Water-level, wind-wave, and suspended-sediment concentration (SSC) time-series data from Little Holland Tract (station HWC), Sacramento-San Joaquin Delta, California, 2015-2017

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Frequently anticipated questions:

What does this data set describe?
Who produced the data set?
Why was the data set created?
How was the data set created?
How reliable are the data; what problems remain in the data set?
How can someone get a copy of the data set?
Who wrote the metadata?

What does this data set describe?

Title:

Water-level, wind-wave, and suspended-sediment concentration (SSC) time-series data from Little Holland Tract (station HWC), Sacramento-San Joaquin Delta, California, 2015-2017

Abstract:

Water depth and turbidity time-series data were collected in Little Holland Tract (LHT) from 2015 to 2017. Depth (from pressure) was measured in high-frequency (6 or 8 Hz) bursts. Burst means represent tidal stage, and burst data can be used to determine wave height and period. The turbidity sensors were calibrated to suspended-sediment concentration measured in water samples collected on site. The calibration and fit parameters for all of the turbidity sensors used in the study are tabulated and provided with the data. Data were sequentially added to this data release as they were collected and post-processed. Typically, each zip folder for a deployment period contains one file from an optical backscatter sensor and two files of data from a bursting pressure sensor.

Supplemental_Information:

How might this data set be cited?
Lacy, Jessica R., Joanne C. T. Ferreira, and Carlson, Emily M., 2016, Water-level, wind-wave, and suspended-sediment concentration (SSC) time-series data from Little Holland Tract (station HWC), Sacramento-San Joaquin Delta, California, 2015-2017: data release DOI:10.5066/F73R0R07.
Online Links:
- https://doi.org/10.5066/F73R0R07
- https://www.sciencebase.gov/catalog/item/5b9845fbe4b0702d0e842612
This is part of the following larger work.
Lacy, Jessica R., Carlson, Emily M., and Joanne C. T. Ferreira, 2016, Wind-wave and sediment-transport time-series data from Liberty Island and Little Holland Tract, Sacramento-San Joaquin Delta, California. 2015-2017: data release DOI:10.5066/F73R0R07, U.S. Geological Survey, Coastal and Marine Geology Program, Pacific Coastal and Marine Science Center, Santa Cruz, California.
Online Links:
- https://doi.org/10.5066/F73R0R07
What geographic area does the data set cover?
West_Bounding_Coordinate: -121.6917
East_Bounding_Coordinate: -121.6533
North_Bounding_Coordinate: 38.32737
South_Bounding_Coordinate: 38.24528
What does it look like?

https://www.sciencebase.gov/catalog/file/get/5b9845fbe4b0702d0e842612?name=2018_locus_map.png&allowOpen=true (PNG)
Map of Liberty Island and Little Holland Tract in the Sacramento-San Joaquin Delta showing locations of sampling stations.
Does the data set describe conditions during a particular time period?

Beginning_Date: 07-Dec-2015

Ending_Date: 03-Oct-2017

Currentness_Reference:

ground condition at time data were collected
What is the general form of this data set?
Geospatial_Data_Presentation_Form: NetCDF files
How does the data set represent geographic features?
1. How are geographic features stored in the data set?
  This is a Point data set.
2. What coordinate system is used to represent geographic features?
How does the data set describe geographic features?
Entity_and_Attribute_Overview:
NetCDF files are self-contained and attribute information may be found in the header of the file itself.
Entity_and_Attribute_Detail_Citation:
The entity and attribute information was generated by the individual and/or agency identified as the originator of the data set. Please review the rest of the metadata record for additional details and information.

Who produced the data set?

Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
- Jessica R. Lacy
- Joanne C. T. Ferreira
- Emily M. Carlson
Who also contributed to the data set?
To whom should users address questions about the data?

PCMSC Science Data Coordinator

U.S. Geological Survey, Pacific Coastal and Marine Science Center

2885 Mission Street
Santa Cruz, CA

USA

831-427-4747 (voice)

pcmsc_data@usgs.gov

Why was the data set created?

