Future groundwater monitoring
Both Agriculture WA and the WRC carry out groundwater monitoring programs. In general terms, Agriculture WA (Catchment Hydrology Group) maintains groundwater data sets in agricultural areas on its AgBores database. These data are primarily used for salinity research. The WRC has some monitoring that falls into this category but is primarily concerned with monitoring potable/industrial groundwater resources. This arrangement is ongoing.
Over 5000 bores were interrogated for use in the Audit project. After removing bores with limited data, there are now 4780 bores available on the AgBores database available for future monitoring.
Agriculture WA has begun a census of bores currently monitored to determine those that should remain as priorities for long-term monitoring. An initial analysis has identified over 1400 bores that should receive priority to provide long-term groundwater trend data. The table below shows the distribution of these bores within zones used for analysis in the NLWRA along with those bores nominated as high priority long-term sites for Agriculture WA. There are two zones (241 and 243) that still require further analysis to determine which sites will provide the most representative long-term data.
Distribution of these bores within zones.
|Zone||Bores used in NLWRA||Bores Identified as long-term sites|
Analysis has shown that bores identified as long-term sites do not occupy all the systems analysed in this project. Some bore sites were not considered suitable for this purpose.
The findings in this report are based at a regional scale (1:100,000 to 1:250,000). Should future assessment be undertaken at a larger scale (e.g. farm scale, 1:10,000), improved geo-referencing of bore locations will also be necessary. It is recommended that GPS-based referencing of bore locations become standard procedure during site establishment.
This assessment has identified systems and zones lacking data. These areas have been used to prioritise sites for drilling programs initiated by Agriculture WA during 2000. These programs are designed to fill some of the gaps that exist in the current monitoring networks.
Systems identified at high risk due to shallow watertables in the future and which do not currently have sites suitable for long-term monitoring will be given priority in future drilling programs. This work will provide improved data for future Audits.
Data and information arising from this assessment
Future Audits assessing the impact of groundwater and salinity on infrastructure, biodiversity, water resources and agriculture should consider any implications and issues raised from this study that might limit or restrict any future assessment of impacts.
- Data sets for infrastructure need to be well maintained.
- To fully value the costs to infrastructure, improved dollar values of infrastructure are required.
- Data sets relating to biodiversity are still largely being developed in WA.
- These data sets need to be established and long-term sites identified to allow for ongoing assessment.
- Attributing costs is virtually impossible as there few, if any precedents for determining the cost of extinction of a species or the cost of replacing entire ecosystems.
- The impacts on significant groundwater resources within the Perth Basin and in other regions has not been assessed by this Audit.
- Future monitoring should consider assessing these groundwater resources and will require improved data sets
- A standard method for valuing water resources should be developed.
- There is limited groundwater information in some areas such as the Northern Perth Basin (Northern Agricultural region).
- Annual reporting is difficult due to the size of WA. Improved satellite interpretation, or extending the process used by WA in this Audit to a catchment level may provide a better estimates for future audits.
- Improved groundwater monitoring systems in agricultural areas will be critical for establishing better estimates of local and regional groundwater trends, depths and qualities. This would improve the estimates of areas at risk, and improve the estimates of management impacts leading to, and changes or delays in the eventual extent of salinity.
Monitoring of a range of data is critical to enable ongoing investigations. Future investigations should include:
- Identification of groundwater processes and trends in areas currently lacking data.
- Risk assessment at a larger scale more applicable to land management.
- Assessment of risk to water resources.
- Assessment of the impacts of changing land use management.
A state salinity council has been established in Western Australia to monitor implementation of the state's Salinity Action Plan. Responsibility for salinity in Western Australia lies primarily with Agriculture Western Australia (Ag WA), and the Water and Rivers Commission (WRC). Conservation and Land Management (CALM) also plays an important role.
Mapping of land salinisation
The Land Monitor Project is producing maps of the extent and recent (~10 year) change in areas of salt-affected/persistent low productivity land based on Landsat satellite data. Spatial resolution is 25 m by 25 m. The project covers the entire SW agricultural area (24 million hectares). Accuracy assessments of salinity mapping are carried out and published for sample areas within each region. Final products for one-third of the region are complete, with the balance due by March 2001.
For the NLWRA Salinity Theme, Short and McConnell (2000) mapped the current extent of shallow groundwater for the entire state at scales of 1:50 000 and greater, by attributing observed groundwater levels to landscape units. They also provided maps produced by the Natural Resource Assessment Group (NRAG) of Ag WA, of the proportion of wet and waterlogged soils by soil landscape. It was assumed that waterlogged soils or shallow groundwater tables corresponded to areas of current salinity extent or risk.
Both the WRC and Ag WA carry out groundwater monitoring programs. The WRC is primarily concerned with monitoring potable/industrial groundwater resources (Short and McConnell, 2000). The WRC's State Water Resources Information System (SWRIS) database contains periodic groundwater level and quality data for 3200 state bores, and periodic groundwater level data for 13 000 private bores.
Agriculture WA maintains groundwater datasets in agricultural areas that are used primarily for salinity research. Ag WA has over 5000 monitoring and research bores in its records. The Catchment Hydrology Group of Ag WA has been progressively entering these to its database 'AgBores'.
