In recent years, frequent flood disasters have posed significant threats to human life and property. From 28 July to 1 August 2023, a basin-wide extreme flood occurred in the Haihe River Basin (23.7 flood). The Gravity Recovery and Climate Experiment satellite can effectively detect the spatiotemporal characteristics of terrestrial water storage anomalies (TWSA) and has been widely used in flood disaster monitoring. However, flood events usually occur on a submonthly scale. This study first utilizes near-real-time precipitation data to illustrate the evolution of the 23.7 extreme flood. We then reconstruct daily TWSA to improve the issues of coarse temporal resolution and data latency and further calculate wetness index (WI) to explore its flood warning. In addition, we analyze soil moisture storage anomalies to provide a comprehensive understanding of flood mechanisms. The study also compares the 2023 floods to a severe flood event in 2021. Results indicate that reconstructed daily TWSA increases by 143.43 mm in 6 days during the 23.7 flood, highlighting the high sensitivity of our approach to extreme events. Moreover, compared to daily runoff data, the WI consistently exceeds warning thresholds 2-3 days in advance, demonstrating the flood warning capability. The flood event 2021 is characterized by long duration and large precipitation extremes, whereas the 2023 flood affects a wider area. This study provides a reference for using daily TWSA to monitor short-term flood events and evaluate the flood warning potential of WI, aiming to enhance near-real-time flood monitoring and support flood prevention and damage mitigation efforts.

Identifying the changes in terrestrial water storage is essential for a comprehensive understanding of the regional hydrological mass balance under global climate change. This study used a partial least square regression model to fill the observation gaps between GRACE and GRACE-FO and obtained a complete series of terrestrial water storage anomaly data from April 2002 to December 2020 from southeast China. We investigated the variations in terrestrial water storage anomalies in the region and the influencing factors. The study revealed that terrestrial water storage (TWS) anomalies have been increasing in the region, with an average increase of 0.33 cm/yr (p < 0.01). The intra-annual variation showed a positive anomaly from March to September and a negative anomaly in other months. Terrestrial water storage anomalies increased in most regions (especially in the central and northern parts), whereas they decreased in the southern parts. In terms of the components, the soil moisture storage (SMS) contributes 58.3 % and the surface water storage (SWS, especially reservoirs water storage) contributes 41.4 % to the TWS. The study also found that changes in the precipitation explain approximately 71.7 % of the terrestrial water storage variation, and reservoirs contributes to the remaining 28.3 %. These results are essential for understanding the changes in the hydrological cycle and developing strategies for water management in Southeast China.

The southeastern Tibetan Plateau (SETP), which hosts the most extensive marine glaciers on the Tibetan Plateau (TP), exhibits enhanced sensitivity to climatic fluctuations. Under global warming, persistent glacier mass depletion within the SETP poses a risk to water resource security and sustainability in adjacent nations and regions. This study deployed a high-precision ICESat-2 satellite altimetry technique to evaluate SETP glacier thickness changes from 2018 to 2022. Our results show that the average change rate in glacier thickness in the SETP is -0.91 +/- 0.18 m/yr, and the corresponding glacier mass change is -7.61 +/- 1.52 Gt/yr. In the SETP, the glacier mass loss obtained via ICESat-2 data is larger than the mass change in total land water storage observed by the Gravity Recovery and Climate Experiment follow-on satellite (GRACE-FO), -5.13 +/- 2.55 Gt/yr, which underscores the changes occurring in other land water components, including snow (-0.44 +/- 0.09 Gt/yr), lakes (-0.06 +/- 0.02 Gt/yr), soil moisture (1.88 +/- 1.83 Gt/yr), and groundwater (1.45 +/- 0.70 Gt/yr), with a closure error of -0.35 Gt/yr. This demonstrates that this dramatic glacier mass loss is the main reason for the decrease in total land water storage in the SETP. Generally, there are decreasing trends in solid water storage (glacier and snow) against stable or increasing trends in liquid water storage (lakes, soil moisture, and groundwater) in the SETP. This persistent decrease in solid water is linked to the enhanced melting induced by rising temperatures. Given the decreasing trend in summer precipitation, the surge in liquid water in the SETP should be principally ascribed to the increased melting of solid water.

