Paper No. JAWRA-08-0050-P of the Journal of the American Water Resources Association (JAWRA). Discussions are open until six months from print publication.
The Watershed Deposition Tool: A Tool for Incorporating Atmospheric Deposition in Water-Quality Analyses1
Article first published online: 1 JUN 2009
© 2009 American Water Resources Association. No claim to original U.S. government works
JAWRA Journal of the American Water Resources Association
Volume 45, Issue 4, pages 973–985, August 2009
How to Cite
Schwede, D. B., Dennis, R. L. and Bitz, M. A. (2009), The Watershed Deposition Tool: A Tool for Incorporating Atmospheric Deposition in Water-Quality Analyses. JAWRA Journal of the American Water Resources Association, 45: 973–985. doi: 10.1111/j.1752-1688.2009.00340.x
- Issue published online: 29 JUL 2009
- Article first published online: 1 JUN 2009
- Received March 21, 2008; accepted March 3, 2009.
- atmospheric deposition;
- nitrogen loading;
- management tool;
- Total Maximum Daily Load;
- watershed analysis
Abstract: A tool for providing the linkage between air and water-quality modeling needed for determining the Total Maximum Daily Load (TMDL) and for analyzing related nonpoint-source impacts on watersheds has been developed. Using gridded output of atmospheric deposition from the Community Multiscale Air Quality (CMAQ) model, the Watershed Deposition Tool (WDT) calculates average per unit area and total deposition to selected watersheds and subwatersheds. CMAQ estimates the wet and dry deposition for all of its gaseous and particulate chemical species, including ozone, sulfur species, nitrogen species, secondary organic aerosols, and hazardous air pollutants at grid scale sizes ranging from 4 to 36 km. An overview of the CMAQ model is provided. The somewhat specialized format of the CMAQ files is not easily imported into standard spatial analysis tools. The WDT provides a graphical user interface that allows users to visualize CMAQ gridded data and perform further analyses on selected watersheds or simply convert CMAQ gridded data to a shapefile for use in other programs. Shapefiles for the 8-digit (cataloging unit) hydrologic unit code polygons for the United States are provided with the WDT; however, other user-supplied closed polygons may be used. An example application of the WDT for assessing the contributions of different source categories to deposition estimates, the contributions of wet and dry deposition to total deposition, and the potential reductions in total nitrogen deposition to the Albemarle-Pamlico basin stemming from future air emissions reductions is used to illustrate the WDT capabilities.