YSI 6200 data sondes were deployed vertically in a pool deep enough to contain water during dry conditions. The sonde was deployed in a PVC tube, which was attached to ree-bar driven into the stream bed. The PVC tube had holes drilled to allow adequate water circulation. Dissolved oxygen measurements are of good quality because detritus did not accumulate in the bottom of the pool (unlike our suburban site).

The PVC tube was surveyed upon original deployment in 2001 and resurveyed in 2002 to ensure that elevation did not change during winter ice period. No change was detected. No evidence of change has been noted through 2006 based on discharge measurements. See discussion below for development of the discharge-stage relationship.

Recalibration of oxygen, pH, conducitivty and depth was performed roughly every 4-6 weeks. Instrument drift during deployment periods was not significant.

ADDITIONAL RESEARCH LOCATION COORDINATES: In addition to the decimal degree coordinates given above, locations are also given here in Massachusetts State Plane coordinates. The stream is called Cart Cr. and is located in Newbury MA. Some residential area is present. (~ 10% of the basin). In addition, I-95 passes through the center of the catchment, resulting in roughly 8% impervious surface area

STATION STATE X STATE Y
YSI-CC 247680 946790

NOTES AND COMMENTS:

Velocity measurements were made using a Marsh McBirney current meter. Discharge estimates in Cart Cr. are based on a power rating curve that contains measurements up to a depth of 0.8 meters, as standardized to depth measured with a HOBO datalogger (Column = HOBO_Depth), which is above bankfull stage. Rating curve has been standardized to HOBO_Depth to allow application of a single rating curve across years. Rating curve has an R2 of 0.96 using 32 measurements between 2001 and 2007. All files in this series (2001-2006) are currently standardized to HOBO_depth.

This file includes a column called OLD-Discharge, which uses an earlier rating curve with fewer points, a smaller range of depth. This is maintained for comparison with the new and improved rating curve. The column Depth_Device is included when combining files from several years, over which several different devices were used to calculate depth. HOBO_Depth is the depth that is standardized across all measurement devices so that a single rating curve can be applied.

CALCULATIONS:
Discharge rating curve :
Discharge (l/s) = 731.91 (depth) ^ 5.5172
where depth is HOBO_Depth

OLD RATING CURVE ( prior to Sept 2007 revision):
Discharge measurements in Cart Creek are based on an exponential rating curve that contains measurements up to a depth of 0.475m (Using the column YSI_Depth). Flows above this amount are estimated using a linear extrapolation using the six measurements with the highest flow. Thus flows determined from levels greater than 0.475m are approximate (0 % of the readings in 2001 deployment period). Rating curve below 0.475m is based on an exponential relationship with an R2 = 0.99. Measurements are based on 17 measurements taken between 2001 and 2003.

OLD CALCULATIONS (NO LONGER USED):
When stage in Cart Cr. is less than 0.475m :
Discharge (l/s) = 0.2481 * 2.71828 ^ (12.389 * depth)

When stage in Cart Cr. is greater than 0.475m :
Discharge (l/s) = 629.7 * depth – 212.8

where depth = YSI_Depth