| Description |
This data provides river turbidity measurements collected on the Carmel River, CA. Turbidity was measured to study any changes in the Carmel River’s sediment loads following the removal of the San Clemente Dam. The USGS-run DTS-12 turbidity sensor was deployed above the Sleepy Hollow Weir on the Carmel River, CA (instrument was located at 36.445250 degrees North, 121.710494 degrees West). Deployment began on December 9, 2014. After June 16, 2016, the instrument was removed for calibration. A new instrument was re-deployed on October 14, 2016, and continued to record until recovery on July 13, 2017. Due to the instrument removal and calibration, there exists an approximately 4-month long gap in data collection from June 16 to October 14, 2016. The sensor recorded turbidity, water temperature, and battery voltage at 15-minute intervals. The data are in Formazin Nephelometric Units (FNU), which are similar to Nephelometric Turbidity Units (NTU) in that both measure scattered light at 90 degrees from the incident light beam. FNU are measured with an infrared light source (by the ISO 7027 method), whereas NTU requires a white light source (EPA method 180.1). For more information on FNU and water turbidity data, please visit http://or.water.usgs.gov/grapher/fnu.html. Apparently spurious data points were removed during processing. Those included: data points in which the temperature reading dropped abruptly to zero [both temperature and turbidity values were set to "NaN" (Not A Number)], data points in which the turbidity value abruptly dropped from a non-zero value to zero and recovered immediately to near the original non-zero reading (in which case turbidity, but not temperature, values were set to "NaN"), and several points were deleted in the record in which turbidity spiked rapidly by two or three orders of magnitude and then immediately returned to much lower values. This may occur, for example, if a leaf blocked the sensor momentarily, but we considered it was likely not a real increase in turbidity. Several rapid apparent increases in turbidity remain in the record. These may be real or spurious; they did not appear abrupt enough to be clearly spurious, and so are left in the record. Turbidity spikes were also removed that coincided with equipment deployment at the site. [More]
|
