼55% of the total river discharge in the upstream reaches in the central Himalayas is sustained by groundwater and ∼27% in the downstream reaches in the eastern Himalayas. Groundwater aquifer recharge totals at least ∼9 km3 during the monsoon season (May–October) and this sustains river low flows during dry season (November–April). This study fills a knowledge gap on subsurface flow processes in the northern Himalayas and provides a baseline for comparing changes in the stream water flow under climatic warming over vulnerable mountainous headwater regions. Key Points: Groundwater supports dry season streamflow, providing 55%–27% annual water to central and eastern Himalayan rivers, respectivelyLow flows between November and April are sustained by groundwater storage resulting from recharge between May and OctoberThe percentage groundwater contribution is inversely related to steepness of the topography and total precipitation, in combination [ABSTRACT FROM AUTHOR]

Groundwater is expected to be more vulnerable to water-quality degradation in the future due to rapid urbanization. However, despite knowledge that protecting future groundwater resources is necessary for sustainable groundwater resource development, little is known about the role of groundwater policy in influencing the spatial distribution of urbanization. This study sheds light on how a policy that protects vulnerable groundwater could affect the distribution of urban expansion. Groundwater vulnerability to pollution under future climate change scenarios is used as a factor to generate urban expansion probability maps for China. The results indicate that there will be a significant and uneven urban growth by 2030, if current trends in urban expansion continue. The amount of urban land in 2030 will range from 2.9 to 4.2 times the urban area in 2010. Meanwhile, the urban expansion probability maps for projections with and without consideration of groundwater vulnerability in urban suitability are compared. The comparation shows that consideration of a groundwater policy would significantly alter the future spatial distribution of urban areas. Even with a weight of only 10% for groundwater vulnerability in the urban suitability consideration, the percentage of change area in the urban expansion probability distribution map can be as high as 60%. The probabilities of urban expansion are forecast to gradually transfer from the southeast coastal areas to inland areas as higher weight (from 10% to 50%) of groundwater vulnerability is given to urban suitability consideration. Our study demonstrates that groundwater protection from urbanization pressures can be achieved, provides support for policy and decision makers in evaluating options to modify existing urban expansion policies, and concludes that groundwater protection at the macro-scale is an appropriate policy goal. [ABSTRACT FROM AUTHOR]