Page Banner

United States Department of Agriculture

Agricultural Research Service

Timothy O Keefer (Tim)
Southwest Watershed Research
Hydrologist

Phone: (520) 647-9173
Fax: (520) 670-5550
Room 413
2000 E ALLEN RD
TUCSON, AZ, 85719-1596


Publications (Clicking on the reprint icon Reprint Icon will take you to the publication reprint.)
Uncertainity in measuring runoff from small watersheds using instrumented outlet-pond - (Peer Reviewed Journal)
Nichols, M.H., Anson, E.L., Keefer, T.O. 2014. Uncertainity in measuring runoff from small watersheds using instrumented outlet-pond. Transactions of the ASABE. 57(3):851-859. DOI:10.13031/trans.57.10504.
Report on the projected future climate of the Walnut Gulch Watershed, AZ - (Research Notes)
Garbrecht, J.D., Keefer, T.O., Goodrich, D.C., Busteed, P.R. 2013. Report on the projected future climate of the Walnut Gulch Watershed, AZ. Grazinglands Research Laboratory Miscellaneous Publication. Available: http://iapreview.ars.usda.gov/main/site_main.htm?modecode=62-18-05-20.
Utilizing long-term ARS data to compare and contrast hydroclimatic trends from snow and rainfall dominated watersheds 2142 - (Proceedings) - (06-Sep-11)
Growing season ecosystem and leaf-level gas exchange of an exotic and native semiarid bunchgrass - (Peer Reviewed Journal)
Hamerlynck, E.P., Scott, R.L., Moran, M.S., Keefer, T.O., Huxman, T.E. 2010. Growing season ecosystem and leaf-level gas exchange of an exotic and native semiarid bunchgrass. Oecologia. 163:561–570.
Partitioning evapotranspiration in semiarid grassland and shrubland ecosystems using time series of soil surface temperature 1932 - (Peer Reviewed Journal)
Moran, M.S., Scott, R.L., Keefer, T.O., Emmerich, W.E., Hernandez, M., Nearing, G.S., Paige, G.B., Cosh, M.H., O'Neill, P.E. 2009. Partitioning evapotranspiration in semiarid grassland and shrubland ecosystems using time series of soil surface temperature. Agricultural and Forest Meteorology. 149:59-72.
Event to multidecadal persistence in rainfall and runoff in southeast Arizona 1908 - (Peer Reviewed Journal)
Goodrich, D.C., Unkrich, C.L., Keefer, T.O., Nichols, M.H., Stone, J.J., Levick, L., Scott, R.L. 2008. Event to multidecadal persistence in rainfall and runoff in southeast Arizona. Water Resour. Res., 44, W05S14, doi:10.1029/2007WR006222.
Partitioning evapotranspiration using diurnal surface temperature variation 1861 - (Proceedings)
Moran, M.S., Keefer, T.O., Paige, G.B., Scott, R.L., Emmerich, W.E., Cosh, M.H., O'Neill, P.E. 2008. Partitioning evapotranspiration using diurnal surface temperature variation. 6th Conference on Research and Resources Mgmt. in the Southwestern Desert - Borders, Boundaries and Time Scales, 2-5 May 2006, Tucson, Az., Proc. Published by USGS Sonoran Desert Research Station. 3 p.
Long-term precipitation database, Walnut Gulch Experimental Watershed, Arizona, United States 1864 - (Peer Reviewed Journal)
Goodrich, D.C., Keefer, T.O., Unkrich, C.L., Nichols, M.H., Osborn, H.B., Stone, J.J., Smith, J.R. 2008. Long-term precipitation database, Walnut Gulch Experimental Watershed, Arizona, United States. Water Resources Research, Vol. 44, W05S04, doi:10.1029/2006WR005782.
Long-term meteorological and soil hydrology database, Walnut Gulch Experimental Watershed, Arizona, United States 1844 - (Peer Reviewed Journal)
Keefer, T.O., Moran, M.S., Paige, G.B. 2008. Long-term meteorological and soil hydrology database, Walnut Gulch Experimental Watershed, Arizona, United States. Water Resources Research, Vol. 44, W05S07, doi:10.1029/2006WR005702.