Study region: The Northwest inland basins of China (NWC).Study focus: Terrestrial water resources, especially groundwater resources, are the main source of water for human activities and for maintaining the stability of the ecological environment in NWC. Excessive consumption of water resources will seriously affect the sustainable utilization of water resources and ecological security in this region. Therefore, it is urgent to clarify the long-term changes in water storage in this area in order to handle the pressure of future water re-sources and the natural environment. Using GRACE satellite datasets and global hydrological models (GHMs) products, this study analyzed spatiotemporal variations in terrestrial water storage anomalies (TWSA), groundwater storage anomalies (GWSA), soil moisture, snow water equivalent, and canopy interception combined anomalies (SSCA) in NWC through the application of the water balance, trend decomposition, and empirical orthogonal decomposition methods. Furthermore, the driving factors of water storage change and feasible water resource manage-ment strategies were discussed. New hydrological insights for the region: TWSA in the NWC has experienced a continuous decline over the past nearly 40 years, while SSCA has shown a weak increasing trend (0.03 cm yr-1). Since the availability of glacial retreat data (2003-2016), glacial water storage in the NWC has decreased by 0.09 cm per year, while TWSA, SSCA, and GWSA have changed at rates of -0.25, 0.02, and -0.18 cm yr-1, respectively. The North Tianshan Rivers Basin has become one of the areas with the most severe groundwater depletion in China. 2005-2010 was a turning period in the changes of TWSA, followed by widespread water loss across the NWC. Glacier and snow melt are the most important factors for the decline of TWSA in the Tianshan mountains area, and over -exploitation of groundwater by human activities is a secondary factor. For other regions, Groundwater losses remain the most significant contributor to TWSA losses. The massive loss of water storage in the Tianshan Mountains area, especially the accelerated retreat of glaciers, will affect the stable water supply to the middle and lower reaches of the oasis region, perhaps leading to increased groundwater extraction, which will threaten regional water security and sustainable development. Developing a water-saving society and implementing inter-basin water transfer arefeasible ways to alleviate the water resource crisis. Conducting a comprehensive analysis of all inland rivers in China helps to facilitate horizontal comparisons between various basins, thereby providing more comprehensive insights of water storage fluctuations. The data on water storage changes, extending back to 1980, provide a longer-term perspective on water resource changes in the region, which can contribute to enhancing water resource security and ecological environ-mental protection.

Mountains are the water towers of the world, so it is critical to obtain accurate precipitation data for mountainous areas. Due to the complex topography of high mountainous areas, precipitation ground stations are sparse and unevenly distributed in such areas, so precipitation products such as remote sensing and reanalysis products are used to obtain gridded precipitation data for these areas. However, no single precipitation product performs best in all areas of mountainous regions. Therefore, this study first evaluated the performance of 12 precipitation products in estimating precipitation in the Qilian Mountains at the station scale and sub-basin scale, and then compared the performance of precipitation estimates for the Qilian Mountains generated by 8 multimodel averaging methods. The evaluation results for 29 meteorological stations in the Qilian Mountains showed that the China Meteorological Forcing Dataset product was the best-performing precipitation product, while the Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks-Cloud Classification System-Climate Data Record product was the worst-performing precipitation product. The evaluation results for 18 sub-basins showed that at these sub-basins, the WorldClim was the best-performing precipitation product, while the High Asia Refined analysis was the worst-performing precipitation product. Thus, station-scale evaluations may not necessarily be applicable to the basin scale. Multi-model averaging methods effectively improved the accuracy of precipitation estimates both at station scale and at sub-basin scale. The Granger-Ramanathan variant C was the best multi-model averaging method for estimating precipitation at station scale. As the Granger-Ramanathan methods allow negative weights, they are not recommended to interpolate the Granger-Ramanathan weight values of stations to grids. The Bayesian model averaging (BMA) was found to be the most suitable multi-model averaging method for estimating precipitation in the Qilian Mountains by interpolation of weight values of stations to grids. The precipitation estimates generated by BMA show that the mean annual precipitation in the Qilian Mountains from 2001 to 2018 was approximately 336.1 mm, and the annual precipitation during this period increased linearly by 2.4 mm per year.

Understanding terrestrial water storage (TWS) dynamics and associated drivers (e.g., climate variability, vegetation change, and human activities) across climate zones is essential for designing water resources management strategies in a changing environment. This study estimated TWS anomalies (TWSAs) based on the corrected Gravity Recovery and Climate Experiment (GRACE) gravity satellite data and derived driving factors for 214 watersheds across six climate zones in China. We evaluated the long-term trends and stationarities of TWSAs from 2004 to 2014 using the Mann-Kendall trend test and Augmented Dickey-Fuller stationarity test, respectively, and identified the key driving factors for TWSAs using the partial correlation analysis. The results indicated that increased TWSAs were observed in watersheds in tropical and subtropical climate zones, while decreased TWSAs were found in alpine and warm temperate watersheds. For tropical watersheds, increases in TWS were caused by increasing water conservation capacity as a result of large-scale plantations and the implementation of natural forest protection programs. For subtropical watersheds, TWS increments were driven by increasing precipitation and forestation. The decreasing tendency in TWS in warm temperate watersheds was related to intensive human activities. In the cold temperate zone, increased precipitation and soil moisture resulting from accelerated and advanced melting of frozen soils outweigh the above-ground evapotranspiration losses, which consequently led to the upward tendency in TWS in some watersheds (e.g., Xiaoxing'anling mountains). In the alpine climate zone, significant declines in TWS were caused by declined precipitation and soil moisture and increased evapotranspiration and glacier retreats due to global warming, as well as increased agriculture activities. These findings can provide critical scientific evidence and guidance for policymakers to design adaptive strategies and plans for watershed-scale water resources and forest management in different climate zones.

