The role of snowmelt, glacier melt and rainfall in streamflow dynamics on James Ross Island, Antarctic Peninsula

Abstract

The Antarctic Peninsula is experiencing a rapid increase in air temperature, which has a major impact on the entire ecosystem, including the runoff process. Understanding the water balance dynamics in such a fragile and sensitive environment is therefore crucial. Although water availability plays an important role in polar ecosystems, runoff generation in the Antarctic Peninsula region is still poorly understood. We analysed the variability in rain, snow and glacier contributions to runoff in relation to climate variability in a small, partly glaciated catchment on James Ross Island in the north-eastern Antarctic Peninsula. We used the hydrological model HBV to simulate the runoff process from June 2010 to May 2021 at a daily resolution. The model was calibrated against both measured discharge and glacier mass balance. Model simulations showed the negative mass balance of Triangular Glacier for 9 out of 11 study years, with an average annual mass loss of 49 mm water equivalent. About 92 % of the annual runoff occurred between October and May. On average, peak runoff occurred in the second half of the summer season due to the combination of glacier melt and snowmelt. The majority (76 %) of runoff originated from snowmelt, 14 % originated from glacier melt and 10 % from rainfall. Higher total annual runoff occurred in warmer and drier years associated with high glacier melt runoff. The contribution of snowmelt to total runoff was higher in colder years with more precipitation. Our simulation showed the presence of significant runoff-generating events outside the usual high summer runoff measurement season.