These data will be used to determine the range of turbidity and suspended-sediment concentration (SSC) in Little Holland Tract and the extent to which wind waves contribute to turbidity, to investigate physical attributes of flooded habitats that promote enhanced turbidity, and to evaluate the potential for flooded agricultural tracts to contribute to elevated turbidity in adjacent waters.

How was the data set created?

From what previous works were the data drawn?
IEM (source 1 of 1)
The Iowa Environmental Mesonet (IEM), 2016, ASOS-AWOS-METAR Data Download: Iowa State University, Ames, IA.
Online Links:
- https://mesonet.agron.iastate.edu/request/download.phtml?network=CA_ASOS#
Type_of_Source_Media: Digital Resources
Source_Contribution:
Source information used in support of the development of the dataset. Local atmospheric readings were obtained from the IEM database to use during post-processing of the data to adjust for local atmospheric deviations.
How were the data generated, processed, and modified?

Date: 07-Dec-2015 (process 1 of 20)
Instruments included in deployment are: RBR duo bursting pressure sensor, and RBR virtuoso turbidity meter.
Date: 04-Feb-2016 (process 2 of 20)
Instruments were retrieved and replaced with identical instruments and programing in order to refresh memory space and battery life. The data from the retrieved instruments were post-processed and sequentially added to this data release.
Date: 12-Apr-2016 (process 3 of 20)
Instruments were retrieved and replaced with identical instruments and programing in order to refresh memory space and battery life. The data from the retrieved instruments were post-processed and sequentially added to this data release.
Date: 08-Jun-2016 (process 4 of 20)
Instruments were retrieved and replaced with identical instruments and programing in order to refresh memory space and battery life. The data from the retrieved instruments were post-processed and sequentially added to this data release.
Date: 09-Aug-2016 (process 5 of 20)
Instruments were retrieved and replaced with identical instruments and programing in order to refresh memory space and battery life. The data from the retrieved instruments were post-processed and sequentially added to this data release.
Date: 12-Oct-2016 (process 6 of 20)
Instruments were retrieved and replaced with identical instruments and programing in order to refresh memory space and battery life. The data from the retrieved instruments were post-processed and sequentially added to this data release.
Date: 07-Dec-2016 (process 7 of 20)
Instruments were retrieved and replaced with identical instruments and programing in order to refresh memory space and battery life. The data from the retrieved instruments were post-processed and sequentially added to this data release.
Date: 30-Jan-2017 (process 8 of 20)
Instruments were retrieved and replaced with identical instruments and programing in order to refresh memory space and battery life. The data from the retrieved instruments were post-processed and sequentially added to this data release.
Date: 07-Feb-2017 (process 9 of 20)
Data were accumulated into NetCDF files. During post-processing, data collected when instruments were out of the water, and data degraded by biological fouling, were removed from the time series. Bad data points were identified by 1) the deployment and recovery times; 2) pressure readings equal to or less than 3 cm of water; and, 3) amplitude or correlation values outside of predetermined quality thresholds for the velocimeter. Pressure data were adjusted from absolute pressure to hydrostatic pressure by removing local atmospheric pressure. Local atmospheric pressure was obtained from IEM for the Travis Air Force Base (SUU) station, which is located 15 miles from the study site.
Date: 07-Feb-2017 (process 10 of 20)
Optical backscatter (OBS) data were put through a rigorous cleaning process, as these types of data are inherently noisy. First, the data were inspected for extended periods of time (typically many days) of unrealistic values that did not follow typical trends. These periods of bad data, believed to be caused by vegetation blocking the sensor, were manually removed from the time series. Second, large values of the first derivative of the time series were removed, which indicate unrealistic single point spikes in the data. Spikes were identified by change thresholds of +/-70 mg/L for the burst-average time series and +/-1 mg/L within the bursts. Third, readings above 90 percent of the maximum instrument voltage were removed. In particularly noisy data, points deviating more than 3 standard deviations from the running mean were removed. Finally, 'island' points were identified (and removed) by checking for real-value points with both neighbors flagged as bad. Bad data points were then replaced by linear interpolation, except for the large chunks that were removed in the first step of filtering. The OBS data were converted to suspended-sediment concentration using calibration constants derived from linear regression between OBS data and sediment concentration measured in water samples collected in the study area.
Date: 07-Feb-2017 (process 11 of 20)
