Derek Ryter, Ph.D.


Derek Ryter is a hydrogeologist with interests and experience in several different areas including numerical groundwater-flow modeling, geophysics, process geomorphology, and seismic hazards. He has worked at the USGS since 2008 principally on groundwater resource problems and modeling. He also studies landscape processes (plant consumptive use and recharge) and interactions between surface water and groundwater. He has worked in academia, private industry, and for the Bureau of Reclamation. He has worked in California, Oregon, Colorado, Nebraska, Virginia, and Oklahoma, and projects in the Mediterranean region.


Derek's numerical groundwater-flow modeling experience

  • Derek is lead Hydrogeologist and modeler for a hydrogeologic study of the groundwater resources of the Osage Nation in north-central Oklahoma. This project has collected area-wide helicopter-borne electromagnetic data to characterize salinity of groundwater that will be used in numerical groundwater-flow model of the bedrock and alluvial aquifers.
  • Derek built multi-layer model of the Citizen Pottawatomie Nation jurisdictional area in central Oklahoma. This model will help the tribe deal with water availability and quality issues and locate new wells as water demands increase. It uses the Groundwater Management Process for MODFLOW to maximize water extraction from a surficial aquifer near a river while minimizing streamflow depletion and aquifer drawdown.
  • Derek built a regional-scale transient integrated hydrologic model of the North Canadian River system in western and central Oklahoma. It will be published in 2014. This study includes more than 200 miles of intermittent and perennial stream flowing on a thin alluvial aquifer. The model uses the SFR package, the Lake Package with reservoir releases, a soil-water balance model for transient recharge, transient municipal and irrigation pumping, and multiple water users.
  • Derek supported the Williston Basin regional water availability study model by producing regional-scale potentiometric-surface maps for three hydrogeologic units of the lower Tertiary and upper Cretaceous strata in the basin. The hydrogeological framework was published in 2014.
  • Derek built, calibrated, and used  a transient model of the Central Oklahoma aquifer for groundwater availability. This was a 23-year transient, regional model that used multi-node wells, the SFR package, and used the SWB code to estimate transient recharge. This was published in 2013.
  • Derek constructed and ran a model for the Papio-Missouri River Natural Resources District near Omaha, Nebraska. This model used the SFR and the Farm Process to simulate the groundwater flow with crop-demand driven irrigation pumping. The simulation covered 2000-2010 and included the Platte River and the Lincoln and Omaha municipal well fields.
  • Derek built, calibrated, used a 20-year (1986-2006) transient model for high-capacity well siting in east-central Nebraska. Model included 3 layers, more than 200 irrigation wells, irrigation demands based on crops and precipitation, irrigation return flow, and a high-capacity well pumping 1,100 GPM continuously for a planned ethanol plant. The model was run with the high-cap well running and the total and percentage loss in yield felt by all affected irrigation wells were calculated and mapped. Loss was calculated for the driest year during the model run.
  • Derek built, calibrated, and used a 20-year transient model (1986-2006) to simulate the impact of a proposed flood-control dam on Elm Creek in central Nebraska. Local farmers and residents were worried about groundwater mounding. The model used the Lake Package with MODFLOW, projected runoff and reservoir levels, and irrigation pumping. The model results were presented at public meetings.
  • Derek supported several regional groundwater models in the Nebraska Water Science Center, including the Elkhorn-Loup model. He ran base-flow separation for water budget and flux targets. He also ran numerous soil-water balance models to estimate transient, spatially distributed recharge. 



B.S. Geology: Fort Lewis College, Durango, CO, 1987

M.S. Geological Sciences: Old Dominion University, Norfolk, VA, 1989

Ph.D. Geological Sciences: University of Oregon, Eugene, OR, 2002

USGS Training:

Optimal management of flow in groundwater systems; Paul Barlow, instructor

Parameter Estimation using PEST; Michael Fienen, instructor







Peterson, S.M, Flynn, A.T., Vrabel, Joseph, and Ryter, D.W., 2015, Simulation of groundwater flow and analysis of the effects of water-management options in the North Platte Natural Resources District, Nebraska: U.S. Geological Survey Scientific Investigations Report 2015–5093, 67 p., [Link]

Ryter, D.R., Kunkel, C.D., Peterson, S.M., and Traylor, J.P., 2015, Numerical simulation of groundwater flow, resource optimization, and potential effects of prolonged drought for the Citizen Potawatomi Nation Tribal Jurisdictional Area, central Oklahoma, U.S. Geological Survey Scientific Investigations Report 2014–5167, 27 p., http://dx.doi. org/10.3133/sir20145167. [Link]

Ryter, D.W., and Correll, J.S., 2016, Hydrogeological framework, numerical simulation of groundwater flow, and effects of projected water use and drought for the Beaver-North Canadian River alluvial aquifer, northwestern Oklahoma: U.S. Geological Survey Scientific Investigations Report 2015–5183, 63 p.,

