Assessment of GRACE satellites for groundwater estimation in Australia
Project details
| Objective: |
To assess the reliability of a new approach to estimate groundwater at a national scale using GRACE satellites |
| Funding: |
$290,000 plus applicable GST |
| Jurisdiction: |
National |
| Commenced: |
June 2011 |
| Completion: |
December 2011 |
| Outputs: |
Waterlines 71: Assessment of GRACE satellites for groundwater estimation in Australia |
About the project
The GRACE (Gravity Recovery and Climate Experiment) satellites can detect small changes in the earth's gravity field. These changes can arise from a number of causes, including changes in the volume of groundwater.
Initial trials of GRACE in Australia as a tool to estimate groundwater showed promise and it was important to assess the accuracy of how the combination of GRACE and hydrology models track groundwater changes before this novel approach to groundwater monitoring could be considered for practical use.
This project systematically studied GRACE's ability to estimate variations in groundwater using a combination of space gravity and hydrological modelling.
The project objectives were to:
- provide a clear assessment of the reliability of GRACE satellites
- review the existing studies where GRACE satellite data has been applied to hydrology or groundwater estimation
- assess the strategies to analyse the available GRACE gravity fields and quantify how the differences affect estimates of hydrological processes in Australia by combining traditional water balance models with remote sensed data
- provide a groundwater change estimate across Australia, including an estimate of uncertainties
- assess if there is a homogeneous level of accuracy across the continent or whether there are regions in Australia that suffer from degraded accuracy. If the latter, investigate why this is the case
- familiarise hydrogeologists, groundwater managers and water accountants with this potential new information source on groundwater.
This project compared some of the different strategies that are used to interpret the GRACE satellite data to identify the most accurate strategy for estimating water changes.
The project deliverable was a Waterlines discussion paper.
Project benefits
This project assessed the reliability of a new, low cost approach to estimating groundwater that has the potential to complement traditional direct observations.
This project established:
- if this novel approach to groundwater monitoring can be considered for practical use
- the potential application of GRACE satellites to groundwater accounting and management.
Project outcomes
- The study found that further work is required before groundwater levels derived from GRACE satellite data can be reconciled with groundwater monitoring observations. Specific areas for further study include soil moisture storage modelling, techniques to convert GRACE satellite data into groundwater data, and greater granularity in groundwater monitoring or development of groundwater models at larger spatial scales.
- Likely causes for discrepancies include the large spatial scale in the GRACE estimates, inaccuracies in modelling soil moisture storage, inadequate techniques for converting groundwater levels to groundwater volumes, and poor spatial coverage of groundwater monitoring.