2014 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: Lettenmaier, Dennis P. , Yearsley, John
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, 2014 through May 31,2015
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


The objectives of this project are to determine the impacts of extreme precipitation on urban water quality.

Progress Summary:

We configured the coupled hydrologic model DHSVM and stream temperature RBM (DHSVM-RBM) for 15 major sub-basins in the Puget Sound basin to represent observed historic streamflow and stream temperature variations at sub-daily time scales and 150 m spatial resolutions. We examined the hydrology and water temperature responses in the 15 basins to different assumptions about future land use and climate change, and explored the contribution of riverine thermal loadings to the heat balance of Puget Sound.

  • DHSVM-RBM is able to produce streamflow and stream temperature predictions that mostly match available observations well.
  • The riparian vegetation has a much greater effect on stream temperatures than does basin-wide land cover change, especially during summer low flow periods when maximum stream temperatures occur; and the effect of riparian vegetation on stream temperatures is comparable with that of climate change in summer months. Hence, the restoration of riparian vegetation over a fairly narrow streamside corridor can mitigate some (over half in some cases) of the effects of future climate change in summer low flow periods.
  • The riverine thermal loadings account for up to 1/8 of the overall thermal inputs to Puget Sound in winter, and this fraction increases with both urbanization and climate change, although the increase is relatively modest in both cases. The fraction in summer, however, will decrease with climate change.

We developed a grid-based spatially distributed hydrology and water quality model, DHSVM-WQ, for nonpoint-source water quality simulations in urbanized watersheds at a high spatial and temporal resolution. We configured DHSVM-WQ for three partially urbanized catchments to evaluate the water quality responses to climate and land use change scenarios.

  • DHSVM-WQ provides plausible predictions of streamflow, total suspended solids (TSS), total phosphorous (TP) and water temperature that agree with available observations well.
  • Compared to the climate change scenarios, the land use change (i.e., urbanization) scenario has a much greater impact on TSS and TP loading in both magnitude and seasonal variability. The thermal loading from streams to the receiving lake, on the other hand, is more sensitive to the air temperature warming scenarios. The combined urbanization and climate change scenario yields significantly higher streamflow, TSS and TP loading, and thermal input to the lake particularly in winter.

We investigated the implications of spatially and temporally varying riparian buffers and dam-induced hydrologic alterations on water temperature, with modified DHSVM-RBM, in two river basins located in the Connecticut River basin, the Ottauquechee and White River. We compared water temperature simulations under scenarios associated with removal of riparian vegetation and existing impoundments.

  • The modified DHSVM-RBM, which allows spatially and temporally varying riparian vegetation parameters, is able to produce the water temperature predictions that agree well with gage observations along the channel longitudinal profile. The reservoir scheme in RBM is able to represent the impact of reservoirs on downstream water temperature comparable to gage observations.
  • There are significant impacts to water temperatures due to alterations in flow and modification of riparian buffers.

Journal Articles on this Report : 2 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
  • Journal Article Sun N, Yearsley J, Baptiste M, Cao Q, Lettenmaier DP, Nijssen B. A spatially distributed model for assessment of the effects of changing land use and climate on urban stream quality. Hydrological Processes 2016;30(25):4779-4798. R835195 (2014)
    R835195 (Final)
  • Full-text: Wiley-Full Text PDF
  • Abstract: Wiley-Abstract & Full Text HTML
  • Other: ResearchGate-Abstract & Full Text PDF
  • Supplemental Keywords:

    Urban water quality, climate downscaling, hydrologic impacts of climate change

    Relevant Websites:

    A repository for the source code and tutorial for model development of DSHVM is at:  PNNL: Distributed Hydrology Soil Vegetation Model (DHSVM)

    The integrated water temperature modeling system is maintained at:  RBM Semi-Lagrangian Stream Temperature Model | University of Washington Exit

    Progress and Final Reports:

    Original Abstract
  • 2012 Progress Report
  • 2013 Progress Report
  • 2015 Progress Report
  • Final Report