Tim Callahan, Associate Professor

Director, M.S. in Environmental Studies Program

Address: RHSC 337
Phone: 843.953.8278
E-mail: callahant@cofc.edu

Education

University of St. Thomas, St. Paul, Minnesota
B.A. Geology, 1991.

New Mexico Institute of Mining and Technology, Socorro
M.S. Geochemistry, 1995. 

New Mexico Institute of Mining and Technology
Ph.D. Earth and Environmental Science (with Dissertation in Hydrology), 2001.

Research Interests

Hydrology and Water Resources

Courses Taught

Hydrology, GEOL 438/EVSS 638
Water Resources, GEOL 238
Wetlands and Watersheds, EVSS 639 (team-taught with Dr. Vijay Vulava)
Dynamic Earth, GEOL 101
Earth History, GEOL 105

Publications

Garrett, C.G., V.M. Vulava, T.J. Callahan, and M.L. Jones. 2012. Groundwater-Surface Water Interactions in a Lowland Watershed: Source Contribution to Stream Flow. Hydrological Processes 26: doi: 10.1002/hyp.8257.

Callahan, T.J., V.M. Vulava, M.P. Passarello, and C.G. Garrett. 2011. Estimating groundwater recharge in lowland watersheds. Hydrological Processes 26 doi: 10.1002/hyp.8356.

La Torre-Torres, I.B., D.M. Amatya, G. Sun, and T.J. Callahan. 2011. Seasonal rainfall–runoff relationships in a lowland forested watershed in the southeastern USA. Hydrological Processes 25: DOI: 10.1002/hyp.7955.

Callahan, T.J., C.G. Garrett, and V.M. Vulava. 2010. The role of groundwater recharge in the water budget of lowland watersheds. Proceedings, 2010 South Carolina Water Resources Conference, October 13-14, 2010, Columbia, SC.

Garrett, C.G., V.M. Vulava, T.J. Callahan, M.L. Jones, and C.L. Ginn. 2010. Using water chemistry data to quatify source contribution to stream flow in a coastal plain watershed. Proceedings, 2010 South Carolina Water Resources Conference, October 13-14, 2010, Columbia, SC.

Amatya, D.M., T.J. Callahan, C.C. Trettin, and A. Radecki-Pawlik. 2009. Hydrologic and water quality monitoring on Turkey Creek watershed, Francis Marion National Forest, SC. Proc., ASABE Int’l Annual Meeting, 21-24 June 2009, Reno, NV. Amer. Soc. Agric. Biol. Engin. Pub. No. 09-5999, St. Joseph, MI.

Beltran, B.J., D.M. Amatya, M. Youssef, M. Jones, T.J. Callahan, R.W. Skaggs, and J.E. Nettles. 2009. Impacts of fertilization on water quality of a drained pine plantation: A worst-case scenario. J. Envir. Qual. 39: 293-303, doi:10.2134/jeq2008.0506.

Amatya, D.M., T.J. Callahan, A. Radecki-Pawlik, P. Drewes, C. Trettin, and W.F. Hansen. 2008. Hydrologic and Water Quality Monitoring on Turkey Creek Watershed, Francis Marion National Forest, SC. In: Proc. 2008 South Carolina Water Resources Conference, October 14-15, 2008, North Charleston, SC. 

Sun, G., J. Boggs, D.M. Amatya, C.C. Trettin, Z. Dai, J.M. Vose, I.B. LaTorre Torres, and T.J. Callahan. 2008. Hydrologic Processes of Forested Headwater Across a Physiographic Gradient in the Southeastern United States. In: Proc. 2008 South Carolina Water Resources Conference, October 14-15, 2008, North Charleston, SC.

Vulava, V.M., C.G. Garrett, C.L. Ginn, and T.J. Callahan. 2008. Application of geochemical end-member mixing analysis to delineate water sources in a lowland watershed. In: Proc. 2008 South Carolina Water Resources Conference, October 14-15, 2008, North Charleston, SC. 

