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Salinity - Monitoring - Victoria

Victoria

Monitoring now and in the future

Groundwater and salinity monitoring

Monitoring was and remains a key component of the Victorian Salinity Program. Since its inception in the 1980?s there have been significant resources devoted to establishment and maintenance of groundwater and surface water monitoring, mapping and monitoring of saline discharge areas and to monitoring remnant vegetation and wetlands threatened by dryland salinity. This investment in monitoring activities means that the state has a relatively comprehensive monitoring network, long-term records and effective monitoring and data management arrangements.

There are two main observation bore networks in Victoria that provide groundwater monitoring information:

• State Groundwater Observation Bore (SGOB) network - a network of observation bores constructed for salinity and groundwater resource monitoring purposes;
• Victorian Salinity monitoring network - a less formal network of observation bores established for community education, groundwater process investigation and salinity monitoring.

Groundwater data are maintained in two databases operated on behalf of NRE. There is regular interchange of data between the two and progress towards web-based delivery of groundwater information.

Several shortcomings in the groundwater monitoring network and databases have been identified that detract from their value in a salinity audit such as this, including:

• concentration of bores in areas of shallow water tables
• under-representation of ridge and upper slope areas
• lack of accurate elevation information for a significant number of bores
• errors in water level records
• poor representation of parts of the state outside those traditionally considered to be at risk of salinity.

A single surface water quality monitoring network operates across Victoria, the Victorian Water Quality Monitoring Network (WQMN). Approximately 280 stream and lake gauging stations are maintained throughout Victoria. Stations within the network have operated for up to 25 years, with water quality measurements taken at least at monthly intervals. Long-term continuous flow and salinity measurements are available for many stations within this network.

Requirements for future salinity assessments

This study and the companion work in support of the Murray-Darling Basin Salinity Audit have provided a useful first estimate of the regional extent and potential impact of shallow water tables and dryland salinity. Groundwater and salinity related data from across the state have been brought into a single interpretation framework in ways not previously attempted. However, the results of this assessment are by no means the last word on salinity risk and future impact in Victoria.

It is not considered appropriate for any future salinity assessment to repeat the work reported here. Rather it should seek to obtain, at a regional level, a more precise indication of the water table surface, the way in which it would be expected to change over time and of the true impacts of this. The following list outlines some key steps that would be required in advance of and during such an assessment:

• addressing shortcomings in monitoring networks
• use of finer resolution digital elevation models
• better incorporation of an understanding of groundwater behaviour and catchment water balance
• better understanding of the impacts of shallow water tables on environmental and infrastructure assets
• determination of water quality impacts for streams across the entire state

The resources required to support such work at a regional level would not be trivial. Priority actions would be to redress the shortcomings in the representativeness of the monitoring network. This would best be done in the context of a series of regional strategic reviews of groundwater and salinity monitoring.

Recommendations

• Support for groundwater and salinity monitoring be maintained as a key component of the Victorian Salinity Program;
• Reviews of groundwater and salinity monitoring networks and arrangements be undertaken in each Catchment Management Authority region with a view to ensuring an appropriately resourced, efficient and representative monitoring network;
• Key shortcomings in the Victorian groundwater monitoring network, particularly the lack of surveyed elevation for many bores and the under representation of more elevated locations, be redressed;
• Any future audit of the potential extent and impact of salinity be conducted at a more detailed regional level and incorporate finer resolution digital elevation models and a higher level of understanding of groundwater and catchment water balance processes than was possible here.

Such work is under way the Goulburn region. Priority for other similar studies are the areas where future salinity risk and/or potential impact is high, including the Loddon and Avoca catchments of northern Victoria and the Glenelg and Corangamite regions of south-west Victoria.

What is being monitored

Victoria

Responsibility

The Department of Natural Resources and Environment (DNRE) has primary responsibility for salinity management in Victoria. Within DNRE, the Centre for Land Protection and Research contains salinity expertise. Some monitoring activities have been contracted out to the consulting firm Sinclair Knight Merz.

