Climate Science Program

Contact us

Got a question or comment? Contact us at (515) 294-9871or e-mail

Bill Simpkins




Office: 55 Science I

Phone: 515-294-7814


(Sigma Xi - "Year of H2O")


Department: Geological and Atmospheric Sciences, Environmental Science

Research Interests: physical/chemical hydrogeology, groundwater quality in agricultural watersheds, groundwater/surface water interaction, effects of climate change and biofuels development on groundwater sustainability

Brief description of current research:

Dr. Simpkins' current research is focused in five major areas:
1) the hydrogeology and geochemistry of till and related glacial sediments;
2) the groundwater quality of restored, multi-species riparian buffers in agricultural watersheds;
3) processes controlling nutrient transport via groundwater to lakes and streams in Iowa;
4) application of groundwater modeling to predict the hydrologic effects of conservation practices in agricultural watersheds;
5) assessing the sustainability of alluvial aquifers in central Iowa under changing climate and biofuels development.


Recent publications:

Helmers, M.J., T.M. Isenhart, C.L. Kling, T.M. Moorman, W.W. Simpkins, and Mark Tomer. 2007.  Water quality in Agriculture 101: Heterogeneity of pollutants, practices, and programs. Choices.

Schilling, K.E., M. Tomer, P.E. Gassman, C.L. Kling, T.M. Isenhart, T.B. Moorman, W.W. Simpkins, C.F. Wolter. 2007. A tale of three watersheds: non-point source pollution and conservation practices across Iowa. Choices.

Simpkins, W.W. 2006. A multi-scale investigation of ground water flow at Clear Lake, Iowa. Ground Water 44 (1):35-46.

Helmke, M.F., W.W. Simpkins, and R. Horton. 2005. Simulating conservative tracers in fractured till
under realistic timescales. Ground Water 43 (6):877-889.

Helmke, M.F., W.W. Simpkins, and R. Horton. 2005. Fracture-controlled transport of nitrate and
atrazine in four Iowa till units. J. Environ. Qual. 34:227-236.

Helmke, M.F., W.W. Simpkins, and R. Horton. 2004. Experimental determination of effective diffusion parameters in fractured till. Vadose Zone Journal 3:1050-1056.

Burkart, M.R., W.W. Simpkins, A.J. Morrow, and J.M. Gannon. 2004. Occurrence of total dissolved phosphorus in surficial aquifers and aquitards in Iowa. J. Amer. Water Resources Assoc. 40(3):827-834.

Schultz, R.C., T.M. Isenhart, W.W. Simpkins, and J.P. Colletti. 2004. Riparian forest buffers in agroecosystems – lessons learned from the Bear Creek Watershed, central Iowa, USA. Agroforestry Systems 61:35-50.