Lakes are commonly accepted as a sensitive indicator of regional climate change, including the Tibetan Plateau (TP). This study took the Ranwu Lake, located in the southeastern TP, as the research object to investigate the relationship between the lake and regional hydroclimatological regimes. The well-known Budyko framework was utilized to explore the relationship and its causes. The results showed air temperature, evapotranspiration and potential evapotranspiration in the Ranwu Lake Basin generally increased, while precipitation, soil moisture, and glacier area decreased. The Budyko space indicated that the basin experienced an obviously drying phase first, and then a slightly wetting phase. An overall increase in lake area appears inconsistent with the drying phase of the basin climate. The inconsistency is attributable to the significant expansion of proglacial lakes due to glacial melting, possibly driven by the Atlantic Multidecadal Oscillation. Our findings should be helpful for understanding the complicated relationships between lakes and climate, and beneficial to water resources management under changing climates, especially in glacier basins.

Lakes are known as sentinels of climate change, but their responses may differ from one to another leading to different strategies in lake protection. It is particularly the case in the Tibetan Plateau (TP) of multiple hydrological processes. We employed the Budyko framework to study Tibetan lakes from two lake-basins of contrasting climates for the period between 1980 and 2022: Taro Co Basin (TCB) in a sub-arid climate, and Ranwu Lake Basin (RLB) in a sub-humid climate. Our results showed that total lake area, surface air temperature, evapotranspiration, and potential evapotranspiration increased in both lake-basins, while precipitation and soil moisture increased in the TCB but decreased in the RLB. In the Budyko space, two basins had contrast hydroclimatic trajectories in terms of aridity and evaporative index. The TCB shifted from wetting to drying trend, while the RLB from drying to wetting in early 2000s. Notably, lake change was generally consistent with the drying/wetting phases in the TCB, but in contrast with that in the RLB, which can be attributed to warming- induced glacier melting. Despite of significant correlation with the large-scale atmospheric oscillations, it turned to be more plausible if lake area changes were substituted with basin's hydroclimatic trajectories. Among the large-scale oscillations, El Nino-Southern o-Southern Oscillation (ENSO) is the most dominant control of lake trends and their drying/wetting shifts. Our findings offer a valuable insight into lake responses to climate change in the TP and other regions.

The retreat of glaciers has altered hydrological processes in cryospheric regions and affects water resources at the basin scale. It is necessary to elucidate the contributions of environmental changes to evapotranspiration (ET) variation in cryospheric-dominated regions. Considering the upper reach of the Shule River Basin as a typical cryospheric-dominated watershed, an extended Budyko framework addressing glacier change was constructed and applied to investigate the sensitivity and contribution of changes in environmental variables to ET variation. The annual ET showed a significant upward trend of 1.158 mm yr(-1) during 1982-2015 in the study area. ET was found to be the most sensitive to precipitation (P), followed by the controlling parameter (w), which reflects the integrated effects of landscape alterations, potential evapotranspiration (ET0), and glacier change ( increment W). The increase in P was the dominant factor influencing the increase in ET, with a contribution of 112.64%, while the decrease in w largely offset its effect. The contributions of P and ET0 to ET change decreased, whereas that of w increased when considering glaciers using the extended Budyko framework. The change in glaciers played a clear role in ET change and hydrological processes, which cannot be ignored in cryospheric watersheds. These findings are helpful for better understanding changes in water resources in cryospheric regions.

Alpine areas play a substantial role in supplying the world's water resources. The hydrological cycle in these areas has been experiencing notable alterations owing to climate change. However, the present comprehension of how water yield capacity (WYC) responds to climate change at varying elevations within alpine basins is impeded due to the complex terrain and simplified representation of coupled water-energy processes in traditional hydrological models. Through integrating the Weather Research and Forecasting hydrological modeling system (WRF-Hydro) and Budyko framework, this study quantitatively assessed the influence of climate change on WYC across different elevations in a Tibetan Plateau alpine basin, named Xiying River Basin (XRB). The results indicated the WRF-Hydro adeptly reproduced the streamflow and evapotranspiration (ET) within the XRB. The combination of the WRF-Hydro model allows the Budyko framework, traditionally limited to the watershed scale, to be applicable at the grid scale. We found that the XRB underwent substantial climate change from 1980 to 2015, and there existed an abrupt change in 1997. Climate change caused the WYC reduced by -17.06% during the post-1997 period (1998-2015), compared to the pre-1997 period (1980-1997). Additionally, all elevation bands displayed the WYC reductions, ranging from -3.69% to -24.31%, with diminishing magnitude at higher elevations. This WYC reduction is primarily attributed to an increase of 11.38% in ET. Although ET and precipitation increased with elevation, the former consistently exceeded the latter, resulting in decreasing water deficits and an altitudinal gradient of the WYC reduction. Besides the increasing vapor pressure deficit and decreasing albedo, our findings emphasized the significance of precipitation event timing in influencing WYC. The longer time intervals between precipitation events in the XRB led to more soil moisture loss through ET. These findings shed valuable implications for policymakers, offering guidance for the formulation of sustainable policies for water resource management and ecological conservation.

