Climate change, extreme weather, land-use change, and other perturbations are significantly reshaping interactions among the vegetation, soil, fluvial, and subsurface compartments of watersheds throughout the world. Watersheds are recognized as Earth’s key functional unit for managing water resources, but their hydrological interactions also mediate biogeochemical processes that support all terrestrial life. These complex interactions, which occur within a heterogeneous landscape can lead to a cascade of effects on downstream water availability, nutrient and metal loading, and carbon cycling. Despite significant implications for energy production, agriculture, water quality, and other societal benefits important to U.S. Department of Energy (DOE) energy and environmental missions, uncertainty associated with predicting watershed function and dynamics remains high.
To address this uncertainty, the Watershed Function Scientific Focus Area (SFA) is developing a predictive understanding of how mountainous watersheds retain and release water, nutrients, carbon, and metals. In particular, the SFA is developing understanding and tools to measure and predict how droughts, early snowmelt, and other perturbations impact downstream water availability and biogeochemical cycling at episodic to decadal timescales.
Using a scale-adaptive approach, the SFA posits that the integrated watershed response to disturbance events can be adequately predicted through consideration of interactions and feedbacks occurring within a limited number of subsystems. Scale-Adaptive Watershed Simulation Capabilities (SAWaSC) are used to simulate the aggregated watershed response to perturbations (floods, droughts, and early snowmelt) through adaptive mesh refinement methods that can telescope into subsystems or other small parts of the watershed—only where and when needed.