Delta-X: In Situ Water Quality Indicators across MRD, LA, USA, 2021

This dataset provides in situ measurements of water temperature (degrees Celsius), salinity (PSU), turbidity (FNU), chlorophyll-a fluorescence (micrograms per liter) in surface waters (~0.5 m). Measurements were made in the Atchafalaya and Terrebonne Basins from March 25th to April 22nd, 2021 as part of the Spring Delta-X campaign. During the field campaign, measurements were collected in multiple channels of varying width (from a few meters to >100m), near Delta-X intensive study sites, and in open bays and lakes and at few locations in the nearshore Gulf of Mexico. For each in situ collection, the measurements were collected using YSI ProDSS water quality probe.

This dataset includes 1 file in comma-separated values (*.csv) format. 

The QA and documentation of this dataset is in progress.

The Delta-X mission is a 5-year NASA Earth Venture Suborbital-3 mission to study the Mississippi River Delta in the United States, which is growing and sinking in different areas. River deltas and their wetlands are drowning as a result of sea level rise and reduced sediment inputs. The Delta-X mission will determine which parts will survive and continue to grow, and which parts will be lost. Delta-X begins with airborne and in situ data acquisition and carries through data analysis, model integration, and validation to predict the extent and spatial patterns of future deltaic land loss or gain.

File Naming Convention :

DeltaX_WaterQualityIndicators_[CAMPAIGN].csv [CAMPAIGN] refers to the field campaign (e.g., “Spring_2021”)

Parameters or variables provided in the dataset

Variable	Units of measurement	Description	Collected during the Pre-Delta-X campaign?
basin	N/A	“Atchafalaya” or “Terrebonne”	Yes
site_id	N/A	Name of site	No
campaign	N/A	e.g. Spring_2021	No
latitude	Decimal degrees	Latitude of sampling location	No
longitude	Decimal degrees	Longitude of sampling location	No
date	YYYY-MM-DD	Date of sampling and measurement	No
time	HH:MM:SS	UTC time of sampling	No
depth	meters	Depth of sampling	No
turbidity	FNU	average turbidity	No
standard_deviation_of_turbidity	FNU	Standard deviation of turbidity	No
salinity	PSU	average salinity	No
standard_deviation_of_salinity	PSU	Standard deviation of salinity	No
temperature	oC	average temperature	No
standard_deviation_of_temperature	oC	Standard deviation of temperature	No
chlorophyll_a_fluorescence	µg L-1	average chlorophyll-a fluorescence	No
standard_deviation_of_chlorophyll_a_fluorescence	µg L-1	Standard deviation of chlorophyll-a fluorescence	No

 

During the Delta-X Campaigns, in situ measurements of water temperature (^oC), salinity (PSU), turbidity (FNU), chorophyll-a fluorescence (µg L^-1) in surface waters were collected at a number of sites across the Atchafalaya and Terrebonne basins. These sites spanned large and small channels at locations chosen to cover a representative range of suspended solids concentration from a variety of hydrodynamic and physical settings typically encountered across the Atchafalaya and Terrebonne basins. This dataset is used to inform and validate Delta-X’s sediment transport models. These measurements made at discrete locations are paired with other measurements of total suspended sediment concentration made on discrete water samples, and are paired with other measurements of in situ beam attenuation coefficient at 670 nm, average suspended particle size, suspended particle size distributions, and in situ and airborne water reflectance (all provided as separate data sets). These location- and time-specific measurements are compared to numerical models to calibrate and validate its parameters. The models quantify the mesoscale (i.e., on the order of 1 ha) patterns of soil accretion that control land loss and gain and predict the resilience of deltaic floodplains under projected relative sea-level rise. Understanding and mitigating the impact of the relative sea-level rise on coastal deltas is urgent. If ignored, relative sea-level rise will very soon have devastating consequences on the livelihood of the half-billion people that live in these low-lying coastal regions.

The ProDSS was calibrated for conductivity at the beginning of the campaign and for turbidity every two weeks using the calibration solution recommended and sold by YSI®. The turbidity was calibrated using Milli-Q water (for 0 FNU) and a formazin solution of 124 FNU recommended by YSI, which bracketed the range of turbidity observed in the study area. The chlorophyll-a fluorescence provided here are only calibrated with Milli-Q water in order to zero the instrument. The instrument was pressure-tared on the boat deck before deployment. The instrument was lowered from the side of the boat and the data was collected at the surface for about two minutes at a rate of 1 Hz. The data from the two-minute recording was averaged and a standard deviation of the measurements was calculated.

Sampling Procedure

Each in situ measurement was collected directly by lowering the ProDSS water-quality probe from the side of the boat and keeping it submerged at about 0.5 m beneath the surface (Figure 1). Measurements were collected at a rate of 1 Hz for a duration of about two minutes before retrieving the instrument. Data from the ProDSS were then retrieved and exported as individual casts using the commercial YSI® KorDSS software. Each cast was then processed in MATLAB® to generate the products of interest including: water temperature (^oC), salinity (PSU), turbidity (FNU), chlorophyll-a fluorescence (µg L^-1). In the processing, the measurements collected at the surface for about two minutes were averaged and the standard deviation was calculated.

Study Sites

The Spring 2021 campaign collected measurements from the ProDSS at different locations across the Atchafalaya and Terrebonne Basins (Figure 2). Each sampling site was named using a combination of abbreviations provided in Table 1 as follows: BBB_MMDD_TN where BBB is the abbreviation for the basin (WLD or TB), MMDD is the month and day of 2021 (e.g., 0327 for March 27, 2021), T is the abbreviation for the station type (F for Full station, D for Dry station, and B for Basic station), and N is the sequential number of the station of each type sampled that day (B1 for first basic station, S1 for first full station, S2 for second full station, etc.).

Figure 2: Water-quality indicators measurement sites for the Spring 2021 Delta-X campaign.

Table 1: YSI ProDSS site naming

Abbreviated Site name	Full Site name
WLD	Atchafalaya Basin (including Wax Lake Delta)
TB	Terrebonne Basin
S	Full station (Water samples for TSS was collected along with water reflectance, measurements from the LISST, and water-quality indicators from ProDSS probe)
D	Dry stations (No Water samples for TSS was collected, but measurements of water reflectance, from the LISST, and water-quality indicators from ProDSS probe were collected)
B	Basic station (only measurements of LISST, and water-quality indicators from ProDSS probe were collected)