PURPOSE
To study hydrology of streams draining tallgrass prairie catchments, to estimate surface losses of nitrogen (see data set NWC01), and to compare runoff and nutrient loss characteristics among four different burn frequencies (1-, 2-, and 4-year intervals, and unburned).
LOCATION OF SAMPLING STATIONS
Flumes are located at the base of each catchment (ASD02): N02B, N20B, N04D, and N01B. ( See Fig. 7).
FREQUENCY OF SAMPLING AND VARIABLES MEASURED
Stream gage height is recorded every five minutes on the CR-21X datalogger (Campbell Scientific Co.). Each record also includes Julian day and time. Temperature is recorded hourly (see data set AWT02). Data is dumped at approximately one to two week intervals from the CR-21X memory to cassette tape, which is later read into an IBM PC via Campbell tape reader card (Model PC201), reformatted, and written onto floppy disk. A computer program is used to reduce and summarize the five minute values into daily summary values and stormflow summary statistics. Detailed instructions for programming the CR-21X, dumping data to tape, and reading the tape into the microcomputer are presented in the CR-21X reference manual in Bushnell Rm 205.
METHODS
Gage height is sensed by pressure transducers (Druck Model PDCR 10/D) and recorded on the CR-21X. Conversion to stream discharge requires:
1) correction of measured gage height to actual gage height using direct measurements of stage made at least weekly at reference points at each flume, see APPENDIX C for instructions on how to correct the measured gage height.
2) translating gage height to stream discharge using a rating curve.
Two rating curves employ geometric relationships which are assumed to be valid at certain stage heights. The relationship used for calculating discharge at gage heights > 18.25 cm is: Qm3/s = 4.64 x 10-5 * s2.587 The relationship used for calculating discharge at gage heights between 0-18.25 cm is: Qm3/s = 6.49 x 10-5 * s2.4714 Where Q is discharge in cubic meters per second and s is gage height in cm. These equations were derived using procedures in Replogle, J. A., H. Reikerk, and B. F. Swindel. 1978. Water monitoring in coastal forest watershed studies. IMPAC Report 2, Vol. 3, No. 2. Southwestern Forest Expt. Station, USDA, Gainesville, Florida.
FORM OF DATA OUTPUT
Tapes are dumped every one to two weeks. Detailed instructions can be found in the CR-21X manual located in Bushnell Rm 205. A separate cassette tape is used for each station and a log book with information of each tape dump is located in Bushnell Rm 209.
Detailed instructions for retrieving stream data, entering time and date, changing batteries, etc. are located in Bushnell Rm 209 in the "Original of Field Notes" and "Copy of Field Notes for Field Use," files.
Once corrected (see APPENDIX C), data is stored on the LTER network. Daily and storm flow (five minute value) summaries are available.
