Todd Caldwell

Assistant Research Soil Scientist

Division of Earth and Ecosystem Sciences

Email: Todd.Caldwell@dri.edu

Right: Todd Caldwell standing beside a disc permeameter set-up used to measure hydraulic conductivity of soil surfaces

Education

Professional Interests

Mr. Caldwell is a hydrologist and soil scientist specializing in field investigations and numerical modeling associated with near-surface vadose zone hydrology, landscape restoration, and soil evolution. He is currently enrolled at the University of Nevada, Reno seeking his Ph. D. in the Hydrologic Sciences Program while continuing his professional career at the Desert Research Institute. His current research focuses on the ecohydrology and restoration of arid lands, the characterization and scaling of soils and hydraulic parameters, and soil moisture monitoring and data acquisition. He is also the Soil Characterization Laboratory supervisor and oversees its management.

Research

Areas of Interest and Expertise

• Transport of water, solute and heat through soils
• Soil hydraulic parameter characterization
• Numerical modeling of soil-atmosphere-plant systems
• Soil degradation and arid lands restoration
• Remote site instrumentation and data acquisition

Current Projects

• Catalina Island Automated Climate Network
• Global Military Operating Environments: Linking Natural Environments, International Security, and Military Operations (GMOE)
• Master Environmental Reference Site (MERS): Deformation and recovery of desert pavements, U.S. Army Yuma Proving Ground.
• Measuring Heterogeneities of Soil Hydraulic Properties from Canopy to Interspace

Past Projects

• Integrated Site Design for the Restoration of Military Lands, Ft. Irwin, CA
• Seedbed Microclimate: Modeling and Monitoring Soil Moisture in Support of the Restoration of Military Lands
• Geochemical and Physical Characteristics of Iraqi Dust and Soil Samples
• Remote Sensing for Mapping Near-Surface Playa Moisture
• Geochemical and Physical Characteristics Of Vehicle Endurance and Dust Test Courses at U.S. Army Yuma Proving Ground
• Soil Evaluation in Support of Estimating Carrying Capacity and Landscape Degradation at the NTC – Fort Irwin, California
• Landscape Position and Hillslope Hydrology Associated with the Middle Ranch Hayfield Restoration, Catalina Island, CA
• Uranium Oxide Soil Stabilization Study, Yuma Proving Ground, AZ
• Analysis of Desert Shrubs Along First-order Channels on Desert Piedmonts: Possible Indicators of Ecosystem Health and Historic Variation
• Basic Research Linkages Among the Soil-Hydrologic-Biologic Systems Common to the Desert Piedmonts, U.S. Army Yuma Proving Grounds

Selected Publications

Peer Reviewed Manuscripts

Caldwell, T.G., D.W. Johnson, W.W. Miller, R.G. Qualls, and R.R. Blank. 2009. Prescription fire and anion retention in Tahoe forest soils. Soil Sci. 174:594-600.

Caldwell, T.G., E.V. McDonald, and M.H. Young. 2009. The seedbed microclimate and active revegetation of disturbed lands in the Mojave Desert. J. Arid Environ. 73:563-573.

Caldwell, T.G., M.H. Young, and J. Zhu. 2008. Spatial structure of hydraulic properties from canopy to interspace in the Mojave Desert. Geophys. Res. Lett. 35, L19406, doi:10.1029/2008GL035095.

Caldwell, T.G., E.V. McDonald, S.N. Bacon, and G. Stullenbarger. 2008. The performance and sustainability of vehicle dust courses for desert military testing. J. Terramechanics 45:213-221.

Caldwell, T.G., E.V. McDonald, and M.H. Young. 2006. Soil disturbance and hydrologic response at the National Training Center, Ft. Irwin, California. J. Arid Environ. 67:456-472.

Caldwell, T.G., D.W. Johnson, W.W. Miller, and R.G. Qualls. 2002. Forest floor carbon and nitrogen losses due to prescription fire. Soil Sci. Soc. Amer. J. 66:262-267.

