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. Despite extreme polar conditions, isolated biological communities are present in valley soils, lakes, and streams and are sensitive to even small changes in climate and environmental conditions. Taylor Valley is the southernmost of three large east-west valleys and it contains three large, closed basins with perennially ice-covered lakes (Lake Bonney, Lake Hoare, and Lake Fryxell). Lake levels are rising (increasing water volume rates ranging from ~140,000 m³/year to ~2,200,000 m³/year) due to an imbalance in ablation (sublimation and evaporation) rates and input of liquid water. We modeled lake-level change in Taylor Valley using current regional climate models to quantify hydrological change. We merged a LiDAR-derived digital elevation model (DEM) of Taylor Valley (2 meter resolution) with a bathymetric grid of each lake (2 meter resolution), resulting in a hydrologically-sound elevation model of the Taylor Valley floor. Volumes were then calculated at one meter elevation intervals to produce a hypsometric curve for each lake basin. From the hypsometric curve, we used past and present measured lake levels and current climate models for Taylor Valley to calculate volumetric rise for each basin. The climate model supports ten-year averages in lake-level rise at a constant rate, accounting for average observed flood years. We then used the hypsometric curve to extrapolate a function which projects yearly water volumes for each basin. The final results allowed us to determine when the basins will merge and spill into the adjacent Ross Sea. Basin spill events have implications on the fragile, isolated biological communities as well as the geologic landscape. The high spatial resolution of the DEM resulted in more accurate calculations of future shoreline locations and water volume than ever previously measured. This study, more generally, shows an application of LiDAR data, bathymetric data, and climate models to understand closed-basin processes in unique climatic environments.