2015 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 , Baptiste, Marisa , Nijssen, Bart , Sun, Ning
Current Investigators: Lettenmaier, Dennis P. , Baptiste, Marisa , Nijssen, Bart , Sun, Ning , Yearsley, John
Institution: University of Washington
EPA Project Officer: Hiscock, Michael
Project Period: June 1, 2012 through May 31, 2016
Project Period Covered by this Report: August 1, 2014 through July 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

Objective:

The objective of this research is to investigate 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 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 one-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 well with available observations.
  • Comparing 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 River 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.

Summary:

  • We extended hydrologic and water quality simulations, using DHSVM-RBM (Sun, et al., 2015), for 15 major partially urbanized watersheds tributary to Puget Sound with different assumptions about future land use and climate change. A publication based on this work is under review for Hydrological Processes (Cao, et al., in review).
  • We successfully integrated DHSVM with adapted water quality modules from SWMM and SWAT. We applied the model, DHSVM-WQ to analyze water quality variations in three urbanized catchments tributary to Lake Washington under current and future conditions with varied land use and climate change scenarios. A publication based on this work will be ready for submission to a peer-reviewed journal shortly (Sun, et al., in preparation).
  • We modified DHSVM-RBM to allow spatially and temporally varying riparian vegetation parameters, and incorporated a reservoir scheme. Through application of the modified DHSVM-RBM on two river basins located in the Connecticut River basin, we examined the effects of spatially and temporally varying riparian buffers and dam-induced hydrologic alterations on water temperature. A publication based on this work is under preparation for submission to a peer-reviewed journal (Yearsley, et al., in preparation).

For the Connecticut River basin as a second test site, we performed hydrologic and water temperature simulations for 14 major sub-basins. 

Future Activities:

We will extend the hydrologic and water temperature simulations to the Connecticut River, and evaluate the hydrologic and stream temperature changes associated with climate change, disturbance of riparian vegetation, and removal of reservoirs and impoundments for the Connecticut River. We will prepare a publication for a peer-reviewed journal based on this work (Sun, et al., in preparation). 


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
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  • Abstract: Wiley-Abstract & Full Text HTML
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  • Other: ResearchGate-Prepublication PDF
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  • 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

     

    The integrated water temperature modeling system is maintained at:

    http://www.hydro.washington.edu/Lettenmaier/Models/RBM/index.shtml Exit

    Progress and Final Reports:

    Original Abstract
    2012 Progress Report
    2013 Progress Report
    2014 Progress Report
    Final Report