People - Capacity to change - case studies of dryland salinity and watertable control - Australia
By Mike Read, Read Sturgess and Associates
Assisted by:
Alistair Watson - Freelance economist
Neil Sturgess - Read Sturgess and Associates
David Pannell - University of Western Australia
June 2001
The National Land and Water Resources Audit (NL&WRA) commissioned a project to identify the likely constraints to adoption of measures to control dryland salinity in Australia that concentrated on four catchments as case studies:
Wanilla catchment, a small basin of about 17,000 hectares, situated about 40 km to the north west of Port Lincoln on the lower Eyre Peninsular, South Australia. Salinity impacts within the Study Area appear mainly along strips of farmland which are contiguous with the natural drainage lines. At present 8 per cent of the catchment is salinised and CSIRO modelling suggests that, without management, this will increase to 17 per cent over the next 50 years.
Lake Warden catchment, situated near the coastal town of Esperance on the south east coast of Western Australia. Salinity impacts within the Study Area appear mainly on farm land and around important wetlands at Esperance, as well as other low lying waterbodies. At present 8 per cent of the catchment is salinised but this is expanding rapidly and CSIRO modelling suggests that, without management, the extent will increase to 45 per cent of the catchment over the next 50 years.
Kamarooka catchment, located in north-central Victoria on the northern slopes of the Great Divide. Salinity impacts within the Study Area appear mainly on farmland along the 'break-of-slope'. At present 7 per cent of the catchment is salinised and CSIRO modelling suggests that, even without further management, this has now stabilised.
Upper Billabong Creek catchment, located NW of Holbrook (NSW) in the Murray Darling basin. At present much less than one per cent of the catchment is salinised and CSIRO modelling suggests that, even without management, this will increase only to about one per cent over the next 50 years. The salt load exported from the Upper Billabong Creek catchment contributes only a very small part of the water quality problems at the bottom end of the Murray River.
This used the outputs of catchment water balance modelling undertaken by CSIRO Land and Water and formed projections about future extents of salinity.
Analysis included a comparison of benefits and costs associated with salinity control in each of the four case study catchments. The approach adopted was to take estimates of the physical scale of impacts for each type of damage caused by dryland salinity (e.g. area of agricultural enterprises, number of stream diverters, kilometres of roads affected, number of species affected), and to apply damage functions for each of those types of impact. Data describing the physical scale of impacts have been captured using mainly GIS layers which describe the location of dryland salinity in each case study catchment. The damage functions to quantify the economic impacts of dryland salinity are for:
- agriculture and commercial forestry;
- roads and rail;
- urban centres;
- water users; and
- environmental values.
The study of benefits and costs of dryland salinity has benefited greatly from other major economic research projects that have been undertaken concurrently, particularly those undertaken in Western Australia for the Grains R&D Corporation (GRDC), and those undertaken by the Australian Bureau of Agricultural and Resource Economics (ABARE) in the Murray Darling Basin. In each of those projects, the economic benefits and costs of various salinity management options have been compared for catchments.
In aggregate, those catchments represent a significant and representative sample of areas affected by dryland salinity across Australia, and all the studies have arrived at very similar conclusions:
- Most of the control of dryland salinity aimed at protecting agricultural values should focus on changes to farming systems at a farm scale.
- The role for catchment-scale tree planting is extremely limited.
- It will be not be economically sensible to control most dryland salinity and hence the community will have to 'live with' much of the existing (and looming) dryland salinity across Australia. This is because, for many catchments, the scope is presently limited by a lack of technically and/or financially acceptable alternatives, and each catchment needs to be considered on its own merits.
- Externalities for downstream water quality may not be as great as previously thought; notably, impacts for human consumers of salinised water (e.g. Adelaide and Perth) may not be as high since it may be much cheaper to treat the salinised water supplies rather than control all of the dryland salinity in a catchment. Similarly, many environmental impacts may be treated more cheaply with engineering approaches rather than control all of the dryland salinity in a catchment (e.g. Lake Warden wetlands). The community's valuation of external benefits from the viewpoint of unpriced environmental values remains unknown. Those environmental values could provide some substantial justification for government intervention.
- The availability of technical options is the greatest constraint to our capacity to change for dryland salinity at present. The other two constraints of particular importance are the limited availability of benefits and elements of risk, such as the effects of unexpected commodity price shocks. Other important but lesser constraints would be lack of information and political constraints.
- Most decisions about where to implement salinity control will be made by private landholders as Government has a relatively small role to play in the provision of private benefits to individual landholders.
- Further studies of individual catchments are required to identify relative priorities for future funding. It is premature to commit substantial levels of government funding until further studies of individual catchments have been undertaken.
Detailed case studies of individual catchments, including substantial fieldwork, has proven an effective and efficient approach for gaining an understanding of the economic consequences of dryland salinity across Australia. Only four case studies were undertaken for this Study, but even so a considerable amount of useful information was obtained. The modelling framework developed for this Study is extremely portable and can be applied readily to other catchments. It is recommended that further case studies be evaluated using the same analytic framework as developed for this Study.
View or download the technical report and appendices:
- Capacity to change - Case studies of dryland salinity and watertable control by Mike Read. (PDF - 1.2 MB)
- Capacity to change - Case studies of dryland salinity and watertable control - APPENDICES by Mike Read. (PDF - 1.9 MB)
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