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

Abstract

Abstract. Climate warming is changing streamflow regimes and groundwater storage in cold alpine regions. In this study, the Yangbajain headwater catchment in the Lhasa River basin is adopted as the study area to assess streamflow changes and active groundwater storage in response to climate warming. The results show that both annual streamflow and the mean air temperature increase significantly at respective rates of about 12.30 mm per decade and 0.28 ∘C per decade from 1979 to 2013 in the study area. The results of gray relational analysis indicate that the air temperature acts as a primary factor for the increased streamflow. Due to climate warming, the total glacier volume has retreated by over 25 % during the past 50 years, and the areal extent of permafrost has degraded by 15.3 % over the last 20 years. Parallel comparisons with other subbasins in the Lhasa River basin indirectly reveal that the increased streamflow at the Yangbajain Station is mainly fed by the accelerated glacier retreat. Using baseflow recession analysis, we also find that the estimated groundwater storage that is comparable with the GRACE data increases significantly at rates of about 19.32 mm per decade during the abovementioned period. That is to say, as permafrost thaws, more spaces have been made available to accommodate the increasing meltwater. Finally, a large water imbalance (of more than 5.79×107 m3 a−1) between the melt-derived runoff and the actual increase in runoff as well as the groundwater storage is also observed. The results from this study suggest that the impacts of glacial retreat and permafrost degradation show compound behaviors on the storage–discharge mechanism due to climate warming, and that this fundamentally affects the water supply and the mechanisms of streamflow generation and change.

Changes in nonlinearity and stability of streamflow recession characteristics under climate warming in a large glaciated basin of the Tibetan Plateau

“…It has been reported that the permafrost loss in the past decades has enhanced regional groundwater circulation (shortening its timescale) with more discharge to stream flows (Ji et al, 2020;Walvoord et al, 2012). As an example, the baseflow in the source region of the Yangtze River increased at a rate of 1.35 mm a −1 during 1962-2012, following the annual temperature rise of 1.32 • C (Yi et al, 2021) and 1.09 mm a −1 during 1979-2013 in glacierized basins in the TP, with its annual temperature rise of 0.98 • C (Lin et al, 2020). Walvoord and Striegl (2007) found that the groundwater contribution to streamflow in an arctic basin increased by 0.7 %-0.9 % per year from the 1950s to 2005, following its annual temperature rise of 1.24 • C during that period.…”

Can we use precipitation isotope outputs of isotopic general circulation models to improve hydrological modeling in large mountainous catchments on the Tibetan Plateau?

“…The modeling uncertainty is highly related to the model structure and parameters, and our results indicated that the additional information from the isotope data reduced the uncertainty of the parameters. However, global climate changes are changing streamflow regimes on the TP (e.g., M. Lin et al, 2020;Yong et al, 2021), which may re-quest a changing model structure as well. In this study, the model structure was not modified; thus, the changing conditions were far less than adequately represented in the current model, due to lack of adequate understanding of the influence of changing conditions on the runoff generation mechanism.…”

Changes of Nonlinearity and Stability of Streamflow Recession Characteristics under Climate Warming in a Large Glaciated Basin of the Tibetan Plateau

“…As examples, the baseflow in the source region of the Yangtze River increased at a rate of 1.35 mm•a −1 during 1962-2012 following the annual temperature rise of ~1.32 ℃ (Yi et al, 2021), and 1.09 mm•a −1 during 1979-2013 in another glacierized basin of YBJ (Fig. 1), also in the Yangtze River with its annual temperature rise of ~0.98 ℃ (Lin et al, 2020). Walvoord and Striegl (2007) found that the groundwater contribution to streamflow in an arctic basin increased by 0.7-0.9% per year from the 1950s to 2005 following its annual temperature rise of ~1.24 ℃ during that period.…”