The NLWRA salinity project identified 4780 bores in AgBores that were suitable for future salinity monitoring. Ag WA has begun a census of bores currently monitored to determine those that should remain as priorities for long-term monitoring. An initial analysis has identified over 1400 bores that should receive priority to provide long-term groundwater trend data (Short and McConnell, 2000).
The spatial distribution of monitoring bores in the AgBores database in Western Australia is summarised in Table C.8. Figure C.6 shows the spread of bores with respect to local (light grey), intermediate (mid grey) and regional (dark grey) groundwater flow systems.
Table C-8: Distribution of Groundwater Monitoring Bores in Groundwater Flow Systems in Western Australia
|Basin Number||Basin Name||Region Name||kmē per monitoring Bore - Local GFS||kmē per monitoring Bore - Intermediate GFS||kmē per monitoring Bore - Regional GFS||kmē per monitoring Bore - Entire Basin|
|618||YARRA YARRA LAKES||AVON||2||364||-||47|
|614||MURRAY RIVER (WA)||PERTH-MANDURAH||-||-||6||29|
|1204||SALT LAKE||SALT LAKE||51||386||1575||1143|
Figure C-6: West Australian Monitoring Bore Network
Surface water monitoring
Surface water data are collected by the WRC and stored in the SWRIS database. The database contains continuous water level data for 360 stream and lake sites and continuous stream salinity data for 65 sites. Periodic water quality samples are available for 500 sites.
Mapping of land cover/land use
The Land Monitor Project is monitoring changes in extent and condition of perennial vegetation across the region. All clearing of native remnant vegetation must be subject to a formal environmental review. Ag WA has mapped land use for the entire state at scales ranging from 1:25 000 to 1:250 000. This mapping was funded partially by the NLWRA.
Modeling of current impacts
Damage to infrastructure is being monitored via the Rural Towns Program. Six towns have been selected for detailed analysis of hydrogeological characteristics, modeling of groundwater pumping strategies and development of an economic analysis model to quantify the infrastructure costs associated with the predicted rises in groundwater levels.
As part of the National Land and Water Audit, costs of salinity have been estimated for parts of the Great Southern and South Coast Regions (SS2020; NLRWA Implementation project). These will be linked to costs and benefits of available management options to provide better basis for policy decisions. Also as part of the Audit, a broad economic analysis was carried out after intersecting areas of shallow groundwater and salinity risk with infrastructure, water resources, agriculture and key areas for biodiversity conservation (Short and McConnell, 2000)
CALM have also been undertaking a biological survey of agricultural areas as part of the State Salinity Strategy. The agricultural zones cover all, or significant parts of, six of the eight biogeographic zones recognised in temperate south western Australia (CALM, 1999).
Ag WA has predicted the change in dryland salinity extent based on scenario analysis using the MODFLOW and FLOWTUBE models in specific cases and MAGIC in the Water Resources Recovery Catchments. Currently the focus is on determining the endpoint rather than short-term trends. The groundwater database has been used as the main source of temporal data (hydrographs), with various levels of confidence.
Ag WA and CSIRO have developed hydrograph analysis systems as a part of the NLWRA Implementation Project to determine of the impact of rainfall and related factors (Shao et al., 2000; Ferdowsian et al., 2000). This trend analysis model HARTT (Ferdowsian et al., 2000) is a major advancement in the analysis of hydrographs for salinity impact assessment and analysis.
The Land Monitor project is also developing methodologies to estimate salinity risk, defined as areas where there is a high probability of a shallow watertable developing at equilibrium. One model applies a water accumulation model derived from a high resolution digital elevation model (z < 2m x x, y, = 10 m) to a catchment. An attempt is then made to identify areas that may become saline because of their position in the landscape and proximity to salt-affected areas. The parallel method uses a decision tree (expert driven), digital elevation model and related variables.
For the NLWRA Salinity Impacts and Extents project, Short and McConnell (2000) produced maps of salinity risk for 2020 and 2050 by attributing observed groundwater trends to landscape units.
If we are to make informed decisions about how to prioritise our investment in salinity, and how to assess the effectiveness of investments, we need to be equipped with sufficient, good quality data that enable us to answer some fundamental questions at the catchment scale.
- How effective have management activities been?
- What is the likely future extent/severity/impact of salinity?
- What is the contribution to improving groundwater level of any salinity management investment?
- What investments are likely to deliver the most effective changes to water balance and over what time frame?
- How are systems-such as in-stream water quality, wetlands and soils-responding to improvements in groundwater level?
- What are the minimum components for an effective Australia-wide dryland salinity assessment and monitoring program?
- an analytical framework based on our understanding of hydrogeological processes controlling salinity, including timescales and spatial extents;
- evaluation methods and appropriate data (including indirect and surrogate indicators) that allow continuing evaluation of land management responses; the methods must enable the linking of biophysical, social and economic dimensions;
- consistent design and standards for data collection; and
- a capability to collect and manage data, and to produce information and assessments from this data.
Link to national overview of: What type of monitoring is needed for Australia?
- Dryland Salinity Evaluation and Monitoring Report
- Western Australia Dryland Salinity Assessment 2000 report
- Australian Dryland Salinity Assessment 2000 report
- National Technical Overview Report of the State-based dryland salinity assessments
- Australian Groundwater Flow Systems Report
- Agriculture WA
- National Dryland Salinity Program
- National Action Plan for Salinity and Water Quality
Link to the Map Maker to make a map using this information.
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