Grantee Research Project Results
2010 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 , University of Illinois Urbana-Champaign
Current 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, 2009 through July 31,2010
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 ISWS/UIUC 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 3 intergovernmental panel on climate change (IPCC) special report on emissions scenarios (SRES) (low, medium, high) accounting for dynamic landuse 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 U.S. 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 in-stream nitrogen loading.Progress Summary:
The fundament tasks on model development part of the project have been completed for the CWRF-SWAT coupling system. These form a solid basis for achieving our project ultimate goals that will apply the coupled modeling system to reproduce the observed climate and water quality variations and project their future changes. Following are the major achievements during the reporting period:
- We have completed the recoding of the Soil & Water Assessment Tool (SWAT) input data processing component, which is the necessary step for the coupled CWRF-SWAT system. The SWAT is soil and water assessment model, and requires diversity information with several thousands of data files. The CWRF is an extension of WRF; this extension incorporates inclusively all WRF functionalities for Numerical Weather Prediction (NWP) while enhancing the capability for climate applications. The performance of the CWRF-SWAT coupled system is hindered by high frequency input-output operations. It is vital to combine thousands of input files for a large watershed into one file to improve the computational performance of the coupled system, especially when run on supercomputing and parallel facilities. We have accomplished this through intensive and careful re-engineering works. We first classified all input and output variables according to their function and the order of their usage in the program, and then wrote all categories in the sequential order into one binary file. There are three categories: variables that will be initialized by reading operation, variables that are not used in the I/O operation, and variables that are output. As such, only a reading interface is needed between input data processing and model predicting component.
- We have prepared a comprehensive set of input data for SWAT application over the entire Conterminous United States. These include: 1) the primary data derived from Digital Elevation Model (DEM) for the channel length (both the main routing and tributary channel), subbasin channel slope and Hydrologic Response Unit (HRU) overland slope; 2) the Land Use/Land Cover (LULC) and land management as the essential parameters for accurate estimation of various components of the simulating of hydrologic cycle and crop yields; 3) the national State Soil Geographic (STATSGO) soil layer at 1:250,000 scale and distributed with ArcSWAT software installation package for the HRU soil characteristics; 4) the climate data of all variables, including daily precipitation and maximum/minimum temperature, derived from the North American Regional Reanalysis (NARR), which is the best available proxy of observations, for the period of 1979-2008. Note that each HRU is a unique combination of land use, soils, and slope overlay within a subbasin. They are the basic building blocks of SWAT at which all the landscape processes are computed. The slope classes used for this process are 0-1%, 1-3%, 3-5%, 5-8%, and 8% and above, while a land use/soil/slope threshold is 1,000-ha each. As a result, the SWAT predicts hydrologic processes and water quantity and quality variations in 145,581 HRUs over the Conterminous United States.
- We have developed a dynamic mapping module to effectively transfer information between the CWRF grids and the SWAT watershed subbasins in the coupled system. The CWRF has its built-in data structure on regular geographic grids, currently at 30-km resolution, while the SWAT divides the U.S. watersheds into 2,105 eight-digit subbasins, each depicted by a unique Hydrologic Unit Code (HUC). Most SWAT HUCs contain multiple CWRF grids (up to 50 in a few cases), while some HUCs include only one or no grid. A mass-conserving procedure is required to transfer CWRF predictions into SWAT calculations and return as they couple online. This dynamic mapping module has been developed on the basis of the ArcGIS aggregation procedure, and implemented as a memory tracking and allocation with a rule table. This method has been rigorously tested and demonstrated being efficient and flexible.
- We have completed a continuous simulation during 1979-2008 over the entire Conterminous United States using the re-engineered SWAT as driven by the NARR climate data. This is a necessary step to evaluate the performance of the SWAT itself for reproducing the historical observations of the terrestrial hydrologic processes, especially as compared against the USGS streamflow data. The result, while very promising, indicates that global optimization of the SWAT through intelligent system-wide calibrations is needed before full coupling with the CWRF. Our model infrastructure developed facilitates such global optimization, which will be one focus in the new project year.
- We have compared the SWAT outputs with USGS gauge-measured streamflows and demonstrated the feasibility for its coupling with the CWRF. We have also investigated the impact of different watershed areas on streamflow modeling and showed that model errors increase as watershed areas decrease. This sensitivity suggests that the SWAT should be first calibrated separately in watersheds of appropriate area sizes and then refined over the whole United States through a system optimization approach. We are making important progress toward this end.
Future Activities:
Add extra input data to the SWAT-CWRF coupled system, such as land management, point sources, tile drainage, etc.
- Diagnose swat 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 SWAT-CWRF coupled system, further develop the on-line version, investigate effects of SWAT feedback information on CWRF, further improve the prediction capacity and accuracy of climate model by making full use of SWAT detailed hydrological information to refine land surface processes.
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) |
Exit Exit |
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=rcmProgress 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.