Grantee Research Project Results
2011 Progress Report: Assessing the Impact of a Warmer Climate on Stream Water Quality Across theMountainous Western United States.
EPA Grant Number: R834191Title: Assessing the Impact of a Warmer Climate on Stream Water Quality Across theMountainous Western United States.
Investigators: Stewart-Frey, Iris , Maurer, Edwin
Institution: Santa Clara University
EPA Project Officer: Packard, Benjamin H
Project Period: September 1, 2009 through August 31, 2012 (Extended to August 31, 2013)
Project Period Covered by this Report: September 1, 2010 through August 31,2011
Project Amount: $250,000
RFA: Consequences of Global Change for Water Quality (2008) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Climate Change , Watersheds , Aquatic Ecosystems , Water
Objective:
As the water supply in the West hinges on snowmelt storage, it is particularly sensitive to the warmer temperatures expected from anthropogenically driven global change. While many studies have evaluated changes in the quantity and timing of the near-surface water cycle, the impact of projected climatic changes on infiltration, soil moisture, sediment transport, subsurface drainage, flow processes, and especially water quality from the sub-watershed to the regional scale have not systematically been explored. An assessment of these impacts is especially critical in the western United States and particularly California, where current and projected future demands on fresh water resources are high. Thus, the objective for our work is to assess the impact of projected climatic changes on the near-surface hydrology and water quality across the mountainous western United States, using the Sierra Nevada as a pilot.
Progress Summary:
To address the research objectives, we are using a modeling approach that couples General Circulation Models (GCMs) output to an established hydrological model (SWAT). To date, we have prepared and used the downscaled GCM output for an ensemble of 16 different GCMs and 2 emission scenarios. Further, we have developed a stream temperature model that reflects the combined influence of meteorological (air temperature) and hydrological conditions (streamflow, snowmelt, groundwater, surface runoff, and lateral soil flow) on stream water temperature within a watershed. This new model improves the current approach of using a linear air-stream temperature relationship and was found to improve representation of observed daily stream temperature, especially with capturing stream temperature changes resulting from changes in hydro-climatological conditions. As stream temperature is the basis for modeling various in-stream biological and water quality processes in SWAT, the new model greatly improves prediction accuracy for these processes. For Sierra Nevada (CA) and Colorado River watersheds, SWAT with the new stream temperature model was successfully calibrated and validated. Subsequently, near-surface hydrologic flows and stream water quality (stream temperature, dissolved oxygen [DO], sediment transport) have been modeled on the sub-basin scale. Model results suggest earlier runoff timing with impacts not only on streamflow, but also evapotranspiration, soil storage, surface, and subsurface flows, such that less water is available in spring and summer, thus potentially impacting not only aquatic, but also terrestrial ecosystems. In addition, stream temperature is likely to increase by several degrees during spring and summer, with large concurrent decreases in DO, which are highly likely to impact stream ecosystems. The watersheds most sensitive to climatic change impacts were identified, and could aid ecosystems management at the sub-basin scale. A similar approach is being taken for watersheds throughout the West. Results and impacts are evaluated with the ensemble of GCMs, two emission scenarios, different temporal and spatial scales, and from region to region.
Future Activities:
For the upcoming reporting period, we are planning to complete the sensitivity analysis, calibration and validation phases as well as all water flow and quality simulations for the entire western United States using the SWAT and new stream temperature models. We also are planning to prepare at least three more publications related to this work.
Journal Articles on this Report : 3 Displayed | Download in RIS Format
Other project views: | All 26 publications | 10 publications in selected types | All 10 journal articles |
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Ficklin DL, Stewart IT, Maurer EP. Projections of 21st century Sierra Nevada local hydrologic flow components using an ensemble of General Circulation Models. Journal of the American Water Resources Association 2012;48(6):1104-1125. |
R834191 (2011) R834191 (2012) R834191 (Final) |
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Ficklin DL, Luo Y, Stewart IT, Maurer EP. Development and application of a hydroclimatological stream temperature model within the Soil and Water Assessment Tool. Water Resources Research 2012;48:W01511. |
R834191 (2011) R834191 (2012) R834191 (Final) |
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Ficklin DL, Stewart IT, Maurer EP. Effects of projected climate change on the hydrology in the Mono Lake Basin, California. Climatic Change 2013;116(1):111-131. |
R834191 (2011) R834191 (2012) R834191 (Final) |
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Supplemental Keywords:
climate change, streamflow, streamflow timing, stream temperature, water quality, western United States, hydrology, SWAT, stream temperature model, RFA, Air, climate change, Air Pollution Effects, Atmosphere, environmental monitoring, water resources, climate modelsProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.