Dr. Peter Allen

• Urban Environmental Geology

• Engineering Geology

• Hydrology

• Impact of urbanization on stream channels; erosion degradation and aggradation of streams.

• Stream-groundwater interactions and water budget models.

• Recharge mechanisms and bypass flow in clay shale terrain.

• Field techniques for assessment of geological processes as sedimentation and erosion.

For information on the Surface Processes Group, click here.

Before joining the Geology Department, Dr. Allen worked for the City of Dallas as an engineering geologist. While there, he aided in development of geotechnical guidelines for slope ordinances, setbacks from streams for erosion control protection, gravel mining and reclamation, stream corridor assessment for open space planning, flood plain ordinances and erosion control procedures. Currently, he teaches classes in environmental geology, hydrology, engineering geology, and field procedures for environmental site assessment.

Dr. Allen is also currently working with several outside agencies and consulting firms in hydrology and engineering geology. His work also includes partnerships with the Agricultural Research Service of the U.S. Department of Agriculture for work on the SWAT model (Soil Water Assessment Tool), part of the E.P.A. Basins modeling package. This model simulates weather, hydrology, erosion, sediment yield, nitrogen and phosphorus cycling, pesticide fate, and crop growth and management as well as pond and reservoir storage and groundwater flow.

Current work with the ARS is being done in the area of evaluating the effect of cracks in clay soils, (due to dessication), on recharge and runoff in clay shale terrains. Monitoring on the ARS Research watershed in Reisel, Texas over the past two years has indicated cracks can have a profound effect on recharge, lateral flow, and surface runoff characteristics and may effect the effectiveness and toxicity of pesticides and fertilizers in the hydrologic system. Dr. Allen is working with Dr. Dunbar on evaluation of the spatial nature of this phenomena using GPS and towed EM-38 arrays. Models of the shrink-swell system developed in this research are being assessed for use in dealing with expansive soil problems, a 11-17 billion dollar a year problem in the U.S.

Recent work in applied hydrology has dealt with evaluation of the time rates of erosion and channel changes in urbanizing watersheds. This work is done in liason with major civil engineering firms to aid in prioritizing the expenditures for erosion control in the watersheds. Field techniques have been developed using a submerged jet testing device to predict erodibility rates of channel materials. These rates can be used with simple hydrograph techniques or can be input into more sophisticated simulation models such as SWAT-DEG which can simulate erosion in the channel over time from 1-100's of years. In addition, Dr. Allen is working with Dr. Dunbar on assessing sedimentation rates in reservoirs and floodwater retarding structures using sub-bottom accoustical profiling and GPS techniques.

Recent research in stream water interactions is focused on dealing with the water budgets along riparian corridors in association with flood water retarding structures. Dr. Allen is working with a team of scientists (biologist, geophysicist, engineer) on monitoring the water budget through the use of TDR soil moisture probes, sap velocity meters, water and well dataloggers, rain gages, EM-38/34 among other instrumentation.

Arnold, J.G., P.M. Allen, K.N. Potter, and K.W. King, 2002. Estimation of Soil Cracking and the Effect on Surface Runoff in A Texas Blackland Prairie Watershed. Submitted to Hydrological Processes. (Accepted)

Duke, J.R., White, J.D., Allen, P.M., Muttiah, R.S., 2002. Impacts of Flood Impoundments on Water Balances of Downstream Riparian Corridors. (In) Proceedings JAWRA Groundwater/Surface Water Interactions, Keystone, Coloado, July 1-3, pp.1-610.

Bennett, S.J., Cooper, C.M., Ritchie, J.C., Dunbar, J.A., Allen, P.M., Caldwell, L.W., McGee, T.M., 2002. Assessing Sedimentation Issues Within Aging Flood Control Reservoirs in Oklahoma. Journal of the American Water Resources Association, Volume 38, No. 5, pp 1307-1322.

Allen, P.M., Arnold, J.G., Skipwith, W., 2002. Erodibility of Urban Bedrock and Alluvial Channel, North Texas. journal of American Water Reources Association, Vol. 38, No. 5, pp 147-149.

Arnold, J.G., Potter, K.N., Allen, P.M. and King, K.W., 2001, Prediction of Soil Cracking and the Effect on Surface Runoff in a Texas Blackland Prairie Watershed. Proceedings American Society Agricultural Engineers Mtg., Honolulu Hawaii.

Arnold, J.G., Allen, P.M., and Morgan, D., 2001. Hydrologic Model for Design of Constructed Wetlands. Wetlands Journal, Vol. 21, No. 2, pp. 167-178

Arnold, J.G., Muttiah, R.S., Srinivasan, R., Allen. P.M., 2000. Regional Estimation of Base Flow and Groundwater Recharge in the Upper Mississippi River Basin. Journal of Hydrology, 227:21-40.

Dunbar, J.A., Allen, P.M., and P.D. Higley, 2000. Color encoded Multifrequency acoustic profiling for near bottom studies. Geophysics, v. 65, pp. 994-1002.