22/7/01
Is the Current Salinity strategy up the creek?
As a concerned Landholder wanting the best for the environment, Iam concerned that
Government departments are misleading the farming community about
the current discharge - recharge model of unconfined water aquifers in
Australia.
Several members of the scientific community including Dr Christine Jones
(NSW DLWC) have published papers challenging the way that water enters the
water tables and the over emphasis on trees to keep water table levels in
check.
There is now an alternative model which emphasises dense deep rooted
perennial grasses as the most important element in holding water where it falls and therefore
minimising salinity risk.
Our Australian Governments are rushing out to plant trees to prevent
salinity and in most cases it will be wasting taxpayers money in the
process.
Encouraging greater perennial grass cover would be a far less costly
and more beneficial salinity prevention strategy overall.
Another weakness with current practices is when trees do use more water in
shallow water tables, then they can draw more water into the area under the
trees and thereby concentrate the salt in that place. This is a self
defeating exercise.
What is a better idea is to reduce the water entering the water aquifer in
the first place.
Below is a summary of the issue.
The assumed model
Deep rooted trees USE large amounts of water and keep water table in balance.
Tree removal results in water table recharge in upper catchment and
discharge in lower catchment.
Prior to Settlement
Today
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B: a more realistic model
Healthy perennial groundcover, fibrous root mass and associated humic
materials HOLD water where it falls with some percolation to groundwater.
Loss of healthy groundcover in both upper and lower catchments results in
more runoff, lateral flow, recharge and discharge. Replenishment of elevated
aquifers may be reduced.
Prior to Settlement Today
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Contact Leon Ashby 0887 389313
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