Linking ground ice and glacier melting to lake volume change in the Dogai Coring watershed on the Tibetan Plateau

Abstract

The Dogai Coring Lake on the Tibetan Plateau, with widespread permafrost and glaciers in the watershed, has expanded rapidly between 2014 and 2020. However, it remains unclear how much melting water from permafrost and glaciers contributes to the increase in lake volume. This study quantifies the potential amount of water released by the melt of permafrost and glaciers, and assesses the fraction of water storage gains in the lake offset by the loss from the cryosphere (i.e., ground ice and glaciers). The small baseline subset interferometric synthetic aperture radar (SBAS-InSAR) method was used to derive the spatiotemporal changes in surface deformation, which then assisted the estimation of the potential water release from ground ice melting. The glacier mass balance was estimated using a geodetic method with ASTER DEMs. Results show that 51.3 % of the region experienced subsidence with rates in the range of 5–20 mm∙a−1 during 2014–2020. Ground ice melting released water at a rate of 35.1 × 106 m3∙a−1, accounting for ∼19.3 % of the increase in lake volume. The glacier mass loss rate was estimated to be − 0.69 ± 0.04 m w.e. yr−1 (113.6 ± 7.3 × 106 m3∙a−1), contributing ∼62.5 % to the lake volume increase. Our results show that the water storage loss in the cryosphere has largely (∼80 %) offset the water storage gain in the lake, suggesting that cryospheric meltwater is an important factor regulating water budget change of the lake watershed.