TDE Soil Water Data:

TDR Measurements of Soil Water Content and Calculated Soil Water Potentials


1.0 DOCUMENT INFORMATION
1.1 Document Title: TDE Soil Water Data By TDR
1.2 Revision Date:  August 23, 2005
1.3 Document Summary:   Periodic measurements of soil water content by TDR 1993-2005.
1.4 Sponsor: Office of Biological and Environmental Research, U. S. DOE

 2.0 INVESTIGATOR
2.1 Investigator and data set contact:

P.J. Hanson (hansonpj@ornl.gov)
Environmental Sciences Division
Oak Ridge National Laboratory
Building 1059, P.O. Box 2008
Oak Ridge, TN 37831-6422
2.2 Title Of Investigation:
Walker Branch Throughfall Displacement Experiment (TDE)

 3.0 DATA SUMMARY
Mean daily soil water content data for the TDE treatment plots including data for the 0-35 cm depth, 0-70 cm depth and derived data for the 35-70 cm depth.  Estimates of soil water potential for the 0-35 and 35-70 depth increments are also provided.

 4.0 PROCEDURES
Soil water content (%, v/v) was measured with a time domain reflectometer (TDR; Soil Moisture Equipment Corp., Santa Barbara, California) following the procedure of Topp and Davis (1985) as documented for soils with high coarse fraction content (Drungil et al. 1987).  Three hundred ten sampling locations were installed at an 8 x 8 meter spacing across the site giving more than 100 soil water monitoring locations per plot.  At each location two pairs of TDR waveguides were installed in a vertical orientation (0-0.35 and 0-0.7 m).  The surface (0-0.35 m) TDR measurements coincide with the zone of maxium root density in these soils.  TDR measurements were obtained biweekly during the growing season and approximately monthly during the dormant season.  The TDR soil water content measurements were adjusted for the coarse fraction of these soils (mean coarse fraction of 14%) and converted to soil water potentials using laboratory derived soil moisture retention curves for the A, A/E and E/B horizons (Hanson et al. 1998).

Starting in 2002 the spatial detail of the soil water content observations was scaled back, and the measurements were only collected for a single upper, middle and lower transect across the TDE site.

 5.0 OBSERVATION NOTES
None

 6.0 DATA ORGANIZATION

Data are provided in comma delimeted text files where the first line includes the variable names and subsequent lines include the following data by month.

6.1 Variable, Definition, and Units

6.2 Number of Records: 177 dates
6.3 Missing data: Missing data are present and represented by blanks between commas.
6.4 Related Data Sets: Hourly data sets for soil water content (% v/v) and soil water potential are available for 1998, 1999, and 2000.  Complete files of all individual TDR data collected from 1992 through 2005 are also available.

7.0 KNOWN ERRORS AND QUALITY ASSESSMENT
These daily data and the original hourly data from which they were derived have been checked for errors and missing data. If bad or missing data were found approximate replacement data were obtained from other weather data sources in the area.

8.0 NOTES
8.1 Limitations of the data:     None.
8.2 Known Problems With The Data:     None.
8.3 Usage Guidance:     None.

 9.0 REFERENCES:

Hanson, P.J., D.E. Todd, N.T. Edwards, and M.A. Huston.  1995.  Field performance of the Walker Branch Throughfall Displacement Experiment,   In:  A. Jenkins, R.C. Ferrier, and C. Kirby, eds., Ecosystem Manipulation Experiments: scientific approaches, experimental design and relevant results, Ecosystem Research Report #20, Commission of the European Communities, pp. 307-313

Hanson, P.J., D.E. Todd, M.A. Huston, J.D. Joslin, Jennifer Croker, and R. M. Augé. 1998.  Description and field performance of the Walker Branch Throughfall Displacement Experiment: 1993-1996, ORNL/TM-13586, Oak Ridge National Laboratory, Oak Ridge, Tennessee

Hanson P.J. 2000.  Large-scale Water Manipulations -- chapter 23 In: O.E. Sala, R.B. Jackson, H.A. Mooney, and R.W. Howarth, eds.  Methods in Ecosystem Science, Springer-Verlag, New York.  pp. 341-352

Hanson, P.J. , D.E.Todd and J.S. Amthor.   2001.  A six year study of sapling and large-tree growth and mortality responses to natural and induced variability in precipitation and throughfall.   Tree Physiology 21:345-358

Hanson PJ, Todd DE, Huston MA (2003) Walker Branch Throughfall Displacement Experiment (TDE) In: Hanson PJ, Wullschleger SD, Eds, North American Temperate Deciduous Forest Responses to Changing Precipitation Regimes. Springer, New York, pp. 8-31.

 10.0 DATA LISTING

Click on the following to view data for the listed year.
Once open the files can exported as text files with the 'Save As' command.

TDR soil water content data 1993 through August 22, 2005
 


Revision Date:  23 August 2005