Thamke, J.N., LeCain, G.D., Ryter, D.W., Sando, Roy, and Long, A.J., 2014, Hydrogeologic framework of the uppermost principal aquifer systems in the Williston and Powder River structural basins, United States and Canada: U.S. Geological Survey Scientific Investigations Report 2014–5047, 38 p. [Link]

Mashburn, S.L., Ryter, D.W., Neel, C.R., Smith, S.J., and Magers, J.S., 2013, Hydrogeology and simulation of groundwater flow in the Central Oklahoma (Garber-Wellington) Aquifer, Oklahoma, 1987 to 2009, and simulation of available water in storage, 2010–2059, U.S. Geological Survey Scientific Investigations Report 2013–5219, 92 p.,[Link]

McGuire, V.L., Ryter, D.W., and Flynn, A.S., 2012, Altitude, age, and quality of groundwater, Papio-Missouri River Natural Resources District, eastern Nebraska, 1992 to 2009: U.S. Geological Survey Scientific Investigations Report 2012–5036; 68 p. [Link]

Stanton, J. S., Ryter, D. W. and Peterson, S. M. (2012), Effects of Linking a Soil-Water-Balance Model with a Groundwater-Flow Model. Ground Water. doi: 10.1111/j.1745-6584.2012.01000.x.

Stanton, J.S., Qi, S.L., Ryter, D.W., Falk, S.E., Houston, N.A., Peterson, S.M., Westenbroek, S.M., and Christenson, S.C., 2011, Selected approaches to estimate water-budget components of the High Plains, 1940 through 1949 and 2000 through 2009: U.S. Geological Survey Scientific Investigations Report 2011–5183, 79 p. [Link]

Ryter, D. W., 2009, Estimating transient groundwater recharge using the soil-water balance method for the Elkhorn-Loup model area, north-central Nebraska, Geological Society of America, 2009 annual meeting Abstracts with Programs, Portland, OR, p. 174.

Fall, P.L., Falconer, S.E., Horowitz, M., Hunt, J., Metzger, M.C., and Ryter, D., 2008, Boronze Age settlement and landscape of Politiko-Troullia, 2005-2007, Report of the Department of Antiquities, Cyprus, Lefkosia.

Ryter D. W., 2002, Late Pleistocene kinematics of the central San Jacinto fault zone, Southern California [Ph.D. Dissertation]: University of Oregon, Eugene, OR, 137 p.

Miller, M. G., Ryter, D. W., and Soule, S. A., 2000, Drawing contours on clay models--a hands-on introduction to topographic maps: Journal of Geoscience Education, v. 48, p. 596.

Dorsey, R. J., and Ryter, D. W., 2000, Stratigraphic and Geomorphic Evidence for Pleistocene Initiation of the San Jacinto Fault Zone, in American Geophysical Union Fall Meeting, Supplement to EOS, Transactions, San Francisco, CA, p. F1141.

Ryter, D. W., and Dorsey, R. J., 1999, Structural, geomorphic, and geophysical evidence for kinematics of late Pleistocene to Holocene slip on the Clark fault, SE California, in American Geophysical Union Fall Meeting, Supplement to EOS, Transactions, San Francisco, CA, p. F1003.

Beason, S. C., Turlington, G. A., Lung, R. C., Eatman, L. W., Ryter, D., Barr, 1996, Geology of the North Ramp - Station 0+60 to 4+00, Exploratory Studies Facility, Yucca Mountain Project, Yucca Mountain, Nevada, Denver, Colorado: U.S. Geological Survey. ACC: MOL.19970106.0449, 175 p.

Ryter, D.R., and Vetter, U.R., 1994, Seimotectonic Study for Gerber Dam, Deschutes Project, Oregon, Seismotectonic Report 94-1, Seismotectonics and Geophysics Section, Geology Branch, Bureau of Reclamation, Denver, CO, 29 p., Appendix.

Ryter, D.R., and Vetter, U.R., 1993, Seimotectonic Study for Haystack Dam, Deschutes Project, Oregon: Seismotectonic Report 93-1, Seismotectonics and Geophysics Section, Geology Branch, Bureau of Reclamation, Denver, CO, 35 p., Appendix.

Ryter, D.W., 1993, Crosshole shear wave velocity measurements for MDA analysis: Haystack Dam, Oregon: Bureau of Reclamation, Geotechnical Engineering and Geology Branch, Technical Memorandum 3610-93-05, 3 p., 8 figs.

Whittecar, G. R., and Ryter, D. W., 1992, Boulder streams, debris fans, and Pleistocene climate change in the Blue Ridge Mountains of central Virginia: Journal of Geology, v. 100, no. 4, pp. 487-494.

Giardino, J. R. Waters, M., Ryter, D., 1992, Using geomorphology to reconstruct former historic shorelines in St. Ann's Bay, Jamaica; the search for Columbus' Caravels, in The Association of American Geographers 88th annual meeting.