Co-authored Manuscripts

Bacon, S.N., E.V. McDonald, S. Baker, T.G. Caldwell, and G. Stullenbarger. 2008.Desert terrain characterization of landforms and surface cover within vehicle test courses at U.S. Army Yuma Proving Ground, USA. J. Terramechanics 45:167-183.

Bacon, S.N., E.V. McDonald, T.G. Caldwell, and G.K. Dalldorf. In press. Timing and distribution of alluvial fan sedimentation in response to strengthening of the late Holocene ENSO variability in the Sonoran Desert, southwestern Arizona. Quaternary Research.

Berli, M., T.G. Caldwell, E.V. McDonald, and D.A. Gilewitch. In revision. Modeling desert pavement deterioration due to heavy vehicle traffic. J. Terramechanics.

Gee, G.W., A.L. Ward, T.G. Caldwell, and J.C. Ritter. 2002. A vadose zone water fluxmeter with divergence control. Water Resour. Res. 38(8), 10.1029/2001WR000816.

Johnson, D.W., R.B. Susfalk, R.A. Dahlgren, T.G. Caldwell, and W.W. Miller. 2001. Nutrient fluxes in a snow-dominated, semi-arid forest: Spatial and temporal patterns. Biogeochem. 55(3): 219-245.

Johnson, D.W., R.B. Susfalk, T.G. Caldwell, J.D. Murphey, W.W. Miller, and R.F. Walker. 2004. Fire effects on carbon and nitrogen budgets in forests. Water Air Soil Pollut. 4:263-275.

McDonald, E.V., and T.G. Caldwell. 2008. Geochemical characteristics of Iraqi dust and soil samples and related impacts to weapon malfunction, p. 258-265. In C.P. Nathanail, R.J. Abrahart, and R.P. Bradshaw (eds.) Military Geography and Geology: History and technology. Land Quality Press, Nottingham, UK.

Miller, J.M., T.G. Caldwell, M.H. Young, and G.K. Dalldorf. 2008. Verifying curve numbers in arid environments by combining detailed geomorphic mapping and pedotransfer functions. In, Proceedings from the ASCE “the World Environmental and Water Resources Congress 2008, Ahupua'a: Sustainability from the Mountains to the Sea.” CD-ROM, 10 pp.

Shafer, D.S., M.H. Young, S.F. Zitzer, T.G. Caldwell and E.V. McDonald. 2007. Interrelated pedogenic, hydraulic, biotic and abiotic processes during the past 125 000 years of landscape evolution in the northern Mojave Desert, Nevada, USA. 69:633-657.

Sisson, J.B., W.L. Bratton, G.W. Gee, J M. Hubbell, J.C. Ritter, and T.G. Caldwell. 2002. Advances in tensiometry for long-term monitoring of soil water pressures. Vadose Zone J. 1:310-315.

Stevenson, B.A., E.V. McDonald, T.G. Caldwell. 2009. Root patterns for Larrea tridentata in relation to soil morphology in Mojave Desert soils of different ages, p. 312-338. In R.H. Webb, L.F. Fenstermaker, J.S. Heaton, D.L. Hughson, E.V. McDonald, and D.M. Miller (eds.), The Mojave Desert: Ecosystem Processes and Sustainability. University of Nevada Press. Reno, NV.

Young, M.H., T.G. Caldwell, D.G. Meadows, and L.F. Fenstermaker. 2009. Variability of soil physical and hydraulic properties at the Mojave Global Change Facility, Nevada: Implications for water budget and evapotranspiration. J. Arid Environ. 73:733-744.

Young, M.H., E.V. McDonald, T.G. Caldwell, S.G. Benner, and D.G. Meadows. 2004. Hydraulic Properties of a desert soil chronosequence in the Mojave desert, USA. Vadose Zone J. 3: 956-963.