Files were named with a convention that uses a 13-digit alpha-numeric code. The first two characters for this dataset are all 'DL' for the experiment name. For deployments 1 - 9, the third character is a number indicating which deployment period the data comes from (1, 2, 3, etc.); the fourth and fifth positions represent the calendar year in which the first data point in the file was taken (15, 2015; 16, 2016). Deployments 10 to 13 occurred during the year 2017. In these cases, the third and fourth character indicates the deployment number while a '7' in the fifth position represents calendar year. The sixth position is a letter indicating the water body/region (L, Liberty Island; H, Little Holland Tract). The seventh position is a letter representing the station type (V, velocity station; W, wind-wave station). The eighth position represents the location of the station (A, B, C, etc.) within the water body/region. Next is a three-character code for the instrument type (vec, Nortek's Acoustic Doppler Velocimeter; rbr, RBR's bursting pressure sensor; ctd, RBR's CTD; vir, RBR's Virtuosos turbidity sensor). There are an additional two characters for the instruments that collect in a bursting pattern to indicate if the burst is included in the file or the statistics of the burst, this indicator is omitted if there is no bursting pattern (-b, burst; -s, statistics).
Date: 30-Mar-2017 (process 12 of 20)
Instruments were retrieved and replaced with identical instruments and programing in order to refresh memory space and battery life. The data from the retrieved instruments were post-processed and sequentially added to this data release.
Date: 31-May-2017 (process 13 of 20)
Instruments were retrieved and replaced with identical instruments and programing in order to refresh memory space and battery life. The data from the retrieved instruments were post-processed and sequentially added to this data release.
Date: 08-Dec-2022 (process 14 of 20)
Instruments were retrieved and replaced with identical instruments and programing in order to refresh memory space and battery life. The data from the retrieved instruments were post-processed and sequentially added to this data release.
Date: 03-Oct-2017 (process 15 of 20)
Instruments were retrieved. The data from the retrieved instruments were post-processed and sequentially added to this data release.
Date: 06-Aug-2018 (process 16 of 20)
Data were accumulated into NetCDF files. During post-processing, data collected when instruments were out of the water, and data degraded by biological fouling, were removed from the time series. Bad data points were identified by 1) the deployment and recovery times; 2) pressure readings equal to or less than 3 cm of water; and 3) amplitude or correlation values outside of predetermined quality thresholds for the velocimeter. Pressure data were adjusted from absolute pressure to hydrostatic pressure by removing local atmospheric pressure. Local atmospheric pressure was obtained from IEM for the Travis Air Force Base (SUU) station, which is located 15 miles from the study site.
Date: 06-Aug-2018 (process 17 of 20)
Optical backscatter (OBS) data were put through a rigorous cleaning process, as these types of data are inherently noisy. First, the data were inspected for extended periods of time (typically many days) of unrealistic values that did not follow typical trends. These periods of bad data, believed to be caused by vegetation blocking the sensor, were manually removed from the time series. Second, large values of the first derivative of the time series were removed, which indicate unrealistic single point spikes in the data. Spikes were identified by change thresholds of +/-70 mg/L for the burst-average time series and +/-1 mg/L within the bursts. Third, readings above 90 percent of the maximum instrument voltage were removed. In particularly noisy data, points deviating more than 3 standard deviations from the running mean were removed. Finally, 'island' points were identified (and removed) by checking for real-value points with both neighbors flagged as bad. Bad data points were then replaced by linear interpolation, except for the large chunks that were removed in the first step of filtering. The OBS data were converted to suspended-sediment concentration using calibration constants derived from linear regression between OBS data and sediment concentration measured in water samples collected in the study area.
Date: 06-Aug-2018 (process 18 of 20)
Files were named with a convention that uses a 13-digit alpha-numeric code. The first two characters for this dataset are all 'DL' for the experiment name. For deployments 1 - 9, the third character is a number indicating which deployment period the data comes from (1, 2, 3, etc.); the fourth and fifth positions represent the calendar year in which the first data point in the file was taken (15, 2015; 16, 2016). Deployments 10 to 13 occurred during the year 2017. In these cases, the third and fourth character indicates the deployment number while a '7' in the fifth position represents calendar year. The sixth position is a letter indicating the water body/region (L, Liberty Island; H, Little Holland Tract). The seventh position is a letter representing the station type (V, velocity station; W, wind-wave station). The eighth position represents the location of the station (A, B, C, etc.) within the water body/region. Next is a three-character code for the instrument type (vec, Nortek's Acoustic Doppler Velocimeter; rbr, RBR's bursting pressure sensor; ctd, RBR's CTD; vir, RBR's Virtuosos turbidity sensor). There are an additional two characters for the instruments that collect in a bursting pattern to indicate if the burst is included in the file or the statistics of the burst, this indicator is omitted if there is no bursting pattern (-b, burst; -s, statistics).
Date: 07-Oct-2019 (process 19 of 20)
Corrected the original publication date for Citation and for Larger Work Citation to conform to new guidance issued regarding data release revisions. For information regarding the original version of this data release, see Point of Contact section of this metadata file. Person who carried out this activity:

