Contrasting hydrological and thermal intensities determine seasonal lake-level variations – a case study at Paiku Co on the southern Tibetan Plateau

Lei, Yajie; Yang, Kun; La, Zhu; Ma, Yaoming; Bird, Broxton W.

doi:10.5194/hess-25-3163-2021

Cited by 16 publications

(14 citation statements)

References 55 publications

(73 reference statements)

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“…Lake evaporation does not exhibit a linear trend of increase or decrease and is mostly dominated by year to year variability. Though slightly lower, our evaporation results are in agreement with the values fromLei et al (2021), which are derived from local and regional meteorological…”

supporting

confidence: 91%

“…Regarding the simulated temperature fields, the comparison with the loggers bring confidence that the model captures both the surface temperature mean values and seasonal patterns, but the validation exercise would benefit from additional loggers located throughout the catchment and ideally also temperature profiles from boreholes. Similarly, even though the lake evaporation values we compute finds a good agreement with those from Lei et al (2021), a longer comparison would have brought a higher level of confidence in the values.…”

Section: Data Scarcitymentioning

confidence: 57%

“…At the seasonal scale, the lake level cycle has an amplitude of ~ 0.4 m. It is marked by a strong increase during the monsoon period (JJAS) supported by direct precipitation, glacier melt and land runoff. From October and until the next monsoon period, evaporation dominates the lake mass budget and the level decreases rapidly until January and at a slower rate afterwards (Lei et al, 2021).…”

Section: /45mentioning

confidence: 99%

“…5, C). We used the simulated evaporation together with the lake level data and lake area data from Lei et al (2018) and Lei et al (2021) and the precipitation forcing datasets (3.2.2) to derive the total runoff (land + glacier) required as an input to the lake budget to reproduce the lake variations. This required runoff corresponds to the red line of Fig.…”

Section: /45mentioning

confidence: 99%

“…A and B: modeled mean daily ground surface temperatures compared to measured ground surface temperatures for logger 15 and logger 13 (location on Fig.1). C: modeled yearly lake evaporation (blue curve) and comparison with values calculated byLei et al (2021) in the light blue zone. The grey curve shows the smoothed lake level variations based on observations fromLei et al (2018) (grey points) and Lei et al (2021) (grey oscillating line).…”

mentioning

confidence: 99%

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Recent ground thermo-hydrological changes in a Tibetan endorheic catchment and implications for lake level changes

Martin

Westermann

Magni

et al. 2022

Preprint

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Abstract. Climate change modifies the water and energy fluxes between the atmosphere and the surface in mountainous regions. This is particularly true over the Qinghai-Tibet Plateau (QTP), a major headwater region of the world, which has shown substantial hydrological changes over the last decades. Among them, the rapid lake level variations observed throughout the plateau remain puzzling and much is still to be understood regarding the spatial distribution of lake level trends (increase/decrease) and paces. The ground across the QTP hosts either permafrost or seasonally frozen ground and both are affected by climate change. In this environment, the ground thermal regime influences liquid water availability, evaporation and runoff. Therefore, climate-driven modifications of the ground thermal regime may contribute to lake level variations. For now, this hypothesis has been overlooked by modelers because of the scarcity of field data and the difficulty to account for the spatial variability of the climate and its influence on the ground thermo-hydrological regime in a numerical framework. This study focuses on the cryo-hydrology of the catchment of Lake Paiku (Southern Tibet) for the 1980–2019 period. We use TopoSCALE and TopoSUB to downscale ERA5 data and capture the spatial variability of the climate in our forcing data. We use a distributed setup of the CryoGrid community model (version 1.0) to quantify thermo-hydrological changes in the ground during the period. Forcing data and simulation outputs are validated with weather station data, surface temperature logger data and the lake level variations. We show that both seasonal frozen ground and permafrost have warmed (1.7 °C per century 2 m deep), increasing the availability of liquid water in the ground and the duration of seasonal thaw. Both phenomena promote evaporation and runoff but ground warming drives a strong increase in subsurface runoff, so that the runoff/(evaporation + runoff) ratio increases over time. Summer evaporation is an important energy sink and we find active layer deepening only where evaporation is limited. The presence of permafrost is found to promote evaporation at the expense of runoff, consistent with recent studies. Yet, this relationship seems to be climate dependent and we show that a colder and wetter climate produces the opposite effect. This ambivalent influence of permafrost may help to understand the contrasting lake level variations observed between the south and north of the QTP, opening new perspectives for future investigations.

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supporting

confidence: 91%

Section: Data Scarcitymentioning

confidence: 57%

Section: /45mentioning

confidence: 99%

Section: /45mentioning

confidence: 99%

mentioning

confidence: 99%

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