Abstract
Abstract. The Tibetan Plateau (TP), known as Asia's water tower, is quite sensitive to climate change, which is reflected by changes in hydrologic state variables such as lake water storage. Given the extremely limited ground observations on the TP due to the harsh environment and complex terrain, we exploited multiple altimetric missions and Landsat satellite data to create high-temporal-resolution lake water level and storage change time series at weekly to monthly timescales for 52 large lakes (50 lakes larger than 150 km2 and 2 lakes larger than 100 km2) on the TP during 2000–2017. The data sets are available online at https://doi.org/10.1594/PANGAEA.898411 (Li et al., 2019). With Landsat archives and altimetry data, we developed water levels from lake shoreline positions (i.e., Landsat-derived water levels) that cover the study period and serve as an ideal reference for merging multisource lake water levels with systematic biases being removed. To validate the Landsat-derived water levels, field experiments were carried out in two typical lakes, and theoretical uncertainty analysis was performed based on high-resolution optical images (0.8 m) as well. The RMSE of the Landsat-derived water levels is 0.11 m compared with the in situ measurements, consistent with the magnitude from theoretical analysis (0.1–0.2 m). The accuracy of the Landsat-derived water levels that can be derived in relatively small lakes is comparable with most altimetry data. The resulting merged Landsat-derived and altimetric lake water levels can provide accurate information on multiyear and short-term monitoring of lake water levels and storage changes on the TP, and critical information on lake overflow flood monitoring and prediction as the expansion of some TP lakes becomes a serious threat to surrounding residents and infrastructure.
Highlights
The Tibetan Plateau (TP), providing vital water resources for more than a billion population in Asia, is a sensitive region undergoing rapid climate change (Field et al, 2014)
Wang et al (2018) showed that global endorheic basins are experiencing a decline in water storage, whereas the endorheic basin on the TP is an exception
The uncertainty quantification of the Landsatderived water levels developed in this study indicates clearly that the accuracy of Landsat-derived water levels depends on the width of an region of interest (ROI), e.g., the number of pixels/observations, slope of the lake shore, the effectiveness of the water classification method, and the uncertainty in the altimetry water level used for regression
Summary
The Tibetan Plateau (TP), providing vital water resources for more than a billion population in Asia, is a sensitive region undergoing rapid climate change (Field et al, 2014). With little disturbance by human activity in this area, lake storage changes may serve as an important indicator that reflects changes in regional hydrologic processes and responses to climate change. Given the fact that TP lakes have been expanding for more than 20 years (Pekel et al, 2016), quality data sets on lake water level and/or storage could be the basis for investigating its causes (e.g., climate change/variability) and interactions with the water/energy cycles and human society (e.g., increasing risks of inundation and overflow floods)
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