An event-based comparison of two types of automated-recording, weighing bucket rain gauges 1890 - (Peer Reviewed Journal)
Keefer, T.O., Unkrich, C.L., Smith, J.R., Goodrich, D.C., Moran, M.S., Simanton, J.R. 2008. An event-based comparison of two types of automated-recording, weighing bucket rain gauges. Water Resources Research, Vol. 44, W05S12, doi:10.1029/2006WR005841.
Evaporation and transpiration in semiarid grass- and shrub-dominated ecosystems during the North American monsoon in southeast Arizona 1931 - (Proceedings)
Moran, M.S., Scott, R.L., Keefer, T.O., Emmerich, W.E., Hernandez, M., Paige, G.B., Cosh, M.H., O'Neill, P.E. 2007. Evaporation and transpiration in semiarid grass- and shrub-dominated ecosystems during the North American monsoon in southeast Arizona. American Geophysical Union Meeting, Dec. 10-14, San Francisco, CA. {abstract}.
Appropriate scale of soil moisture retrieval from high-resolution radar imagery for bare and minimally vegetated soils 1859 - (Peer Reviewed Journal)
Thoma, D., Moran, M.S., Bryant, R., Rahman, M., Holifield Collins, C.D., Keefer, T.O., Noriega, R., Osman, I., Skirvin, S., Tischler, M., Bosch, D.D., Starks, P.J., Peters-Lidard, C. 2008. Appropriate scale of soil moisture retrieval from high-resolution radar imagery for bare and minimally vegetated soils. Remote Sensing of Environment. 112:403-414.
Preface to special section on Fifty Years of Research and Data Collection: U.S. Department of Agriculture Walnut Gulch Experimental Watershed 1930 - (Peer Reviewed Journal)
Moran, M.S., Emmerich, W.E., Goodrich, D.C., Heilman, P., Holifield Collins, C.D., Keefer, T.O., Nearing, M.A., Nichols, M.H., Renard, K.G., Scott, R.L., Smith, J.R., Stone, J.J., Unkrich, C.L., Wong, J.K. 2008. Preface to special section on Fifty Years of Research and Data Collection: U.S. Department of Agriculture Walnut Gulch Experimental Watershed. Water Resources Research, Vol. 44, W05S01, doi:10.1029/2007WR006083.
Comparison of field performance of multiple soil moisture sensors in a semi-arid rangeland 1757 - (Peer Reviewed Journal)
Paige, G.P., Keefer, T.O. 2008. Comparison of field performance of multiple soil moisture sensors in a semi-arid rangeland. Journal of the American Water Resources Association (JAWRA) 44(1):121-135. DOI: 10.1111/j.1752-1688.2007.00142.x
Aircraft based soil moisture retrievals under mixed vegetation and topographic conditions - (Peer Reviewed Journal)
Bindlish, R., Jackson, T.J., Gasiewski, A., Stankov, B., Klein, M., Cosh, M.H., Mladenova, I., Watts, c., Vivoni, e., Lakshmi, v., Bolten, J., Keefer, T. 2008. Aircraft based soil moisture retrievals under mixed vegetation and topographic conditions. Remote Sensing of Environment. 112:375-390.
Partitioning Evapotranspiration Using Diurnal Surface Temperature Variation 1830 - (Proceedings) - (15-May-06)
Validation of Amsr-E Soil Moisture Products Using Watershed Networks - (Proceedings)
Jackson, T.J., Cosh, M.H., Zhan, X., Bosch, D.D., Seyfried, M.S., Starks, P.J., Keefer, T.O., Lakshmi, V. 2006. Validation of AMSR-E soil moisture products using watershed networks. In: Proceedings of the International Geoscience and Remote Sensing Symposium, July 31-August 4, 2006, Denver, Colorado. p. 432-435.
Watershed Scale Surface Soil Moisture Variability in the Walnut Gulch Experimental Watershed During the 2004 North American Monsoon - (Abstract Only)
