You are here: ANRA home » Natural resource topics » Dryland Salinity » Management » New South Wales
This web site is no longer being updated
In this section you will find detailed information, including national overviews and state and regional level assessments, from the 2000-2002 National Land and Water Resources Audit theme assessments.
Salinity - Management - New South Wales
New South Wales
Introduction
Water balance
As the groundwater system fills and eventually reaches a new equilibrium, the amount of water entering the landscape as recharge and the amount of water leaving as discharge is balanced. However there is a time lag between when changes in land use or improvement in water balance occurs and evidence of a response. It will take decades to reverse the water rise in most groundwater systems (see figure below).
Re-establishing the water balance requires farming systems with similar water use to that of deep-rooted native vegetation. Designing and implementing such farming systems is a major challenge.
Recharge processes are generally faster than discharge processes. If it takes 30 to 50 years for our fastest groundwater system to fill with water, then it is reasonable to expect that it might take at least 30 to 50 years for it to empty back to where it was. If the system takes 100 years or more to fill, we can again expect at least a similar amount of time to establish the original equilibrium. This is an important issue for management as the degree of recharge reduction and the time taken have important consequences on land use options during any adjustment period, and the degree of change sought. Beneficial effects of land use options may well occur before the system has returned to an equilibrium.
Salt balance
As more water moves through an aquifer, more salt is mobilised. Very long periods of time are needed for catchment salt stores to be reduced to the point where the amount entering the system equals the amount leaving the system, that is, to achieve a salt balance. The net amount of salt that exits a catchment via stream flow indicates the time it will take for the catchment to flush its store of salt, when compared with the total mass of salt stored in that catchment. In some of the more responsive groundwater flow systems, the net output of salt may take about 150 years to flush from the system. In larger catchments (e.g. the Murray groundwater basin), it may take as much as 15 000 years. This means that although management may lower the watertable and allow productive use of land, there may be ongoing salt inflow to streams via groundwater.
This makes managing stream salinity very difficult. It is very important to prevent the interception of groundwater with salt stores in regions where we still have this opportunity.
The reality
The substantial lag times for catchments to come back into water balance and change salt mobilisation mean that it is inevitable that dryland salinity will be a feature of many Australian landscapes for some time. This is true even with widespread adoption of innovative land uses that manage to turn off the recharge tap and re-establish water balance. Ultimately the decisions on the measures to be taken will be influenced by the value of the threatened assets, the capacity to manipulate the environmental processes, the economic feasibility and social acceptance of the proposed actions.
What is the scale of the groundwater systems and how can they be managed?
Groundwater trends
The forecasted areas of risk for 2020 and 2050 are based on water table rises calculated from a network of monitored groundwater bores in NSW. These are fully described in Appendix 1 and are summarised as catchment average water table rises in the table below.
Highest rates of rise are evident for the southernmost catchments in NSW. Rates of water table rise tend to decrease in a northerly direction. This suggests that the impacts of rising water tables will take longer to surface in the northernmost catchments of NSW. High rates of water table rise for the southern catchments is one factor explaining the larger extent of current shallow water tables and dryland salinity in southern NSW.
| Catchment | Rise (m/yr) |
|---|---|
| Murray | 0.15 |
| Murrumbidgee | 0.14 |
| Lachlan | 0.11 |
| Macquarie | 0.09 |
| Castlereagh | 0.11 |
| Namoi | 0.06 |
| Gwydir | 0.04 |
| Macintyre | -0.01 |
More detailed information is available in the New South Wales Dryland Assessment 2000 Report
The groundwater flow systems for New South Wales are present in the table below. Within the >300mm rainfall zone, 135,000 hectares in local, 1,064,000 hectares in intermediate and 138,000 hectares in regional flow systems are coincident with regions within which there are areas with a high risk of dryland salinity.
| Groundwater Flow System Type | Area (ha) at risk in 2050 | Percentage of total risk area(%) |
|---|---|---|
| Intermediate flow systems in sedimentary sequences in large valleys | 5,026 | 0 |
| Local flow systems in fractured or weathered rocks or colluvial fans | 134,662 | 10 |
| Intermediate flow systems in fractured rocks | 771,301 | 59 |
| Local flow systems in fine grained unconsolidated sediments | 123 | 0 |
| Regional flow systems in alluvial aquifers | 137,466 | 11 |
| Regional flow systems in marine sediments overlain with some local flow systems in sand dunes | 297 | 0 |
| Regional and intermediate flow systems in fractured basaltic rocks and layered sedimentary rocks | 102,517 | 8 |
| Intermediate and local flow systems in fractured basaltic rocks and layered sedimentary rocks | 152,929 | 12 |
* Area within >300mm rainfall zone
Government responses to dryland salinity as at the year 2000
Government responses
In response to dryland salinity issues, the New South Wales Government released its State Salinity Strategy in August 2000 (Department of Land and Water Conservation 2000) that provides a single integrated framework for salinity management in New South Wales. It advocates a shared responsibility involving land managers, conservationists, Aboriginal communities, scientists, businesses and all levels of Government to tackle the salinity problem. The key tools within the Strategy are to:
- Develop end of valley salinity targets that reflect the salinity levels we are prepared to live with and can afford.
- Establish market-based solutions and encourage strategic investment to provide land managers with an incentive to manage their properties for specific environmental outcomes, such as reduced salinity.
- Introduce a Salinity Business Development Program to encourage emerging industries that can use saline land productively.
- Better use of regulatory tools such as incorporating salinity impact assessment into the clearing application approval process, water licensing and environmental planning instruments.
- Improve the ability of frontline staff to provide salinity advice to land managers.
- Invest in upgrading data and analytical tools and in ensuring that information is user-friendly and easily accessible.
- Undertake and facilitate research into land use systems that minimise recharge; use of saline-affected land and water; impacts of salinity on natural ecosystems; and the social and economic issues.
- Improve the focus of catchment management planning systems through Catchment Management Boards to manage for change at the appropriate geographical scales.
Further information
- 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 Map maker to make a map using this information.
Before you download
Most publications are downloadable as PDF files. Adobe Acrobat Reader is required to view PDF files.
If you are unable to access a publication, please contact us to organise a suitable alternative format.
Key
Links to an another web site
Opens a pop-up window