Glacier shrinkage and permafrost degradation have significantly altered the hydrological processes in cryospheric regions through releasing water and absorbing more energy from the ground. Considering the upper Shule River Basin (USRB) as a typical cryospheric-dominated watershed on the Tibetan Plateau, an extended Budyko framework considering glacier shrinkage and permafrost degradation was constructed to investigate their contributions to runoff change. Runoff exhibited a significant increasing trend during 1970-2015, with a tipping point appearing around 1998. Thus, 1970-1998 and 1999-2015 were identified as the baseline and changing periods, respectively. During the two periods, runoff was the most sensitive to landscape alteration, followed by precipitation. The increase in precipitation contributed 93.1 % to the increase in runoff, while its effect was partially offset by the negative contribution of potential evapotranspiration (-3.9 %). Glacier shrinkage and permafrost degradation accounted for a 8.0 % and 24.8 % increase in runoff, respectively. Part of these increases were offset by changes in other landscape factors (-22.0 %). Our study elucidates the impacts of glacier shrinkage and permafrost degradation on hydrological processes in cryospheric basins.

The effects of catchment characteristics and climate variables on water partitioning into evapotranspiration and runoff can be evaluated using the Budyko framework. However, the influence of glaciers on catchment characteristics within the framework has yet been adequately investigated. Here we extend the Budyko framework and apply the elasticity method to examine the effects of glaciers on runoff between 2001 and 2010 in 25 upstream catchments of the Tarim River Basin in western China. The consideration of glacier mass balance and glacier fraction improves the performance of the Budyko framework, especially for the catchments with a high glacier fraction. We found that the catchment characteristic parameter u was strongly affected by glacier fraction, and it changes from 1.15 to 2.09 when glacier fraction decreases from 0.4191 to 0.0005. This also reflects the change in water-energy partitioning that eventually effects on evapotranspiration and runoff. We further assessed the average runoff responses to changes in precipitation, potential evapotranspiration, glacier mass balance, and glacier fraction in the 25 catchments. Although the runoff appears most sensitive to precipitation in average, its sensitivity to glacier mass balance and glacier area in fact rises from -0.07% to 0.17% and about 0-0.54%, respectively, when the glacier fraction increases from 0.0005 to 0.4191, further demonstrating the increasing influence of glaciers when the fraction becomes larger. After all, the inclusion of glacier factors in the Budyko framework allows us to understand more about the impacts and contributions of glaciers to runoff at a catchment scale.

The source region of the Yellow River (SRYR) is greatly important for water resources throughout the entire Yellow River Basin. Streamfiow in the SRYR has experienced great changes over the past few decades, which is closely related to the frozen ground degradation; however, the extent of this influence is, still unclear. In this study, the air freezing index (DDFa) is selected as an indicator for the degree of frozen ground degradation. A water-energy balance equation within the Budyko framework is employed to quantify the streamflow response to the direct impact of climate change, which manifests as changes in the precipitation and potential evapotranspiration, as well as the impact of frozen ground degradation, which can be regarded as part of the indirect impact of climate change. The results show that the direct impact of climate change and the impact of frozen ground degradation can explain 55% and 33%, respectively, of the streamflow decrease for the entire SRYR from Period 1 (1965-1989) to Period 2 (1990-2003). In the permafrost-dominated region upstream of the Jimai hydrological station, the impact of frozen ground degradation can explain 71% of the streamflow decrease. From Period 2 (1990-2003) to Period 3 (2004-2015), the observed streamflow did not increase as much as the precipitation; this could be attributed to the combined effects of increasing potential evapotranspiration and more importantly, frozen ground degradation. Frozen ground degradation could influence streamflow by increasing the groundwater storage when the active layer thickness increases in permafrost-dominated regions. These findings will help develop a better understanding of the impact of frozen ground degradation on water resources in the Tibetan Plateau. (C) 2018 Elsevier B.V. All rights reserved.