Hydrological Connectivity of the Landscape of the McMurdo Dry Valleys, Antarctica

The McMurdo Dry Valleys (MDV) of Antarctica are composed of nearly 2000 km of ice-free terrain, supporting a vibrant cold desert ecosystem despite harsh conditions. The ecosystem is largely regulated by the hydrologic cycle within the MDV, which is controlled by climate dynamics. The strength and timing of connections among the hydrologic reservoirs of the MDV (atmosphere, glaciers, soils and permafrost, streams and their hyporheic zones, and lakes) are dependent upon daily, seasonal, and annual surface energy balance. For example, glacier melt occurs during short periods in the summer, providing stream flow to closed-basin lakes. Similarly, the magnitude of sublimation of snow on valley floors and perennial ice covers on lakes is a function of wind, temperature, radiation, and atmospheric water content (humidity). Here, we describe these reservoirs and connections across the landscape to provide an overview of our current understanding of the system, as it is poised to change in response to changing climate in the coming decades. Measurement of hydrologic fluxes and states of hydrologic reservoirs in the MDV provides both a context for quantifying responses to climate change and a careful characterization of the potential direct drivers of ecosystem response. The MDV also provide a unique real-world laboratory in which to study fundamental hydrologic processes (with the exception of rainfall).