Understanding how groundwater storage (GWS) responds to climate change is essential for water resources management and future water availability in the Tibetan Plateau (TP). However, the dominant factor controlling long-term GWS changes remains unclear and its responses to climate change are not well understood. Here we combined multi-source datasets including in-situ measurements, satellite observations, global models, and reanalysis products to reveal that GWS increased at 5.59 +/- 1.44 Gt/yr during 2003-2016 while showing spatial heterogeneities with increasing trends in northern TP and glacial regions and declining trends in central and southern TP. The accelerated transformation from solid water (glaciers, snow, and permafrost; -17.72 +/- 1.53 Gt/yr) into liquid water provide more recharge to groundwater, dominating the total GWS increase. This study contributes to a better understanding of the hydrological cycle under climate change and provides key information for projecting water availability under different future scenarios in the TP.

Monitoring the variations in terrestrial water storage (TWS) is crucial for understanding the regional hydrological processes, which helps to allocate and manage basin-scale water resources efficiently. In this study, the impacts of climate change, glacier mass loss, and human activities on the variations in TWS of the Qaidam Basin over the period of 2002-2020 were investigated by using Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) data, and other hydrological and meteorological data. The results indicate that TWS anomalies (TWSA) derived from five GRACE solutions experienced significant increasing trends over the study period, with the change rates ranging from 4.85 to 6.90 mm/year (1.37 to 1.95 km(3)/year). The GRACE TWSA averaged from different GRACE solutions exhibited an increase at a rate of 5.83 +/- 0.12 mm/year (1.65 +/- 0.03 km(3)/year). Trends in individual components of TWS indicate that the increase in soil moisture (7.65 mm/year) contributed the most to the variations in TWS. Through comprehensive analysis, it was found that the temporal variations in TWS of the Qaidam Basin were dominated by the variations in precipitation, and the spatial variations in TWS of the Qaidam Basin were mostly driven by the increase in glacier meltwater due to climate warming, particularly in the Narin Gol Basin. In addition, the water consumption associated with human activities had relatively fewer impacts.

The northeastern Tibetan Plateau (NETP), bordering the endorheic lake basins and the Upper Yellow River region, has been disturbed by increasing human activities in recent years. The NETP water storage changes could be a combined effect of climate variability/change and human activities (e.g., reservoir operation). However, whether the human activities have evidently altered hydrological processes and become key drivers of total terrestrial water storage (TWS) changes in the NETP remains unclear. To explore the roles of human interventions in changing surface water storage (SWS) and thus influencing regional TWS changes in the NETP, in comparison with natural drivers, this study quantitatively disaggregated and compared the contributions of TWS changes from climate-dominated natural lakes and man-regulated reservoirs at different timescales. Time series of Gravity Recovery and Climate Experiment (GRACE) TWS anomalies (TWSA) exhibited an overall upward trend (0.78 +/- 0.06 Gt/yr, p < 0.01) with evident periodic fluctuations from April 2002 to August 2020. Although the GRACE TWSA was more substantially influenced by changes in natural lake water storage (0.96 +/- 0.02 Gt/ yr) rather than reservoirs (0.54 +/- 0.04 Gt/yr) in the long-term trend, the man-regulated reservoir water storage changes can significantly dominate the GRACE TWSA on interannual and intra-annual timescales, especially in the second sub-period (2013.01-2017.06; GRACE TWSA change rate:-1.82 +/- 0.29 Gt/yr, p < 0.01, in comparison with the change rate of reservoir water storage of-1.28 +/- 0.17 Gt/yr, and the natural lakes of 0.72 +/- 0.07 Gt/yr). In some abnormal years, the reservoir storage changes were even close to the overall signal of region-wide GRACE TWSA. In addition, the increase in soil moisture storage (long-term linear trend: 0.65 +/- 0.06 Gt/yr, p < 0.01) was also a key factor that cannot be neglected. Our results suggest that human activities are becoming one of the key factors influencing TWS changes in the NETP.

两极冰盖消融及其质量变化作为全球气候变化的重要指标之一，一直是联合国政府间专门气候委员会IPCC（Intergovernmental Panel on Climate Change）报告的重点关注内容.GRACE（Gravity Recovery and Climate Experiment, 2002年4月—2017年6月）和GRACE-FO（GRACE Follow-on, 2018年5月至今）重力卫星，作为监测两极冰盖质量变化最直接和有效的手段，存在近一年的观测间断期.因此本文提出联合Swarm三颗低轨卫星观测资料（2015年1月—2019年6月）和ARIMA-MC（Autoregressive Integrated Moving Average Model-Monte Carlo）预测方法来填补两组重力卫星间断期两极冰盖消融质量变化观测的时间序列，从而基于完整时间序列来研究两极冰盖质量时空变化规律.研究结果表明：（1）利用Swarm卫星反演得到的时变重力场信号和ARIMA-MC预测方法可以有效填补间断期两极冰盖消融质量变化的时间序列，但两种方法得到的结果也存在一定的差异；（2）...