Grantee Research Project Results
2010 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, 2009 through August 31,2010
Project Amount: $250,000
RFA: Consequences of Global Change for Water Quality (2008) RFA Text | Recipients Lists
Research Category: Aquatic Ecosystems , Ecological Indicators/Assessment/Restoration , Watersheds , Water , Climate Change
Objective:
As the water supply in the West hinges on the snowmelt storage, it is particularly sensitive to warming temperatures . It has therefore been noted with considerable concern that climatic changes due to anthropogenic greenhouse gas emissions are already impacting the water resources in the western United States today. During the latter part of the 20th century (1979-2005), annual, and especially winter temperatures have increased by about 1 °C per decade over North America. In general, a lot more focus has been placed on evaluating changes in the quantity and timing of the near-surface water cycle, than its impact on water and little is known about the impact of the projected climatic changes on the infiltration, soilerosion and subsurface drainage and flow processes beyond the watershed scale. An assessment of these impacts is especially critical in the western U.S. and particularly California, where current and projected future demands on fresh water resources are high. To date, climate change impacts on water quantity and quality, and their effect on aquatic ecosystems in the West has not been systematically explored on the regional scale. Thus, the overall objective for the proposed work is to assess the impact of projected climatic changes on the near-surface hydrology (streamflow, shallow groundwater recharge) and water quality across the mountainous western United States. To this end, we are developing a modeling protocol that couples future climate data for different scenarios with an established hydrologic model to simulate streamflow and water quality across the western U.S. mountain ranges. This approach allows us to compare the differences in impact on water quantity and quality for the ensemble of GCMs, 2 SERES scenarios, different temporal and spatial scales, and from region to region, as well as evaluate the impact of projected water quantity and quality changes on aquatic ecosystems. Our hypothesis is that throughout the mountainous western United States, climatic changes projected through the end of the century are likely to impact the near-surface hydrologic response, including water quality, such that water supply and aquatic ecosystems are significantly affected.Progress Summary:
To address the research objectives, we are using a modeling approach that couples output from 16 different GCMs and two emission scenarios to an established hydrological model capable of treating snowmelt, runoff, near-surface groundwater flow, and water quality on the regional scale. The hydrological model selected is the Soil and Water Assessment Tool (SWAT) with an improved snowmelt routine for mountainous terrain. Our approach is to apply the modeling protocol to the Sierra Nevada mountain range on the subbasin scale and validate the results through comparison of results from other modeling efforts.Subsequently, we are using the setup to model the western United States mountain regions on the basin scale and to compare the differences in impact on water quantity and quality for the ensemble of GCMs, 3 SERES scenarios, different temporal and spatial scales, and from region to region. Finally, we will be evaluating the impact of projected water quantity and quality changes on aquatic ecosystems in the study area. Currently, we are 6 months into the project and have prepared the SWAT input layers for the Sierra Nevada, as well as historic climate data for the entire western United States. We have also successfully set up the model for the Sierra Nevada and Colorado Basin watersheds, as well as prepared the daily GCM data input. Currently, the Sierra Nevada and the Colorado River watersheds are being calibrated for streamflow, temperature, sediment, and dissolved oxygen.
Future Activities:
For the upcoming reporting period, we are planning to complete the sensitivity analysis, calibration, and validation phases as well as the simulations for both the Sierra Nevada and the wider western United States using the SWAT model.Journal Articles:
No journal articles submitted with this report: View all 26 publications for this projectSupplemental Keywords:
climate change, streamflow timing, water quality, western U.S., hydrology, RFA, Air, Atmosphere, Air Pollution Effects, climate change, water quality, environmental monitoring, climate modelsRelevant Websites:
Not yet established.Progress 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.