Dealing with salinity in Wheatbelt Valleys - Department of Water

Pannell
been conducted for the Central, Eastern or
Northern Wheatbelt.
Table 2 shows the infrastructure assets “at risk” in
Western Australia by 2020 as estimated by the
National Land and Water Resources Audit (2001)
Table 2: Physical infrastructure at risk from dryland salinity in Western Australia by 2020, based on
predicted groundwater trends and “best guess” future land use.
Asset Quantity at risk by 2020
Highways (km) 840
Primary roads (km) 745
Secondary roads (km) 1,425
Minor roads (km) 13,650
Rail (km) 1,490
In the National Land and Water Resources Audit
(2001) report, costs of these and other impacts
were reported for WA in a way which made
interpretation difficult. Nevertheless, the results
indicated that costs due to road damage will be the
biggest single cost due to salinity in this state.
Flood risk
Increased flood risks have been studied for only a
small number of case studies (Bowman & Ruprecht
2000). Extrapolating from these, George et al.
(1999) concluded that, with the predicted two- to
four-fold increase in area of wheatbelt land with
shallow watertables, there will be at least a twofold
increase in flood flows.
There has been no economic analysis of this
additional flood risk or its management. One
question is whether the costs of floods will be
sufficient to justify major revegetation of
catchments. Based on a consideration of the large
areas over which flood waters can be collected in
wheatbelt catchments, and the occasional nature
of floods, my hypothesis would be that flood risk
will provide only small to modest additional
incentives for establishment of perennials. It may
be more efficient to construct engineering works
near to flood prone assets. Further economic
studies to examine these issues would be useful.
– 8 –
Intangibles
Environment
According to George et al. (1999), in Western
Australia, without massive intervention, most or all
of the wetland, dampland and woodland
communities in the lower halves of catchments will
be lost to salinity. There are at least 450 plant
species and an unknown number of invertebrates
which occur only in these environments and are at
high risk of extinction (State Salinity Council 2000;
Keighery 2000). National estimates by the
National Land and Water Resources Audit (2001)
are that by 2050, there will be a high salinity
hazard for 2,000,000 ha of remnant and planted
perennial vegetation, 41,000 km of streams or lake
perimeter, and 130 important wetlands.
Economists have taken an increasing interest in
environmental impacts such as these. One body of
work attempts to place dollar values on intangible
impacts such as these (Van Bueren & Bennett
2001). My view is that this is fraught with the
greatest difficulties, and probably makes only
modest contributions to the decisions we need to
make about these assets. Nevertheless
economists can make an important contribution to
these decisions by quantifying accurately the direct
and indirect costs to the public and private sectors
involved in protection of environmental assets.