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In recent decades, the Loess Plateau has undergone rapid urbanization alongside extensive afforestation efforts aimed at controlling soil erosion. These large-scale land use changes have inevitably affected the region's hydrological cycle. Despite these changes, the impact on groundwater has not been thoroughly investigated. This study aims to examine the spatial and temporal evolution of groundwater storage (GWS) in the Loess Plateau from 2003 to 2022, identify the driving factors behind these changes, and evaluate the sustainability of groundwater levels through the Reliability–Resilience–Vulnerability framework. GWS changes were estimated using GRACE gravity satellite data and the Global Land Assimilation Dataset (GLDAS). Our study also analyzed the drivers of GWS evolution by integrating land use change data, ERA5-Land reanalysis data, and various statistical data. Our findings indicate a decline in GWS at a rate of −6.9 ± 3.84 mm/yr. Seasonal variations show that the GWS is relatively higher in spring and autumn, but lower in summer and winter. The eastern part of the Loess Plateau in particular is experiencing a rate of decline that is 150% of that of the overall regional average. Groundwater storage in the Loess Plateau is currently at a critically unsustainable level, with conditions in the west being more favorable compared to the central and eastern regions. Climate factors such as precipitation, evaporation, and runoff did not show a significant correlation with GWS changes. Increases in forest areas and water consumption together explained 95.8% of the changes in GWS, with forest area growth being the dominant factor. Human activities are identified as the main cause of GWS decline. This study's findings improve our understanding of GWS dynamics in the Loess Plateau and offer a scientific basis for formulating groundwater resource management and ecological restoration policies in the region. [ABSTRACT FROM AUTHOR]

【Background and objective】 Continuously pumping groundwater over the past half century for crop production in northern China has resulted in a series of environmental and ecological issues. The shortage of freshwater resources has become a bottleneck in socioeconomic development of this region. Improving groundwater management is important not only to its sustainable use but also to keeping ecosystems in this region function. Achieving this goal needs to understand how groundwater dynamics responds to environmental changes, as well as its consequent spatial distribution. The objective of this paper is to demonstrate how the SWAT model can be used to evaluate groundwater resource and its spatial distribution at regional scale. 【Method】 We took Jinghe basin as an example. Groundwater flow, surface runoff and their underlying driving factors were simulated using the SWAT model. Monthly measured runoff from hydrological stations at Jingchuan, Yangjiaping and Zhangjiashan was used to calibrated the model parameters; the calibrated model was then used to evaluate changes in groundwater depth, shallow groundwater resource, as well as extractable groundwater in the basin. 【Result】 The calibrated model correctly reproduced the groundwater dynamics in the basin, with R2 and NS between the measured and simulated runoff being 0.83 and 0.71, respectively. The distribution of shallow groundwater depth varied widely in the basin, but it has been in decline. From 2009 to 2016, the shallow groundwater resource had reduced by 6.59 billion m3, decreasing at an average rate of 0.051 billion m3/month. We found that the average recharge rate to the groundwater in the basin was 0.344 billion m3/a, the average subsurface runoff modulus was 0.21 L/(s·km2), and the extractable groundwater resource was 0.189 billion m3/a. 【Conclusion】 The SWAT model is capable of modelling regional surface runoff and shallow groundwater dynamics. It can be used to evaluate groundwater resources and the response of groundwater dynamics to environmental change.

【Background】 Spatiotemporal variation in precipitation is the consequence of a combined impact of regional climate and ecological environment. Global climate change over the past few decades has resulted in a change in precipitation pattern in many regions including Gansu, a province in China characterized by co-existence of arid climate in the west, monsoon climate in the east and alpine climate in the Qinghai-Tibet plateau. This combination makes the ecological and environment systems in Gansu fragile and susceptible to climate change. 【Objective】 The purpose of this work is to analyze the spatial change in precipitation over the province since 1961 as sell as the underlying mechanisms, especially the impact of global warming and anthropogenic activities. 【Method】 Precipitation measured from 59 meteorological stations from 1961 to 2018 across the province was analyzed using the PCI index, the wavelet analysis, MK test and other methods, from which we calculated its characteristics including period of precipitation, abnormal changes as well as trends in its spatiotemporal variation using the sliding t test. 【Result】 The annual precipitation decreased from the east to the west across the province. The intra-annual variation in the precipitation had increased from 1961 to 2018. We identified five periods in the precipitation: 28 years, 22 years, 12 years and 5 years, with the 28 year period most identifiable. Abrupt change in precipitation occurred in the middle 1960s, the early 1970s, the middle 1980s and the early 1990s. Precipitation in the west of the province had been increasing at 0.45 mm/a, while that in the central, south and east parts of the province had been in decline at 0.82 mm/a, 0.81 mm/a and 0.93 mm/a, respectively, until 1990s. But since the 1990s, the precipitation in all regions over the province has been in increase, especially in the east area where the precipitation has been increasing at 3.74 mm/a. 【Conclusion】 The precipitation in Gansu province over the past 60 years showed periodic and had witnessed both extreme rainfalls and droughts. There is a distinguishable difference in temporal change in precipitation between the west and central-east. Since the 1990s, the precipitation in the province has increased significantly. Our results have important implications for improving ecosystem services and alleviating disasters induced by climate changes, apart from providing a baseline database for meteorological, ecohydrological researches in this region and beyond.