Rethinking wetland restoration by considering natural dynamics: Evidence from the Krom River unchannelled valley-bottom wetland, Eastern Cape

Authors:
William Ellery

Publication Date:
2019

Abstract/Summary:
Wetland restoration in the global and South African contexts traditionally considers the hydrological regime as the primary driver of physio-chemical processes that influence wetland ecosystem structure and function. However, in a dryland situation such as South Africa that is dominated by weathering over timescales of tens of millions of years and erosion processes as a consequence of sub-continental uplift over the last 30 million years, geomorphological processes governed by flowing water play a key but largely unrecognised role in shaping the landscape to host wetlands, fundamentally influencing wetland structure and function. As such, the geomorphic work of flowing water and its benefits for wetland formation and maintenance has not before been incorporated into wetland restoration efforts. The Krom River wetland highlights the range of processes in an erosional landscape that contribute to creating a landform well suited to host wetlands. Erosion events happen at intervals of hundreds of years, which leads to both longitudinal slope reduction and valley widening. Erosion is associated with deposition of a gully-fan at the toe of the gully, which happens over timescales of years to decades. It is proposed that this variation in hydrodynamic and geomorphic processes, operating over different time scales, have contributed to the limited success of the large-scale engineering structures that have been put in place as part of wetland restoration activities in the area. It is argued that restoration activities need to incorporate hydrodynamic and geomorphic processes that work with, rather than in opposition to, the natural dynamics of the system.

Resource Type:
Audio/Video, Conference Presentation, SER2019

Pre-approved for CECs under SER's CERP program

Source:
Society for Ecological Restoration