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INTRODUCTION This presentaDon shows the effecDveness of VeDver
System Technology (VST) as a tool of bioengineering as compared with other commonly used methods to control erosion on steep slopes.
The site was on a highly erodible fill materials consisted of weathered sandstone and sandy soil. It is on a very steep gradient, averaging 45 degrees and up to 50 degrees at some secDons.
The original baVer was built from material excavated and pushed down slope for a home site on a very steep mountain range
The climate is subtropical, with cool and occasional frost in winter, and wet summer with prolonged period of high intensity rainfall and occasional cyclonic downpour
This presentaDon shows the result two years aXer implementaDon aXer numerous storms and recently a 350mm rainfall over a 5 day period.
This is a very complex site, with very steep gradient in two direcDons, with slope gradient up to 500 in some
parts
100m long, up to 500
400m long, up to 450
Original baVer from material
excavated and pushed down slope for a home site
House
House
100m long, up to 500
Original baVer from material
excavated and pushed down
slope
House
Front of the house
House
100m long, up to 500
Hydroseeding with turf grass to control erosion and stabilise the
baVer
Rilling started soon aXer
Hydroseeding
Rilling started soon aXer
Hydroseeding
House
100m long, up to 500
Rilling was so severe that a geofabrics was
used to cover the whole baVer to prevent further
erosion
House
A very elaborate and expensive operaDon, including sand bags to weight down the geofabrics cover
Lomandra, a shallow rooted ornamental
species was planted to stabilise the baVer
Despite this costly measure the baVer collapsed during an average summer rainfall and it was rebuilt with imported fill materials
The baVer was rebuilt with imported fill
Concrete blocks was built as retaining wall at the foot of the baVer
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Laying Geo\rics: Jutemesh
VeDver planDng
VeDver planDng
Six months aXer planDng
8 months aXer planDng
10 months aXer planDng
Two years aXer planDng, aXer
slashing
Two years aXer planDng, before slashing
Two years aXer planDng, aXer
slashing
Two years aXer planDng, prolific growth, 2.5m high with roots to at least 2m
deep
PracDcally no sediment in
downslope drain
CONCLUSION
This presentaDon shows the superiority of VST as compared with other commonly used methods to control erosion on steep slopes, both in term of effecDveness and cost.
VST has passed the ulDmate test two years aXer implementaDon with a recent rainfall period of over 350mm in 5 days.
In addiDon to its steep slope stabilisaDon efficiency, it also completely prevented sediment moving down the slope