Estimated Sediment Loads and Gully Runnoff for Restoration Effectiveness (NESP TWQ 2.1.4, CSIRO)

This dataset contains preliminary estimates of discharge and loads (Total suspended sediment and total nitrogen) based on monitoring data collected for the NESP Project 2.1.4 Demonstration and evaluation of gully remediation on downstream water quality and agricultural production in GBR rangelands.

The data in presented in this metadata are part of a larger collection and are intended to be viewed in the context of the project. For further information on the project, view the parent metadata record: Demonstration and evaluation of gully remediation on downstream water quality and agricultural production in GBR rangelands (NESP TWQ 2.1.4, CSIRO).

Monitoring of these sites is continuing as part of NESP TWQ Project 5.9. Any temporal extensions to this dataset will be linked to from this record.

Methods:
To estimate loads of suspended sediment (TSS) and total nitrogen (TN) the following steps were undertaken:
(1) Depth, velocity and RTK surveyed cross-sectional area data were used to generate a stage-discharge rating curve for each site;
(2) Linear relationships between TSS and TN sample concentrations and coincident turbidity data were derived for all sites (Table 6). Turbidity data was not used when (i) the instrument exceeded the instrument calibration threshold; (ii) turbidity sensor readings were erroneous due to damage or sensor malfunction, or when the sensors were buried. These relationships allowed for estimation of TSS and N from turbidity. When there was no turbidity data (due to sensor issues or instrument burial), TSS and TN concentrations were infilled using sample interpolation.
(3) Total suspended sediment (TSS) and total nitrogen (TN) loads were then generated for each event and each water year (generally Nov to April) by multiplying discharge by concentration.
(4) For all sites flow weighted annual average mean concentrations (FWAAC) were generated by dividing the annual load by annual runoff. This provided a quick visual assessment of the relative change in concentration between sites.
(5) For some sites (i.e. Mt Wickham) event mean concentrations (EMCs) were generated for individual events by dividing the event load by event runoff. This provided a flow weighted mean concentration for each event. The event mean concentration (EMC) value for each event and year was calculated using mass of the sediment (in tonnes) divided by the runoff volume (in ML) during the time interval (T) (after Kim et al., 2004).

Limitations of the Data:
This dataset contains Water Quality monitoring data collected at these gully sites for the three reporting wet seasons spanning June-July 2016-2017, 2017-2018 and 2018-2019. During this study, the project had challenges with (i) sensor malfunctions (ii) sensor burial and re-scour (iii) sensors being damaged by moving objects (iv) green ant nests in sensors and (v) wires chewed by livestock. In addition sampling error or uncertainty in the discharge and load calculations can be high in semi-arid systems (Kuhnert et al., 2012). Consequently, all runoff and loads estimates are considered preliminary and will likely change in subsequent reporting years.

Format:
This data collection consists of 5 zip files (one for each paired gully monitoring site). Zip files are named according to the property on which they are located. Each zip file contains eight to twelve MS Excel spreadsheets representing daily and annual discharge and load estimates for both the Control and Treatment gully sites.

MS Excel files contain tabs representing the following:
SETUP – contains the site specific parameters used to estimate discharge and loads such as catchment size, location of instruments relative to depth sensor or gully cross section, discharge rating curve, and constituent-turbidity relationship
SUMMARY – provides annual totals for rainfall, runoff, and loads, daily rainfall runoff chart, summary tables of rainfall and runoff events.
RUNOFF_LOADS_CHART – chart of timeseries of depth, event depth, TSS or N concentration (as estimate from turbidity) and sample concentration - used to check for issues with depth or turbidity when interpreting annual or daily totals
DAILY_SUMMARY_ALL_DATES – for generating daily rainfall, runoff and load estimates
SAMPLES – list of sample values relevant to loads sheet period for cross checking against turbidity relationship
RUNOFF LADS CALCS ALL TIMESTEP - raw Stream data with associated instantaneous calculations of discharge and loads
RAIN AT GAUGE – rainfall timeseries from site (or closest) gauge
RAIN USED FOR AVERAGING – if catchment is large, a second rain gauge may be used for averaging (not usually for gullies)

Data Dictionary:

Column headings used in the Excel spreadsheets:
Timestamp – time in AEST (+10GMT)
Depth – Depth of flow above depth sensor in millimetres, Depth sensor was level with gully bed at time of installation.
Turbidity or Turb – turbidity in units of NTU
(note that the Turbidity and velocity sensors are mounted above the depth sensor by 100 mm or more).
Rainfall – rainfall in millimetres
Discharge – discharge as either a rate or a total volume of water
Runoff – discharge divided by catchment area
Sample – Sample Number as submitted to Lab
TSS / N = Total Suspended Sediment / Total Nitrogen

Site_Code used for file names is as follows:
MIV = Minnievale
MV = Meadowvale
MW = Mount Wickham
SB = Strathbogie
VP = Virginia Park
<T/C> - Treatment/Control
Note:
SBT is now the Strathbogie Control site
SBC (to 2018) and SBT2 (after 2018) is now the Strathbogie Treatment site

References:

Bartley, Rebecca; Hawdon, Aaron; Henderson, Anne; Wilkinson, Scott; Goodwin, Nicholas; Abbott, Brett; Baker, Brett; Matthews, Mel; Boadle, David; Jarihani, Ben (Abdollah). (2018) Quantifying the effectiveness of gully remediation on off-site water quality: preliminary results from demonstration sites in the Burdekin catchment (second wet season). RRRC: NESP and CSIRO. csiro:EP184204.

Baker, B., Hawdon, A. and Bartley, R., 2016. Gully remediation sites: water quality monitoring procedures, CSIRO Land and Water, Australia.

eAtlas Visualisation
The visualisation presented on the eAtlas maps is a derived product of the summary data found within this data collection. A summary dataset was created using information presented on each spreadsheet [Water-Year, Site, Catchment Area, Rainfall, Runoff, %Runoff, Total TSS Load, Average TSS from time series, Total N Yield, N Loss, Average B from timeseries]. Two additional columns were added to the core information: data infill as referenced in the spreadsheets, has been represented in column 'Contains_Infilled_Data' noting Y or N; column 'Treatment_Control' was added to the summary dataset to aid visual representation, where treatment 'T' and control 'C' sites clearly identified.

Data Location:

This dataset is filed in the eAtlas enduring data repository at: data\nesp2\2.1.4_Gully-remediation-effectiveness