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Study region: The Xiying River Basin is a typical inland mountainous watershed located in the Qilian Mountains. Study focus: This article reveals the change of runoff stable isotopes and their control mechanisms based on isotope data of different water bodies (precipitation, runoff, groundwater, and glacial snowmelt) in the Xiying River Basin from 2016 to 2021, combined with relevant meteorological observation data and the Normalized Vegetation Index (NDVI). New hydrological insights for the region: The results show that (1) meteorological factors control runoff isotope variations through controlling the evaporation process of runoff and the isotopic characteristics of recharge sources. (2) In areas with low vegetation cover, surface landscape features influence runoff isotopic composition by altering the isotopic characteristics of recharge sources. (3) In areas with high vegetation cover, surface vegetation cover affects runoff stable isotopes by controlling evapotranspiration processes. This study connects vegetation cover and runoff isotopes to explain the surface landscape control of runoff stable isotopes. It offers a more powerful reference for elucidating the factors influencing runoff isotopes in inland mountain watersheds.

In arid oasis regions, water resources are severely scarce, with agricultural water usage far exceeding that of more humid areas. As a result, assessing non-productive water losses in farmland becomes crucial for estimating the water requirements reliant on irrigation for oasis cultivation. From April 2018 to October 2021, we established an observation system in the Minqin Oasis farmland. By utilizing hydrogen and oxygen isotopes in precipitation, soil water, and maize stem xylem water, we quantified the non-productive water loss (FE) and soil water infiltration rate (fe) in maize fields. Our findings indicate: (1) The average non-productive losses from rainfall and irrigation in arid maize fields were 39 %, with peak losses reaching 58 %; (2) Non-productive losses due to evapotranspiration were mainly observed in June and July, while losses from infiltration predominantly occurred in April-May and August-September; (3) Crop evapotranspiration capacity emerged as a significant factor influencing evaporation losses, while individual irrigation amounts and rainfall determined soil infiltration losses. We believe that judiciously managing irrigation volume and adjusting irrigation strategies in arid farmlands could unlock substantial potential for conserving water resources.

Different types of mulch are often used in agricultural production to enhance soil moisture and improve crop yields. The question of which mulch provides superior water retention in arid regions, where water resources are scarce, is a major concern for agricultural production. We conducted observations and studies at a typical irrigated experimental station in an arid zone with four types of mulch, including liquid mulch (LM), biodegradable mulch (BM), ordinary black mulch (OBM), and ordinary white mulch (OWM), and plots with no mulch. Samples were collected and analyzed at 1, 3, 5, and 7 days after each rainfall or irrigation to obtain soil moisture changes and to analyze the effect of different mulches on soil moisture retention. The results showed that mulch cover was effective in retaining soil moisture compared to plots without mulch cover. Specifically, soil moisture was highest in the farmland with OWM during the observation period. OWM, OBM, and BM were all effective in reducing soil water evaporation and maintaining soil moisture. LM and BM were capable of utilizing rainfall to recharge soil water in a superior way, and polyethylene mulches (OBM and OWM) had a significant barrier impact on rainfall.

Global changes and human activities have significantly altered water cycle processes and water resource patterns in inland river basins in arid zones. New tools are needed to conduct more comprehensive and scientific assessments of basin water cycle processes and water resource patterns. Based on GRACE satellite and Landsat data, this study investigated terrestrial water storage changes and surface water area in the Shiyang River Drainage Basin from 2002 to 2021. It explored the effects of climate change and water conservancy construction on terrestrial water storage changes in the basin. The results of the study show that, although the surface water quantity in the Shiyang River basin has increased in the past 20 years, the overall decreasing trend of terrestrial water storage in the basin of the Shiyang River has an interannual decreasing rate of 0.01 cm/a. The decreasing trend of water storage in the midstream and downstream areas is more prominent. The change in precipitation controls the change in water storage in the Shiyang River Drainage Basin. Artificial water transfer has changed the spatial distribution of water resources in the basin of the Shiyang River. However, it still has not completely reversed the trend of decreasing water storage in the middle and lower reaches of the Shiyang River.

