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Gerard McMahon

Center Director, Southeast Climate Science Center

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Short Biography

Johns Hopkins Univ (9/70-6/74)         Political Economics                 AB (1974)

U Missouri - Columbia (9/74-6/76)     Agricultural Economics          MS (1976)

UNC-Chapel Hill (8/83-6/85)            City/Regional Planning            MCRP (1985)

UNC-Chapel Hill (8/88-6/95)             City/Regional Planning           Ph.D. (1995)

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Coles, J.F., McMahon, Gerard, Bell, A.H., Brown, L.R., Fitzpatrick, F.A., Scudder Eikenberry, B.C., Woodside, M.D., Cuffney, T.F., Bryant, W.L., Cappiella, Karen, Fraley-McNeal, Lisa, and Stack, W.P., 2012, Effects of urban development on stream ecosystems in nine metropolitan study areas across the United States: U.S. Geological Survey Circular 1373, 138 p., available at


Kashuba, Roxolana, McMahon, Gerard, Cuffney, T.F., Qian, Song, Reckhow, Kenneth, Gerritsen, Jeroen, and Davies, Susan, 2012, Linking urbanization to the Biological Condition Gradient (BCG) for stream ecosystems in the Northeastern United States using a Bayesian network approach: U.S. Geological Survey Scientific Investigations Report 2012–5030, 48 p.


Qian, S.S., and T.F. Cuffney, T.F, and McMahon, Gerard, 2012. Multinonmial regression for analyzing macroinvertebrate assemblage composition data. Journal of Freshwater Science v. 31, no. 3, p. 681–694.


Cuffney, T.F., Kashuba, R.O., Qian, S.S., Alameddine, I., Cha, Y.K., Lee, B., Coles, J.F., and McMahon, G., 2011 Multilevel regression models describing regional patterns of invertebrate and algal responses to urbanization across the United States: Journal of the North American Benthological Society. v. 30, no. 3, p 779–786.


Qian, S.S., Cuffney, T.F., Alameddine, Ibrahim, McMahon, Gerard, and Reckhow, K.H.. 2010. On the application of multilevel modeling in environmental and ecological studies. Ecology 91:355–361.


Hoos, A.B. and McMahon, Gerard, 2009, Spatial analysis of instream nitrogen loads and factors controlling nitrogen delivery to streams in the southeastern United States using spatially referenced regression on watershed attributes (SPARROW) and regional classification frameworks: Hydrologic Processes, 23(16):2275-2294


Brown, L.R., Cuffney, T.F., Coles, J.F., Fitzpatrick, Faith, McMahon, Gerard, Steuer, J.J., Bell, A.H., and May, J.T., 2009, Urban streams across the USA: lessons learned from studies in 9 metropolitan areas, J. N. Am. Benthol. Soc., 28(4):1051–1069.


McMahon, G, 2007. Consequences of land-cover misclassification in models of impervious surface. Photogrammetric Engineering and Remote Sensing. 73(12): 1343-1353.


Qian, S.S., K.H. Reckhow, Zhai, J., G. McMahon, Gerard, 2005,   Nonlinear regression modeling of nutrient loads in streams -- a Bayesian approach. Water Resources Research, 41(7):W07012, 2005.


McMahon, Gerard, Benjamin, S.P., Clarke, K., Findley, J.E., Fisher, R.N., Graf, W.L., Gundersen, L.C., Jones. J.W., Loveland, T.R., Roth K.S., Usery, E.L., and Wood, N.J., 2005, Geography for a changing world: A science strategy for the geographic research of the U.S. Geological Survey, 2005-2015: U.S. Geological Survey Circular 1281.


Wolock, D.M., Winter, T.C., and McMahon, Gerard, 2004, Delineation and evaluation of hydrologic-landscape regions in the United States using geographic information system tools and multivariate analysis. Environmental Management, v. 34, suppl. 1, p. S71-78. 


McMahon, Gerard, Wiken, E.B., and Gautier, D.A., 2004, Toward a scientifically rigorous basis for developing mapped ecological regions: Environmental Management, v. 34, suppl. 1, p. S111-S124.


McMahon, Gerard, Bales, J.D., Coles, J.F., Giddings, E.M.P., and Zappia, H. 2003, Use of stage data to characterize hydrologic conditions in an urbanizing environment. Journal of the American Water Resources Association 39(6): 1529-1546.


McMahon, Gerard, Alexander, R.B., and Qian, S. 2003, Support of TMDL programs using spatially referenced regression models. ASCE Journal of Water Resources Planning and Management 129(4): 315-329.


McMahon, Gerard, Gregonis, S., Waltman, S., Omernik, J. Thorson, T., Freeouf, J., Rorick, A., and Keyes, J. 2001. Developing a spatial framework of common ecological regions for the conterminous United States.  Environmental Management, 28(3): 293-316.


McMahon, Gerard and Cuffney, T.F., 2000, Quantifying urban intensity in drainage basins for assessing stream ecological conditions, Journal of the American Water Resources Association, 36(6): 1247-1261.


Godschalk, D.R., McMahon, Gerard, Kaplan, Abram, and Qin, Wei, 1992, Using GIS for computer‑assisted dispute resolution. Photogrammetric Engineering and Remote Sensing. Vol. 58, No. 8. August 1992, pp. 1209‑1212.


Susskind, Lawrence, and McMahon, Gerard, 1985, The theory and practice of negotiated rulemaking. Yale Journal of Regulation, 3:133-165.





My Science Topics

Science Topic
Water Resourceswater quality

My USGS Science Strategy Areas

Understanding Ecosystems & Predicting Ecosystems Change

Climate Variability & Change

Urbanization, nutrient modeling, regional geography

Effects of urbanization. Activities include the design and implementation of multiple National Water-Quality Assessment (NAWQA) projects to study the interrelation of urbanization and physical, chemical, and biological water-quality responses. Responsible for GIS-based characterization of physical and socioeconomic descriptors for study watersheds; development of metrics for hydrologic variability based on continuous stage data; and analysis of the relation between basin characteristics and hydrologic variability.

Nutrient fate and transport modeling. Activities include calibrating a spatially referenced regression model (SPARROW) for three major coastal North Carolina drainage basins to estimate the effects of nutrient sources, landscape characteristics, and in-stream processes on nutrient loading. Responsible for developing spatial and tabular data and for model calibration.

Landscape regionalization. Activities include participating in Federal interagency committee for developing a map of commonly used ecological regions, developing spatial environmental frameworks for local and national NAWQA Program use, and participation in the USGS ecoregionalization science plan development.

Professional memberships

American Water Resources Association

American Geophysical Union

Association of American Geographers

Contact Information

Gerard McMahon
David Clark Labs, NC State Univ
Raleigh, NC 27695-7617
919-515-5327 - Fax
919-604-2572 - Mobile
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