Grantee Research Project Results
2011 Progress Report: Consequences of Global Climate and Emissions Changes on U.S. Water Quality: An Integrated Modeling Assessment
EPA Grant Number: R834189Title: Consequences of Global Climate and Emissions Changes on U.S. Water Quality: An Integrated Modeling Assessment
Investigators: Liang, Xin-Zhong , Wuebbles, Donald J. , Arnold, Jeff , Tuppad, Pushpa , Srinivasan, Raghavan , He, Yuxiang
Current Investigators: Liang, Xin-Zhong , Wuebbles, Donald J. , Srinivasan, Raghavan , Tuppad, Pushpa , Arnold, Jeff
Institution: University of Maryland - College Park
EPA Project Officer: Packard, Benjamin H
Project Period: August 1, 2009 through July 31, 2012 (Extended to July 31, 2014)
Project Period Covered by this Report: August 1, 2010 through July 31,2011
Project Amount: $723,559
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:
The objective of the ISWS/UIUC/UMD project is to quantify and better understand the impacts and uncertainties of global climate and emission changes from the present to 2050 on U.S. water quality, focusing on the nitrogen cycle and accounting for potential agricultural land conversion to alternative food and biofuel crops, to enable decision makers to design effective management plans and regional adaptive strategies to reduce the risk of harmful impacts. A state-of-the-art modeling system is used to quantify the impacts on future U.S. water quality by a suite of climate changes projected from the present to 2050, including mean and variability (especially extremes). The system integrates climate dynamics, atmospheric physics and chemistry, terrestrial hydrology, agroecology and biogeochemistry, surface emissions, and their nonlinear interactions across a full range of spatial and temporal scales. It consists of two general circulation models (GCMs), with low (National Center for Atmospheric Research – NCAR) and high (Geophysical Fluid Dynamics Laboratory – GFDL) climate sensitivity, and NCAR community atmosphere model coupled with the model for ozone and related chemical tracers (MOZART) chemistry (CAM-Chem) to project global changes in climate and chemical transport under three Intergovernmental Panel on Climate Change (IPCC) special report on emissions scenarios (SRES) (low, medium, high) accounting for dynamic land use changes; they represent the likely range of future projections of climatic and chemical lateral boundary conditions (LBCs) that force ISWS climate extension of the weather research and forecasting model (CWRF) and Environmental Protection Agency (EPA) community multiscale air quality model (CMAQ) to downscale regional climate and air quality in North America; these then provide climatic and hydrologic conditions and atmospheric NO3- and NH4+ depositions that drive the soil and water assessment tool (SWAT) to predict water quantity and quality over the entire continental United States. Such a predictive SWAT (PSWAT) incorporates the most comprehensive pollutant sources (natural and anthropogenic, point and nonpoint), surface and subsurface watershed processes (upland, soil, plant and crop, channel and flood plain, urban, lake and reservoir), agricultural practices (cropping, fertilizer and pesticide use, irrigation, tillage), and other human managements (dam control, sewage discharge, landuse alteration). It determines water yield and supply, streamflow, surface runoff, groundwater recharge, nutrients (N, P), pathogens, bacteria, and sediments, and also feed the changing hydrology and canopy back to CWRF. To enhance result credibility, PSWAT must be objectively calibrated to derive unknown parameters and then validated against surface observations, including precipitation, snow cover, air temperature, vegetation, crop yield, ozone, nitrogen wet deposition, and instream nitrogen loading.
Progress Summary:
The Predictive Soil and Water Assessment Tool (PSWAT), which was developed on the basis of CWRF/SWAT coupling system, formed a solid foundation for achieving our project ultimate goals. This year, we have focused on PSWAT calibration and validation based on retrospective simulations of the observed climate, hydrology, and water quality. Our major achievements during this reporting period are as follows:
▪ We have further improved the dynamic mapping module in PSWAT, which can now more effectively transfer information between the CWRF grids and the SWAT watershed subbasins.
▪ We have integrated the entire USA reservoir database and comprehensive pollutant sources into the PSWAT coupling system.
▪We conducted a retrospective PSWAT simulation during 1979-2008. PSWAT faithfully reproduces the observed climate, crop production, and water quality. We found that reservoir management has a great effect on the streamflow predictions, especially over the western U.S. mountainous region. The PSWAT can capture the amount and variability of monthly and annual streamflow over most parts of the United States. The model also can predict the corn and soybean yields very well over the upper Mississippi River basin (percent bias is less than 20% for 11 out of four-digit HUCs for both corn and soybean).
▪ We have compared correlation coefficients of the measured streamflow and PSWAT simulated runoff over the entire United States. Correlation coefficients are generously high indicating that PSWAT can be applied to a large watershed such as over the entire United States for the streamflow distribution prediction. The mountainous regions of western United States, however, still need refinements.
▪ We have integrated atmospheric depositions from Community Multiscale Air Quality Modeling system (CMAQ) into the PSWAT to predict EPA nitrogen distribution. Results indicate that land use (agricultural categories) and atmospheric deposition are the main factors affecting the nitrogen geographic distribution over the United States.
▪ We have compared the PSWAT simulations with observations over the conterminous United States and thereby identified key physical processes that need further improvement: (1) snow variations in mountain regions; (2) soil characteristics in semi-arid regions (e.g., western Colorado River basin; (3) terrain aspects in steep mountains; and (4) reservoir and dam managements. These will be the focus of the next year.
Future Activities:
▪ Add extra driving database to predictive SWAT (PSWAT), such as land management, tile drainage, etc.
▪ Diagnose PSWAT output to determine the main factors that affect the stream flow, and then use FFSQP method to optimize the stream flow simulation.
▪ Simulate future projections for 2050 to quantify the individual and combined impacts of global climate and emissions changes on USA water quality using CWRF output scenarios.
▪ On the basis of established PSWAT coupling system, further develop the online version, investigate effects of SWAT feedback information on CWRF, and further improve the prediction capacity and accuracy of climate model by making full use of SWAT detailed hydrological information to refine land surface processes.
▪ Modify relating processes to ameliorate the above-mentioned problems.
▪ Project future water quality change for 2050 and 2010 under the present agricultural practice.
▪ Project future water quality change with potential agricultural adaptation for 2050 and 2010.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 8 publications | 6 publications in selected types | All 6 journal articles |
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Type | Citation | ||
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Srinivasan R, Zhang X, Arnold J. SWAT ungauged:hydrological budget and crop yield predictions in the Upper Mississippi River Basin. Transactions of the ASABE 2010;53(5):1533-1546. |
R834189 (2010) R834189 (2011) R834189 (2012) R834189 (2013) R834189 (Final) |
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Supplemental Keywords:
climate change, hydrological processes, coupled model, nutrient, pathogen, bacteria, sediment, water yield, water supply, streamflow, surface runoff, soil moisture, groundwater recharge, discharge, fertilizer, pesticide, irrigation, drainage, tillage, dam control, urbanization, livestock, GCM, RCM, AQM, WQM, RFA, Air, climate change, Air Pollution Effects, AtmosphereRelevant Websites:
http://www.isws.illinois.edu/atmos/modeling/caqims/compparts.asp?prt=rcm Exit
http://www.wcrp-climate.org/conference2011/abstracts/C43/Liang_C43_TH220A.pdf Exit
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.