Gravity Recovery and Climate Experiment (GRACE) satellite data are widely used in drought studies. In this study, we quantified drought severity based on land terrestrial water storage (TWS) changes in GRACE data. We used the water storage deficit (WSD) and water storage deficit index (WSDI) to identify the drought events and evaluate the drought severity. The WSDI calculated by GRACE provides an effective assessment method when assessing the extent of drought over large areas under a lack of site data. The results show a total of 22 drought events in the central Asian dry zone during the study period. During spring and autumn, the droughts among these incidents occurred more frequently and severely. The longest and most severe drought occurred near the Caspian Sea. In the arid area of central Asia, the north of the region tended to be moist (the WSDI value was 0.04 year−1), and the south, east, and Caspian Sea area tended to be drier (the WSDI values were −0.07 year−1 in the south, −0.11 year−1 in the east, and −0.19 year−1 in the Caspian Sea). These study results can provide a key scientific basis for agricultural development, food security, and climate change response in the Asian arid zone.

Stable isotopes in precipitation can effectively reveal the process of atmospheric water circulation, serving as an effective tool for hydrological and water resources research, climate change, and ecosystem studies. The scarcity of stable isotope data in precipitation has hindered comprehension of regional hydrology, climate, and ecology due to discontinuities on a temporal scale and unevenness on a spatial scale. To this end, we collated stable hydrogen and oxygen isotope data in precipitation from 1930 stations in Eurasia from 1961 to 2022, totalling 51,752 data records. Stable isotopes in precipitation across various regions of Eurasia, as a whole, decrease with increasing latitude and distance from the coast. In the summer, stable isotopes in precipitation are relatively enriched, while in winter, they are relatively depleted. In recent decades, the stable isotope values of Eurasian precipitation show an overall trend of increasing variation with the advancement of years, which is associated with global warming. Geographical location, underlying surface conditions, seasons, and atmospheric circulation are all factors that determine the characteristics of stable isotopes in precipitation. The dataset of stable isotopes in Eurasian precipitation provides a powerful tool for understanding changes in regional atmospheric water circulation and assists in conducting hydrological, meteorological, and ecological studies in related regions. [ABSTRACT FROM AUTHOR]

Stable hydrogen and oxygen isotopes in atmospheric precipitation have the potential to identify abnormal weather events, and climate change will cause more intense and frequent high-temperature events, which already pose a threat to human health and the development of the global economy. Based on precipitation isotope data from 37 high-temperature events that occurred in various global regions between 2010 and 2022, this article examines the impacts of high-temperature events on stable precipitation isotopes. The results show that (1) stable precipitation isotopes are more enriched under the influence of high-temperature events than in the same month of previous years; the slope and intercept of the precipitation local meteoric water line (LMWL) are lower than in the same month of previous years and the global meteoric water line (GMWL); and the precipitation d-excess is lower than the global average. (2) Temperature is the primary meteorological factor that produces abnormal variations in precipitation isotopes under the influence of high-temperature events, and the impact of temperature on precipitation isotopes is significantly amplified (P<0.05). (3) Furthermore, variations in atmospheric circulation patterns, water vapor transport fluxes, regional water vapor background, and surface morphology can lead to regional differences in anomalous variations in precipitation isotopes. This study reveals the impact of high temperatures on precipitation isotopes and their mechanisms, which is instructive for disentangling the influence of high-temperature events on water cycle processes. It may also offer fresh perspectives for the reconstruction of paleo-high-temperature events based on isotopes. [ABSTRACT FROM AUTHOR]

Mountainous areas are the main water-producing and source areas of rivers. Global climate change is transforming the distribution of plants and forms of water use. Therefore, a clear understanding of evapotranspiration in mountainous forest zone is key for understanding the ecohydrological effect of vegetation and its influence on the water cycle of the watershed. We quantified the evapotranspiration processes in the forest belts of the Qilian Mountains as well as their contribution to runoff yield and concentration based on precipitation, soil water, and plant water samples and experimental data. The study showed that transpiration of Qinghai spruce accounted for the highest proportion of evapotranspiration in the entire Qinghai spruce forest ecosystem, with an average of 79 %, which means that transpiration is much greater than evaporation. Soil water content and air humidity were the dominant factors influencing evapotranspiration in Qinghai spruce forest belts. The growing season of Qinghai spruce is characterized by greater evapotranspiration than precipitation in each month. Consequently, the forest zone does not yield flows in the eastern part of the Qilian Mountains. The warming of global temperatures and human activities are likely to trigger shifts in the distribution areas and evapotranspiration regimes of Qinghai spruce, which in turn will lead to a change in water resource patterns in the basin. [ABSTRACT FROM AUTHOR]