Managing dynamic freshwater ecosystems with the competing demands of built environments and biodiversity: An assessment of the rehabilitation of the Dawidskraal wetlands, South Africa

Authors:
Elizabeth Day

Publication Date:
2019

Abstract/Summary:
This paper considers some of the challenges affecting rehabilitation projects where protection of urban infrastructure that potentially compromises ecosystem function and sustainability is required in an area with high conservation value. It provides critical assessment of the outcomes of major structural interventions and early-stage evaluations of rehabilitation outcomes. The Dawidskraal wetlands are extensive valley-bottom wetlands, dominated by palmiet – a South African endemic. The wetlands lie within the Harold Porter National Botanical Gardens in Betty’s Bay on land largely owned and managed by the South African National Biodiversity Institute (SANBI).  Complicating their management is the heritage of inappropriate past development, resulting in residential floodplain development and a restaurant, parking area, and other infrastructure within the botanical gardens. In 2005, a large flood resulted in severe erosion of this infrastructure, collapse of an old diversion structure downstream, and the passage of a major portion of wetland flows out of the extant channel and onto a nearby road. The road surface eroded into a deep channel that thereafter conveyed most of the upstream flows, wreaking tremendous damage during subsequent flood events and perpetuating long-term disturbance to important ecosystems, while droughting the wetland. Interventions considered historical photographs and data as well as modeled flood flows. Implemented in 2018, interventions included a flow diversion structure and flood control berm and had to meet challenges around methods to sustain aquatic ecosystems in the eroded flood channel and control invasive indigenous vegetation in places, while being cognizant of local community concerns and safeguarding existing infrastructure.

Resource Type:
Audio/Video, Conference Presentation, SER2019

Source:
Society for Ecological Restoration