Projecting Lake-Level Rise from Airborne LiDAR and Climate Models in Taylor Valley, Antarctica

The McMurdo Dry Valleys (approximately 77°45ˈS, 162°E) is the largest ice-free valley system in Antarctica with a cold, hyper-arid climate and mean valley bottom temperatures ranging from -14.8^oC to -30.0^oC. Despite these extreme polar conditions, common features of these valleys are perennially ice-covered lakes harboring a simple ecosystem that is sensitive to small changes in climate and environmental conditions. Taylor Valley is the southernmost of three large east-west valleys and it contains three closed basins with perennially ice-covered lakes (Lake Bonney, Lake Hoare, and Lake Fryxell). Over the past century, the lake levels have been rising due to an imbalance in ablation (sublimation and evaporation) rates and input of liquid water. If the trends continue, the lakes will merge, which will lead to increased turbidity and potential changes in unique biochemical stratifications of those lakes. Here, we present a lake-level rise model for the Taylor Valley, which predicts timing and order of merging lakes under various inflow rate scenarios by constructing the best hypsometric data of the valley. We have generated a hydrologically useful elevation model of the Taylor Valley by combining a LiDAR-derived digital elevation model (2 meter resolution) with a bathymetric grid of each lake (2 meter resolution). Water volumes were then calculated at ten-centimeter elevation intervals to produce a hypsometric curve for each lake basin. The hypsometric curve was used to derive a function, which projects yearly water volumes for each basin. Our model allows the user to input annual volumetric change for each basin to predict shoreline migration and year of a possible spill event. The output allows users to determine when the basins will merge and spill into the adjacent Ross Sea using multiple simulations visually. Basin spill events have implications on the fragile and isolated biological communities as well as the geologic landscape. A web application was developed to prompt input values and display water volume and surface area changes over time spatially and numerically. The high spatial resolution of the DEM resulted in more accurate calculations of future shoreline migration and water volume than ever previously measured. This study, more generally, shows an application of LiDAR data and bathymetric data, to understand hydrological closed-basin processes in unique climatic environments.