Susan A Cochran

U.S. Geological Survey, Pacific Coastal and Marine Science Center

2885 Mission St.
Santa Cruz, CA

United States

831-460-7545 (voice)

scochran@usgs.gov

Date: 19-Oct-2020 (process 20 of 20)
Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed. Person who carried out this activity:

U.S. Geological Survey

Attn: VeeAnn A. Cross

Marine Geologist

384 Woods Hole Road
Woods Hole, MA

508-548-8700 x2251 (voice)

508-457-2310 (FAX)

vatnipp@usgs.gov
What similar or related data should the user be aware of?
Snyder, Alex G, Stevens, Andrew W, Carlson, Emily M, and Lacy, Jessica R, 2016, Digital elevation model of Little Holland Tract, Sacramento-San Joaquin Delta, California, 2015: data release doi:10.5066/F7RX9954, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, California.
Online Links:
- http://dx.doi.org/10.5066/F7RX9954

How reliable are the data; what problems remain in the data set?

How well have the observations been checked?
No formal attribute accuracy tests were conducted.
How accurate are the geographic locations?
A formal accuracy assessment of the horizontal positional information in the data set has either not been conducted, or is not applicable.
How accurate are the heights or depths?
There are two sources of uncertainty associated with vertical positioning of the instruments: 1) the measuring tools used during instrument mounting; and, 2) the amount of settling that occurs during deployment. There was no evidence that the platforms settled to a large degree, they are easily lifted by one person, the sediment tends to be very compacted in the study area, and analysis of distance to bed data did not show gradients over the duration of deployment. The measuring tools used to mount the instruments onto the platforms have a resolution of 0.1 cm resulting in an uncertainty of 0.05 cm.
Where are the gaps in the data? What is missing?
Typically, except for times of instrument failure, each zip folder for a deployment period contains one file from an optical backscatter sensor and two files of data from a bursting pressure sensor. Data were sequentially added to this data release as they were retrieved and post-processed. Users are advised to read the metadata for each part of this data release carefully for additional details.
How consistent are the relationships among the observations, including topology?
Data fall within expected ranges.