Pyzoha, J.E., T.J. Callahan, G. Sun, and C.C. Trettin. 2008. A conceptual hydrologic model for a forested Carolina bay depressional wetland on the Coastal Plain of South Carolina, USA. Hydrol. Process. 22 (14):2689-2998. doi:10.1002/hyp6866. 

Reimus, P.W. and T.J. Callahan. 2007. Matrix Diffusion Rates in Fractured Volcanic Rock at the Nevada Test Site:  Evidence for a Dominant Influence of Effective Fracture Apertures. Water Resour. Res. 43:W07421. doi:10.1029/2006WR005746.

Reimus, P.W., T.J. Callahan, S.D. Ware, M.J. Haga, and D.A. Counce. 2007. Matrix Diffusion Coefficients in Volcanic Rocks at the Nevada Test Site: Influence of Matrix Porosity, Matrix Permeability, and Fracture Coating Minerals. J. Contam. Hydrol. 93:85-95.

Harder, S.V., D.M. Amatya, T.J. Callahan, C.C. Trettin, and J. Hakkila. 2007. Hydrology and Water Budget for a First Order Forested Coastal Plain Watershed, South Carolina. J. Amer. Water Resour. Assoc. 43(3):563-575. doi: 10.1111/j.1752-1688.2007.00035.x. 

Sun, G., T.J. Callahan, J.E. Pyzoha, and C.C. Trettin. 2006. Modeling the Climatic and Geomorphologic Controls on the Hydrology of a Carolina Bay Wetland, South Carolina, USA. Wetlands 26(2):567-580.

Amatya D.M., C.C. Trettin, R.W. Skaggs, M.K. Burke, T.J. Callahan, G. Sun, J.E. Nettles, J.E. Parsons, and M. Miwa. 2005. Five hydrologic studies conducted by or in cooperation with the Center for Forested Wetlands Research, USDA Forest Service. USDA Forest Service Report, Research Paper SRS-40, Asheville, NC.

Dickerson, D. and T.J. Callahan. 2005. Students' Conceptions of Scale Regarding Groundwater. J. Geosci. Educ. 53(4):374-380.

Sun, G., T.J. Callahan, J.E. Pyzoha, C.C. Trettin, and D.M. Amatya. 2004. Modeling the hydrologic processes of a depressional forested wetland in South Carolina, U.S.A. In: Proc. 6th Int’l. Conf. on Hydrosci. and Engin. (ICHE-2004), 30 May-3 June 2004, Brisbane, Australia.

Callahan, T.J., J.D. Cook, M.C. Coleman, D.M. Amatya, and C.C. Trettin. 2004. Measuring and Modeling Storm Water Runoff and Soil Interflow in a Managed Forest, Upper Coastal Plain of the Southeast US. In: Proc. ASAE/CSAE Annual Int’l. Meeting, 1-4 August 2004, Ottawa, Ontario, Canada.

Reimus, P.W., M.J. Haga, A.I. Adams, T.J. Callahan, H.J. Turin, and D.A. Counce. 2003. Testing and parameterizing a conceptual solute transport model in saturated fractured tuff using sorbing and nonsorbing tracers in cross-hole tracer tests. J. Contam. Hydrol. 62-63:613-626. 

Callahan, T.J., P.W.Reimus, P.C. Lichtner, and R.S. Bowman. 2002. Multicomponent effects on the transport of cations undergoing ion exchange in fractured media. In: Bridging the Gap Between Measurement and Modeling in Heterogeneous Media (A. N. Findikakis, ed.). Proc. Int’l. Groundwater Symposium, Lawrence Berkeley National Laboratory, 25-28 March 2002, Berkeley, California, USA. pp. 523-528.

Callahan, T.J., P.W. Reimus, R.S. Bowman, and M.J Haga. 2000. Using multiple experimental methods to determine fracture/matrix interactions and dispersion of nonreactive solutes in saturated volcanic rock. Water Resour. Res. 36(12):3547-3558.