Matt Miller is a Research Hydrologist with the U.S. Geological Survey Earth Systems Modeling Branch of the Integrated Modeling and Prediction Division听in Boulder, Colorado.听听His current research focuses on developing new approaches for interpreting large data sets to quantify the relationships between water quality, hydrology, land use, and climate at watershed, regional, and national scales.听 Matt has worked extensively in the Colorado River Basin, Chesapeake Bay Watershed, and in Brazilian watersheds on topics related to understanding the role of groundwater in sustaining surface water flow, quantifying sources and transport of nutrients and dissolved solids, and forecasting baseflow, streamflow, and nutrient loading in response to changes in climate.听 Matt is currently the project manager for the Integrated Water Availability Assessments (IWAAs) Upper Colorado River Basin project.听 Matt and his team are working to develop an approach to provide regionally specific estimates, understanding, and forecasts of the regional water budget and controls on water availability in the Upper Colorado River Basin.
Abstract
Projected large-scale regional baseflow declines in response to changing climate in the Upper Colorado River Basin
Given the importance of groundwater in sustaining Upper Colorado River Basin (UCRB) streamflow (over 50% of streamflow originates as baseflow), effective management of water resources in the basin requires estimates of how baseflow may change under projected climatic changes.听 We applied projections of future climate to a calibrated hybrid statistical-deterministic model (SPAtially Referenced Regressions On Watershed attributes, SPARROW) to estimate future baseflow changes under warm/wet, hot/dry, and central tendency climatic conditions for thirty-year periods centered around 2030, 2050, and 2080 compared to the historical period (1984-2012).听 Projected widespread baseflow declines, regardless of changes in precipitation, suggest increased evapotranspiration reduced baseflow.听 The largest relative declines in baseflow are projected to occur in high elevation source areas, and baseflow delivered to the UCRB outlet declining by between 11% and 40%.听 Results have implications for human and ecological water availability in one of the most heavily managed watersheds in the world.