Page 6 - Landscape-Issue127

PROJECT

OLIFANTS RIVER

SIDE ARM REHABILITATION

Chris Devine of Blue Wood Landscaping received the 2023 SALI Shield of Excellence
in Landscaping for this project, and supplied Landscape SA with the information

below, which has been edited due to its length. He also received awards for the
Best Environmental Landscape and Best Water Wise Entry.

he section of the Olifants River affected is situated
in Citrusdal, Western Cape, and the project area falls
Twithin the Olifants River Valley. The river runs in a
south to north direction through the valley.
The braided channel of the Olifants River was found
to be in a largely to critically modified state, attributed
to the negative impact of clearing activities on loss
of biodiversity and flow modification; this resulted in
erosion, possible flooding and sedimentation further
downstream.
Flooding of the orchards located within the floodplain
occurs every year during the rainy season, leading to a
significant loss of trees and produce. In order to prevent
this, the channel was cleared to create a higher top of
bank, attempting to form a barrier prohibiting water from
entering the orchards. Due to the sandy nature of the
channel, these barriers have only been partly successful,
being breeched at places and leading to the flooding of
orchards regardless.
Although rehabilitation of the channel was the highest
priority, it needed to be done in a sustainable manner,
both ecologically as well as for the agricultural activities
that needed to commence. A river management plan
Nursery maintenance in July 2022

was compiled and adopted for the Upper Olifants River in order to
provide sustainable maintenance activities, whilst improving the
health and functioning of the Olifants River in 2020.
Recommendations were therefore to rehabilitate the channel
according to the rehabilitation plan so that flow would be directed
past the orchards. High planted banks along the north of the
channel, together with instream vegetated areas, would still act as
refuge habitat and flood attenuation areas, whilst re-introducing
the natural morphology of the river, including pools and ridges.
This would ensure that the orchards located in the middle of the
floodplain area were protected, with some flow allowed to pass
unimpeded through the channel, whilst being slowed down by
planted instream areas. It would also reduce the risk of erosion on
the channel banks and beds, and limit downstream sedimentation
and flooding.
Rehabilitation objectives and solutions
Other than general alien invasive plant removal from the braided
channel, the rehabilitation plan was relevant to:
• the new higher stream bank located along the northern section
of the channel;
• the instream zones including ridges and pools; and
• the larger, intermittently wet floodplain area.

The rehabilitated section was landscaped only where necessary,
to match the topography of the surrounding area as it was prior
to construction. All landscaping was done by hand, and there
was no use of large construction vehicles and machinery. A strict
South westerly view of the site during planting in October 2022 buffer area of five metres up and downstream of the indicated

4 Landscape SA • Issue 127 2023