Mapping of land salinisation

DNRE undertook a 10 year assessment of dryland salinity at 1:25 000 scale which was completed in 1994. The assessment covered most of the state with the exception of the Mallee region, areas of West Gippsland east of the Gippsland Lakes and some areas of the Port Phillip region. The study was based on visual symptoms such as reduced groundcover and changes in botanical composition of pastures (Allan, 1994 and 1996).

Since this study, 46 monitoring stations have been established. These are not systematically coordinated by the state government, but are supported by community groups. The sites are generally visited once every four years. On each visit, salinity is mapped using ground based electromagnetics and field observation of indicator plant species, impact to agricultural plants, observation of scalding or other surface indicators, and soil salinity measurements.

For the NLWRA Dryland Salinity theme, Sinclair Knight Merz estimated the extent of shallow watertables for hydrogeomorphic units based on water level data from groundwater monitoring sites. They derived relationships between ground surface elevation and water table elevation, existing salinity mapping and GIS layers showing location of streams, lakes and wetlands, urban areas, irrigation districts and forests and woodlands (Clifton, 2000).

Groundwater monitoring

Victoria has a substantial network of groundwater observation bores. These bores were constructed for water resource investigations and dryland salinity investigation and monitoring. Most salinity monitoring bores were constructed after the launch of the Victorian Salinity Program in the late 1980s. There are two main observation bore networks:

• State Groundwater Observation Bore (SGOB) network;
• Victorian salinity monitoring network - a less formal network of observation bores established for community education, groundwater process investigation and salinity monitoring.
• Shortcomings in the groundwater monitoring network and databases that detract from their value in analysis of dryland salinity include (Clifton, 2000):
• concentration of bores in areas of shallow water tables;
• under-representation of ridge and upper slope areas;
• lack of accurate elevation information for many bores;
• errors in water level records;
• poor representation of parts of the state outside those traditionally considered to be at risk of salinity.

The spatial distribution of monitoring bores in Victoria is summarised in Table C.3 and shown in Figure C.3 below. The figure shows the spread of bores with respect to local (light grey), intermediate (mid grey) and regional (dark grey) groundwater flow systems.

Table C-3: Distribution of Groundwater Monitoring Bores in Groundwater Flow Systems in Victoria

Basin Number	Basin Name	Region Name	km² per monitoring Bore - Local GFS	km² per monitoring Bore - Intermediate GFS	km² per monitoring Bore - Regional GFS	km² per monitoring Bore - Entire Basin
408	AVOCA RIVER	WIMMERA-MALLEE	172	2	0	15
415	WIMMERA-AVON RIVERS	WIMMERA-MALLEE	30	10	0	8
407	LODDON RIVER	GOULBURN-LODDON	0	0	10	4
404	BROKEN RIVER	GOULBURN-LODDON	16	5	-	5
239	MILLICENT COAST	MILLICENT COAST	-	-	1	20
403	OVENS RIVER	UPPER MURRAY	13	7	-	9
405	GOULBURN RIVER	GOULBURN-LODDON	12	4	-	9
406	CAMPASPE RIVER	GOULBURN-LODDON	4	3	4	4
224	MITCHELL RIVER (VIC)	GIPPSLAND	-	225	4	11
238	GLENELG RIVER	HAMILTON	0	1	24	5
236	HOPKINS RIVER	HAMILTON	1	1	9	5
225	THOMSON RIVER	GIPPSLAND	-	16	2	4
230	MARIBYRNONG RIVER	MELBOURNE	0	1	139	5
229	YARRA RIVER	MELBOURNE	6	11	-	11
231	WERRIBEE RIVER	MELBOURNE	-	-	3	4
232	MOORABOOL RIVER	OTWAY	4	1	12	7
233	BARWON RIVER	OTWAY	0	1	7	2
234	LAKE CORANGAMITE	OTWAY	1	2	3	2
226	LATROBE RIVER	GIPPSLAND	82	4	6	7
228	BUNYIP RIVER	MELBOURNE	-	3	-	4
237	PORTLAND COAST	HAMILTON	-	126	42	58
227	SOUTH GIPPSLAND	GIPPSLAND	25	1	75	15
235	OTWAY COAST	OTWAY	2	1	0	2
228	BUNYIP RIVER	MELBOURNE	-	-	0	2
414	MALLEE	WIMMERA-MALLEE	-	-	33	47

