Water Engagement Roundup
The topic for the Water Engagement Roundup webinar recorded on Wednesday 21 August 2024 was the department's work under the Hydrometric Networks and Remote Sensing Program.
Watch the webinar
Wednesday, 21 August 2024. This month, the topic the department's work under the Hydrometric Networks and Remote Sensing Program.
Questions and answers
What is the cost and accuracy of satellite compared to traditional monitoring and camera/AI monitoring?
A. Satellite data from Landsat (US Space Agency) and Sentinel (European Space Agency) is free to access and publicly available. This imagery is often supported by data captured by aerial survey (plane/drone) acquired by Government departments to for many purposes, using government owned sensors and platforms or via private sector, compared to traditional gauging / insitu monitoring.
How would we use the irrigation tool?
A. Currently the tools are internally focused, as demonstrated in the presentation. We are working toward public release of timeseries data in the near future.
How much to these programs extend into the coastal catchments?
A. The HNRS Program was focused on the Northern Murray Darling Basin (MDB) so did not extend to the coastal catchments. We are extending the same method and learnings to coastal catchments and many of the other HNRS products are being extended to the rest of the state beyond the Northern MDB.
If satellite imagery is so accurate, why do irrigators need to spend tens of thousands of dollars on storage meters for floodplain harvesting compliance?
A. Satellite imagery is not as accurate as in situ sensors and provides measurements at a lower temporal resolution. Satellite sensing will never be so precise that it can replace on-ground measurements. Satellite sensors are good as a mass screening tool. It provides wide, repetitive coverage, cost effective for large scale monitoring, near real time data and ability to capture data beyond human eye into different parts of the electromagnetic spectrum. Its ability to provide long term monitoring is very important to understand environmental phenomena.
Does the Hydrometric Networks and Remote Sensing Program (HNRS) differ from the CSIRO's AquaWatch Mission? Is there hardware/technology shared between the program and mission?
A. HNRS had wider scope than Remote Sensing of water quality. We are keeping in touch with AquaWatch team to find synergies and may use the platform in future.
Were you using the DEA Landsat data products for building timeseries, or directly accessing the data via AWS/NASA repositories?
A. In the past we used DEA data cube. There is a time lag between the capture and availability of data. We have moved to Google Earth Engine and images are now available within 24 hours.
With regard to the LiDAR data that will become available through ELVIS, is this free or are there cost-recovery measures being used to recoup the costs of the data collection?
A. ELVIS portal allows access of Lidar and its free. Visit www.elvis.fsdf.org.au
Would it be feasible to use GEDI to estimate volume for water storages that you do not have higher fidelity 3D data for?
A. We have not tested using GEDI to estimate storage volume curves, but the spatial resolution of 30m is not sufficient to resolve the bathymetry of these storages.
Have you been able to test/validate the Area-Volume relationship methodology through any ground-truthing approach?
A. We have not compared with ground measurements yet. However, we are in the process of undertaking in situ measurements and comparing with remote sensing output. However area to volume (and AHD) was validated by survey during development of entitlement and FPH policy.
Will this work expand into other catchments at some stage? through another process?
A. That is certainly the plan. Our funding under the HNRS project was tied to the northern basin but there is little reason why with similar available base data and thresholds customised to southern or coastal (with a few other considerations) catchments it would not be as effective.
To calculate the storage curve do you assume that all parts of the storage have the same water level even if they can be disconnected?
A. Depending on the storage there may be two or more curves to account for connected infrastructure.
Have you come across the 30 m monthly CMRSET evapotranspiration dataset in Google Earth Engine? It can be used to estimate irrigation evapotranspiration and evaporation loss from the storages.
A. Yes we are active users of the CMRSET ET dataset in GEE! We use it as an additional line of evidence when mapping irrigated areas from NDVI.
How accurate is the bed level estimates in the on-farm storage and how is uncertainty accounted for in depth estimates and corresponding volume (where LiDAR cannot penetrate due to minimum pool levels in the storages and bed levels change over time)?
A. Flown when dry as a preference, assumed where not possible on account of other factors. Under FPH policy licence owners responsible for updating their curves as storages change.
Do you make any attempt to correlate the data you have derived with the consumption of water as recorded by meters?
A. Yes, NRAR is using this data to monitor and compare metered water use across the FPH properties in the Northern Basin. This mass screening tool allows NRAR to efficiently identify potential noncompliance issues.
I assume we will look at validating these estimates with real data extracted from field and look at tuning the models?
A. This is a plan for the future and is in the workplan.
Once initial depth of a storage is mapped, and once monitoring of a sight has been triggered, will volume of a full storage be accurate if the basin floor has been changed?
A. Flown when dry as a preference, assumed where not possible on account of other factors. Under FPH policy licence owners responsible for updating their storage curves.
Will the technology be applied to the detection of illegal or unlicensed storages?
A. Yes actively used in compliance matters.
I would like to know if you also calculate the area-volume relationship for the wetlands in the Basin?
A. Yes, evolving space but are actively looking to apply to wetlands and other waterbodies. We have not developed storage capacity curves for wetlands. There is a possibility in future we may derive area-volume relationship from DEM for wetlands.