2013 Progress Report: Prediction of Effects of Changing Precipitation Extremes on Urban Water Quality

EPA Grant Number: R835195
Title: Prediction of Effects of Changing Precipitation Extremes on Urban Water Quality
Investigators: Yearsley, John , Nijssen, Bart , Baptiste, Marisa , Sun, Ning , Cao, Qian
Current Investigators: Lettenmaier, Dennis P. , Nijssen, Bart , Yearsley, John , Baptiste, Marisa , Sun, Ning
Institution: University of Washington
EPA Project Officer: Packard, Benjamin H
Project Period: June 1, 2012 through May 31, 2016
Project Period Covered by this Report: June 1, 2013 through August 20,2014
Project Amount: $699,905
RFA: Extreme Event Impacts on Air Quality and Water Quality with a Changing Global Climate (2011) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Global Climate Change , Water and Watersheds , Climate Change , Air , Water


To study the impacts of extreme precipitation on urban water quality. 

Progress Summary:

We extended hydrologic simulations for three additional small urban tributary watersheds to Lake Washington and 15 major partially urbanized tributary watersheds to Puget Sound.

For the Connecticut River basin as a second test site, we acquired streamflow and water quality monitoring data, and prepared all model input data for hydrologic simulations.

We successfully integrated DHSVM with RBM. We applied this combined model (DHSVM-RBM) to analyze the effects of land cover and riparian vegetation on stream temperature. The resulting paper describing this research now is in review (Sun, et al., in review). Using the same modeling system, we also have completed an analysis of the stream temperature for the 15 major basin tributaries to Puget Sound using present land cover. A publication based on this work is in preparation for submittal to a peer-reviewed journal (Cao, et al., in preparation).

We continue to develop the version of DHSVM that includes the SWMM water quality module and further adapted the process-based nutrient modules in the Soil and Water Assessment Tool (SWAT) to the modeling system. We have applied DHSVM-WQ to four small urbanized basins that are important tributaries to Lake Washington.

We have begun developing climate scenarios for extreme precipitation events developed from the U.S. CMIP5 integrated scenarios. 


Key Findings:

The hydrologic model DHSVM, coupled with the stream temperature model RBM, is able to represent observed historic streamflow and stream temperature variations at sub-daily time scales and at high spatial resolutions on the order of 100 m for watersheds of up to 100 km2.

The application of DHSVM-RBM to a small urban watershed indicates that loss of riparian vegetation plays an important role in modulating water temperatures, in particular annual maximum temperature, which could be mostly reversed by restoring riparian vegetation in a fairly narrow corridor – a finding that has important implications for management of the riparian corridor.

Thermal loading to Puget Sound varies from season to season, increasing in fall and winter and decreasing in spring and summer compared with the long-term base temperature. The estimated annual thermal load is around 2791 cms·K, accounted for mostly by the Skagit and Snohomish Rivers.

The integrated DHSVM and adapted water quality modules from SWMM and SWAT provide reasonable predictions of total suspended solids, coliform bacteria and total phosphorous in small urbanized watersheds at sub-daily time scales. 

Future Activities:

The key activities for the next period of this project are the deployment and analysis of the survey instruments. The surveys should be deployed in fall 2014, with analysis of survey results in early 2015. Analysis of survey results then will inform selection of agencies to follow-up with for in-depth case study analysis. These case studies will be underway by summer 2015. We will present preliminary findings, including survey design at the American Geophysical Union meeting in December 2014. 

Extend the scope of the study from the Mercer Creek watershed to include the entire Puget Sound Basin and the Connecticut River. 

Apply downscaled climate scenarios for purposes of analyzing extreme events under climate change in selected basins of Puget Sound and the Connecticut River. 

Conduct further testing of the water quality module of DHSVM and the stream temperature model. 

Continue to work towards the goals described in the proposal.  Respond to interest in our work from marine scientists and generate simulations compatible with goals expressed in our proposal.  The results provide estimates of thermal inputs to Puget Sound. 

Journal Articles on this Report : 1 Displayed | Download in RIS Format

Other project views: All 8 publications 3 publications in selected types All 3 journal articles
Type Citation Project Document Sources
Journal Article Sun N, Yearsley J, Voisin N, Lettenmaier DP. A spatially distributed model for the assessment of land use impacts on stream temperature in small urban watersheds. Hydrological Processes 2015;29(10):2331-2345. R835195 (2013)
R835195 (2014)
R835195 (2015)
R835195 (Final)
  • Full-text: Wiley-Full Text PDF
  • Abstract: Wiley-Abstract & Full Text HTML
  • Other: ResearchGate-Prepublication PDF
  • Relevant Websites:

    A repository for the source code and tutorial for model development of DSHVM is at: http://www.hydro.washington.edu/Lettenmaier/Models/DHSVM/index.shtml Exit Exit

    The integrated water temperature modeling system is maintained at: http://www.hydro.washington.edu/Lettenmaier/Models/RBM/index.shtml Exit Exit

    Progress and Final Reports:

    Original Abstract
  • 2012 Progress Report
  • 2014 Progress Report
  • 2015 Progress Report
  • Final Report