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Center for Nonlinear Studies |
At regional scales, spatial variation in eco-hydrologic processes is a complex function of geology, soil, topography, climate and vegetation patterns. Understanding how these different controls vary and interact remains a key challenge for climate change impact assessment. In snow-dominated mountain environments, there is growing evidence that reduced snow accumulation and earlier melt is already occurring and is an important driver of summer streamflow and ecosystem responses. Modeling these responses requires estimation not only of the spatial pattern of melt response to warming and local atmospheric drivers, but also the convolution of these spatial patterns with vegetation water use and subsurface drainage. We use a coupled process-based model of ecosystem hydrologic and carbon cycling, RHESSys, to demonstrate that soil moisture drainage and storage characteristics exert a significant control on how forest water use, and streamflow respond to earlier snowmelt. We focus our modeling scenarios on sites with measurements of streamflow, and vegetation growth that can be used to evaluate model performance. We also discuss representation of fine-scale (within 1km) patterns of energy and moisture inputs and demonstrate the limitations of standard assumptions often used in hydrologic models to distribute air temperature and moisture at these scales. We discuss how emerging combinations of measurements and modeling studies can provide new insights into these interactions and resulting landscape-level sensitivities to climate warming for both ecosystem and human water users.
Host: COSIM, Todd Ringler,ringler@lanl.gov