Impacts of Climate Change in Snowmelt-Dominated Alpine Catchments: Development and Assessment of Comparative Methods to Quantify the Role of Dynamic Storage and Subsurface Hydrologic Processes

摘要

Snowmelt-dominated systems are a significant source of water supply for the Western United States. Changes in timing and duration of snowmelt are predicted to continue under climate change; however, the impact this change will have on water resources is not well understood. The ability to compare hydrologic processes across space and time is critical to accurately assess the physical and chemical response of headwater systems to climate change. This dissertation builds upon previous work by using long-term data from two snowmelt dominated catchments to investigate the response of hydrologic processes at different temporal and spatial scales. First, results from an hourly spatially-distributed energy balance snowmelt model were spatially and temporally aggregated to provide daily, catchment-wide snowmelt estimates, which, along with measured discharge and hydrochemical data were used to assess and compare hydrologic processes which occur on an annual scale in two headwater catchments for an eleven year study period. Second, the magnitude and timing of snowmelt, discharge fluxes and hydrochemical data were used to assess and compare inter-annual catchment response in two headwater catchments for an eleven year study period. Third, a pseudoinverse method was developed to compare mineral weathering fluxes in a series of nested sub-catchments over an eleven year study period. Advances from this work include the use of an independently-created energy balance snowmelt model for spatially-distributed hydrologic input for catchment-scale water balance, application of a quantifiable measure of catchment-scale hydrologic flux hysteresis and the development of a method to quantify and compare mineral weathering reactions between source waters across space and time. These methods were utilized to quantify and assess its role of dynamic storage in mitigating climate change response.