Figure C-3: Victorian Monitoring Bore Network

Surface water monitoring

A single surface water quality monitoring network operates across Victoria. The Water Quality Monitoring Network (WQMN) consists of 280 stream gauging stations that have operated for up to 25 years, with water quality measurements taken at least at monthly intervals. Long-term continuous flow and salinity measurements are available for many stations.

Mapping of land cover/land use

DNRE's Catchment Health Indicator Program aims to provide an indicator-based assessment of 'health' for Victorian Catchment Management Authorities. Several proposed indicators are related to land use/cover including remnant vegetation condition and land use and management compared spatially to land capability. The project is based upon a combination of existing data and data collected specifically for the catchment health assessment. While the project is funded for only four years, the project aims to set up an assessment framework which could provide ongoing monitoring of catchment attributes.

DNRE has also mapped land use in the Gippsland region as part of a NLWRA implementation project. Land use mapping is underway in 2001 in the Goulburn-Broken catchment as part of the MDBC Landmark project. It is anticipated that MDBC will fund mapping of the remainder of the Murray-Darling Basin component of Victoria, and that the rest of the state will be mapped as part of the Bureau of Rural Sciences' national land use mapping program. Mapping scales range from 1:25 000 for intensive land use areas to 1:100 000 in more remote regions.

Modeling of current impacts

The Catchment Health Program incorporates several indicators relevant to salinity impacts including biodiversity, index of stream condition, and gross value of production.

The NLWRA salinity report for Victoria summarised key assets at risk from salinity by intersecting the salinity current extent and future predictions maps with land use (Clifton, 2000).

Future Extent

Little modeling of future salinity extent was undertaken in Victoria prior to the NLWRA Extent and Impacts of Dryland Salinity project. For the NLWRA project, Sinclair Knight Merz superimposed observed groundwater trends on hydrogeomorphic units to estimate areas affected by waterlogging and salinity in 2020 and 2050 (Clifton, 2000).

What type of monitoring is needed for Australia?

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?

We need:

• 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?

Further information

• Dryland Salinity Evaluation and Monitoring Report
• Victoria 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
• National Dryland Salinity Program
• National Action Plan for Salinity and Water Quality

Victorian v- Spreadsheet Data Files
Victorian Dryland Salinity Assessment 2000 - Salinity Risk Classification Under Best Case Trend Scenario
Victorian Dryland Salinity Assessment 2000 - Salinity Risk Classification Under Worst Case Trend Scenario
Victorian Dryland Salinity Assessment 2000 - Predicted Depth To Water Table Surface in 2050 under Best Case Trend Scenario
Victorian Dryland Salinity Assessment 2000 - Predicted Depth To Water Table Surface in 2020 under Best Case Trend Scenario
Victorian Dryland Salinity Assessment 2000 - Predicted Depth To Water Table Surface in 2050 under Worst Case Trend Scenario
Victorian Dryland Salinity Assessment 2000 - Predicted Depth To Water Table Surface in 2020 under Worst Case Trend Scenario
Victorian Dryland Salinity Assessment 2000 - Current Depth to Water Table
Victorian Dryland Salinity Assessment 2000 - Best Case Trends
Victorian Dryland Salinity Assessment 2000 - Worst Case Trends
Victorian Dryland Salinity Assessment 2000 - Point Coverage of Bore Locations - Northern Victoria
Victorian Dryland Salinity Assessment 2000 - Point Coverage of Bore Locations - Southern Victoria

Link to the Map Maker to make a map using this information.

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