Maps produced for NSW show known areas of dryland salinity and shallow water tables. An improved spatial coverage of current saline outbreak areas and more extensive bore network is required to fill gaps in the spatial extent of the data.
Acquisition and compilation of data from a larger number of monitored bores is required to improve estimates of rates of groundwater rise. More detailed groundwater flow systems data need to be used to refine the estimated rates of rise.
A major outcome from the NSW study was that existing techniques that relate topography to depth of water table were inadequate. Mre complex topographical attributes need to be assessed as an indicator of shallow water tables to improve current and future extent maps.
Revised current and future extent maps could be used to refine the end of valley salt loads for Murray-Darling Basin Catchments as part of the MDBC Salinity Audit updates.
Results showed the large extent of dryland salinity in the Hunter Catchment. Further work is required to improve current and future predictions of dryland salinity in the Hunter.
A more comprehensive salinity assessment is required through the integration of these results with spatial models of water and salt movement in the landscape and socioeconomic data to provide tools for regional and catchment planning
Each of these activities are being addressed under the NSW State Salinity Strategy.
New South Wales
The Department of Land and Water Conservation (DLWC) has the primary responsibility for dryland salinity management and research in New South Wales. The Department of Agriculture and the Environmental Protection Agency are also prominent in salinity management.
Mapping of land salinisation
Mapping of dryland salinity in New South Wales has been based on a system developed in 1981-1983, with some modifications where unique patterns were encountered. Scald areas, salt-tolerant species and surface soil salinity in gullies were mapped based on aerial photography and field checking, landholder surveys, satellite imagery and the knowledge of departmental officers. Not all of New South Wales is covered by this mapping system. While information is good for much of the Murray Darling Basin and for a number of coastal catchments including parts of Shoalhaven, Wollondilly, Hunter, Richmond Tweed and Sydney Western region, very little information is available for western New South Wales.
For the NLWRA Dryland Salinity Theme, DLWC combined salinity mapping according to the above method with areas where groundwater tables less than 2m below surface had been measured. This substantially underestimates salinity in the state as it has been mapped only where there is either airphoto interpretation or bore data (Littleboy et al., 2001).
DLWC maintains a groundwater database consisting of two types of bores. The first, production bores, consist of only one measurement of groundwater level, taken at the time of drilling. Production bore data contain many errors, especially in determination of the depth of the water table. These data are collected by the driller and forwarded to DLWC. Often drillers neglect to complete the required data collection in sufficient detail and the reported water levels in bores may also not reflect equilibrium conditions after drilling. There are 7036 production bores with data from the period between 1980 and 2000. Littleboy et al. (2001) applied quality control procedures to reduce this number to 5943 suitable bores for salinity evaluation purposes.
The second type of bores in the database is monitored bores, that is bores which have time series data. While information for many monitoring bores is stored in the central database, an additional substantial amount of information is also maintained within regional datasets. A series of reconnaissance surveys was undertaken in the early 1990s to measure water level and salinity in these bores. In many cases there are only two measurements per bore, one from the time of drilling and another from the reconnaissance survey. Bores with more than two measurements are limited mainly to the Central West Region (Macquarie and Lachlan). In their NLWRA report, Littleboy et al. (2001) used 986 suitable two point bores, and 287 three point bores.
The spatial distribution of monitoring bores only (not production bores) in New South Wales is summarised in Table C.2. Figure C.2 shows the spread of bores with respect to local (light grey), intermediate (mid grey) and regional (dark grey) groundwater flow systems.
Table C-2: Distribution of Groundwater Monitoring Bores in Groundwater Flow Systems in New South Wales
|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|
|206||MACLEAY RIVER||COFFS HARBOUR||24||28||913||153|
|401||UPPER MURRAY RIVER||UPPER MURRAY||24||25||-||25|
|416||BORDER RIVERS||BORDER RIVERS||2||5||151||48|
|425||DARLING RIVER||MENINDEE LAKES||-||30||4512||220|
|204||CLARENCE RIVER||COFFS HARBOUR||74||93||543||259|
Figure C-2: New South Wales Monitoring Bore Network
Surface water monitoring
Most of the New South Wales historical stream data are held in the DLWC HYDSYS database and the DLWC TRITON water quality database. Further records are available at regional DLWC offices. While time series data for streamflow are quite extensive, stream salinity data are patchy. For example, for the outflows of major catchments across the state, there are on average 20.5 years of continuous observed flow data and only 152 corresponding discrete EC measurements (Beale et al., 2000).
For current and recent stream information, the Provisional River Data System provides information on water level, water temperature and water salinity from 350 locations using data gathered from monitoring sites by radio and telephone systems. These data are retained on DLWC's website for three months before being archived.
Mapping of land cover/land use
DLWC has mapped land use at a scale of 1:25 000 in some small initial areas such as Young as part of the Murray-Darling Basin Commission Landmark study. The Bureau of Rural Sciences has contracted DLWC to map a large proportion of the state as part of a national land use mapping program.
Modeling of current impacts
The NLWRA salinity report for New South Wales summarised key assets at risk from salinity by intersecting the salinity current extent and future predictions maps with land use (Littleboy et al., 2001).
Assessments of the likely trend in dryland salinity occurrence have been undertaken by DLWC for two catchment plans:
- Kyeamba Valley Study (1991-1992). Information from four bores was used to predict the areas likely to be affected by future outbreaks of dryland salinity. The bore data were matched against slope/terrain mapping. All areas of colluvial soils (footslopes, drainage depressions) where the groundwater pressure was positive were deemed to be at risk. Alluvial areas were considered not at risk because the aquifer systems were still draining.
- Wantiool Catchment Plan (1993): The Wantiool Study adopted the same approach but without the benefit of bore data.
For the Dryland Salinity theme of the NLWRA, New South Wales produced maps of predicted 2020 and 2050 salinity based on a synthesis of current groundwater depth, measured rates of groundwater rise and identification of salt outbreaks from airphoto interpretation.
Work with the terrain analysis model FLAG, Fuzzy Landscape Analysis GIS, (Roberts et al., 1997) is currently being undertaken. FLAG provides several indices of landscape position based on a high resolution digital elevation model. These indices can be used to predict likely areas for surface expression of salinity and waterlogging. FLAG is also being combined with hydrogeological information to identify areas of accumulation and divergence and predict the subsurface flow of saline water.
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
- New South Wales 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
- New South Wales Department of Land and Water Conservation
- 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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