Cosh, M.H., Jackson, T.J., Keefer, T.O. 2004. Watershed scale surface soil moisture variability in the Walnut Gulch Experimental Watershed during 2004 North American Monsoon [abstract]. EOS Transactions, American Geophysical Union, 85(47), Fall Meeting Supplements, Abstract H34D-04.
Instrumentation and Research at the USDA-ARS Walnut Gulch Experimental Watershed 1611 - (Proceedings)
Nichols, M.H., Stone, J.J., Keefer, T.O., Smith, J.R., Moran, M.S., Renard, K.G. 2004. Instrumentation and research at the usda-ars walnut gulch experimental watershed. Proceedings Internat'l. Instrumented Watershed Sym., June 22-25, 2004, Edmonton, Canada, 14 p.
Aerosol Radiative Properties in the Semi-Arid Western United States 1493 - (Peer Reviewed Journal)
Pinker, R., Pandiethurai, G., Holden, B., Keefer, T.O., Goodrich, D.C. 2004. Aerosol radiative properties in the semi-arid Western United States.Atmospheric Research 71:243-252.
Cd-Southwest Watershed Research Center Online Data Access 1606 - (Other)
Nichols, M.H., Anson, E., Stone, J.J., Unkrich, C.L., Keefer, T.O., Wong, J.K. 2004. Southwest Watershed Research Center online data access. Southwest Watershed Research Center Web Site. Available: http://www.tucson.ars.ag.gov
Evaluation of Hyperspectral, Infrared Temperature and Radar Measurements for Monitoring Surface Soil Moisture 1517 - (Proceedings)
Bryant, R., Thoma, D., Moran, M.S., Holifield, C.D., Goodrich, D.C., Keefer, T.O., Paige, G., Williamd, D., Skirvin, S.M. 2003. Evaluation of hyperspectral, infrared temperature and radar measurements for monitoring surface soil moisture. Proceedings First Interagency Conference on Research in the Watersheds. Oct. 27-30, 2003, Benson, AZ., pp. 528-533.
Evaluation of Hyperspectral, Infrared Temperature and Radar Measurements for Monitoring Surface Soil Moisture 1517 - (Proceedings)
Proc. 1st Interagency Conf. on Research in the Watersheds, Oct. 27-30, 2003, Benson,AZ., pp. 528-523.
Precipitation Simulation Models 1425 - (Review Article)
Keefer, T.O. 2003. Precipitation simulation models. In: Stewart, B.A., Howell, T.A. Encyclopedia of Water Science. New York: Marcell Dekker, Inc. pp. 729-733.
Evaluation of Dielectric Constant-Based Soil Moisture Sensors in a Semiarid Rangeland 1515 - (Proceedings)
Kennedy, J.R., Keefer, T.O., Paige, G.B., Barnes, E. 2003. Evaluation of dielectric constant-based soil moisture sensors in a semiarid rangeland. Proceedings First Interagency Conference on Research in the Watersheds. Oct. 27-30, 2003. Benson, AZ., pp.503-508.
Weather Generator Research and Development - (Abstract Only) - (26-Nov-01)
Analysis of Seasonal, Climate, and Elevation Effects on Times Between Storms - (Proceedings) - (16-Jan-01)
Modeling Multiyear Observations of Soil Moisture Recharge in the Semiarid Southwest 1267 - (Peer Reviewed Journal) - (18-Apr-00)
An Overview of the 1997 Activities of the Semi-Arid Land-Surface-Atmosphere(salsa) Program 1195 - (Proceedings) - (21-Jan-99)
Evaluation of Multiple Flux Measurement Techniques Using Water Balance Information at a Semi-Arid Site 1198 - (Proceedings) - (13-Jan-98)
Monitoring Temporal Soil Moisture Variability with Depth Using Calibrated in-Situ Sensors - (Proceedings) - (01-Nov-97)
Estimating Water Use by Semiarid Rangeland Vegetation During the Summer in Southern Arizona - (Proceedings) - (05-Feb-97)
Infiltration - Scale Interactions - (Proceedings) - (22-Jul-96)
Evaluating Southern Oscillation Seasonal Effects on Parameters of a Daily Precipitation Model - (Proceedings) - (07-Nov-95)
Last Modified: 7/31/2014
Footer Content Back to Top of Page