Native
vegetation clearance has wide-ranging effects on water quality,
habitats and biodiversity. Clearing the landscape of trees and
shrubs changes the direction and rate of rain runoff, and increases
erosion. This means more sediment, nutrients, salt, pesticides
and other toxicants are transported into rivers and streams.
Towns and cities increase the volume of stormwater due to their
large area of impervious surfaces (roads, roofs, footpaths, carparks)
compared with well-vegetated catchments.
The
National Land and Water Resources Audit (2001) recently found
that, of the river length assessed in South Australia, 95% had
water with elevated loads of suspended solids, total phosphorus
and total nitrogen.
