Understanding changes in the water budget driven by climate change in cryospheric‐dominated watershed of the northeast Tibetan Plateau, China

Abstract

Glacial retreat and the thawing of permafrost due to climate warming have altered the hydrological cycle in cryospheric‐dominated watersheds. In this study, we analysed the impacts of climate change on the water budget for the upstream of the Shule River Basin on the northeast Tibetan Plateau. The results showed that temperature and precipitation increased significantly during 1957–2010 in the study area. The hydrological cycle in the study area has intensified and accelerated under recent climate change. The average increasing rate of discharge in the upstream of the Shule River Basin was 7.9 × 106 m3/year during 1957–2010. As the mean annual glacier mass balance lost −62.4 mm/year, the impact of glacier discharge on river flow has increased, especially after the 2000s. The contribution of glacier melt to discharge was approximately 187.99 × 108 m3 or 33.4% of the total discharge over the study period. The results suggested that the impact of warming overcome the effect of precipitation increase on run‐off increase during the study period. The evapotranspiration (ET) increased during 1957–2010 with a rate of 13.4 mm/10 years. On the basis of water balance and the Gravity Recovery and Climate Experiment and the Global Land Data Assimilation System data, the total water storage change showed a decreasing trend, whereas groundwater increased dramatically after 2006. As permafrost has degraded under climate warming, surface water can infiltrate deep into the ground, thus changing both the watershed storage and the mechanisms of discharge generation. Both the change in terrestrial water storage and changes in groundwater have had a strong control on surface discharge in the upstream of the Shule River Basin. Future trends in run‐off are forecasted based on climate scenarios. It is suggested that the impact of warming will overcome the effect of precipitation increase on run‐off in the study area. Further studies such as this will improve understanding of water balance in cold high‐elevation regions.

Understanding the effects of climate warming on streamflow and active groundwater storage in an alpine catchment: the upper Lhasa River

“…In general, permafrost thaw in arctic basins has resulted in a general upward trend of 0.7 % a −1 -0.9 % a −1 in the groundwater contribution to streamflow, although with no pervasive change in total annual runoff (Walvoord and Striegl, 2007). Similar results have also been found in the central and northern TP (Liu et al, 2011;Niu et al, 2016;Xu et al, 2019). Moreover, a slowdown in baseflow recession was found in the northeastern and central TP (Niu et al, 2011(Niu et al, , 2016Wang et al, 2017), in northeastern China (Duan et al, 2017) and in Arctic rivers (Lyon et al, 2009;Lyon and Destouni, 2010;Walvoord and Kurylyk, 2016).…”

“…However, the TP has experienced a significant warming period over the last 50 years (Kang et al, 2010;Liu and Chen, 2000). Along with rising temperature, major warming-induced changes have occurred over the TP, such as glacier retreat (Yao et al, 2004(Yao et al, , 2007 and frozen ground degradation (Wu and Zhang, 2008;Xu et al, 2019). Hence, it is of great importance to elucidate how climate warming Published by Copernicus Publications on behalf of the European Geosciences Union.…”

“…Since the 1990s, most glaciers across the TP have retreated rapidly due to global warming, and this has caused an increase of more than 5.5 % in river runoff from the plateau (Yao et al, 2007). Meltwater is the key contributor to streamflow increase, especially in headwater catchments with larger glacier coverage (> 5 %) (Bibi et al, 2018;Xu et al, 2019). For example, the total discharge increase of 2.7 %-22.4 % that is mainly due to increased glacier melt in the upper Brahmaputra (also known as the Yarlung Tsangpo) accounts for more than half of the total discharge increase (Su et al, 2016).…”

“…Generally, in alpine regions, glacier retreat and permafrost thawing that is triggered by climate warming is changing the hydrological processes of storage and discharge. However, direct measurements of changes in permafrost depth or catchment aquifer storage are still difficult to perform at the catchment scale (Xu et al, 2019;Staudinger, 2017;Käser and Hunkeler, 2016). Although their resolution and accuracy are relatively low, GRACE data have always been adopted to as-sess total groundwater storage changes (Green et al, 2011).…”

“…More importantly, quantitatively characterizing storage properties and sensitivity to climate warming in cold alpine catchments is desired for local water as well as downstream water management (Staudinger, 2017). Xu et al (2019) used a simple ratio of the maximum and minimum runoff to indirectly indicate the change in storage capacity as well as the effects of permafrost on recession processes. An alternative method, namely recession flow analysis, can theoretically be used to derive the active groundwater storage volume to reflect frozen ground degradation in a catchment (Brutsaert and Nieber, 1977;Brutsaert, 2008).…”