What existing wetland classification systems do not tell us: Implications for restoring wetlands in drylands and a proposal for a genetic geomorphic classification system

Suzanne Grenfell

Publication Date:

Due to climatic constraints in dryland regions, wetlands usually occur at confluences of flow paths, whether from surface flow, inter-flow, or occasionally at locations of groundwater discharge. Long-term landscape processes that shape valleys and focus the movement of water and sediment are accountable for providing a suitable template with which hydrology interacts to allow wetland formation. Understanding the temporal and spatial scales of these dynamics, as well as the drivers behind them, is key to successful wetland management and rehabilitation. Existing wetland hydrogeomorphic classification systems focus on hydrology, which is an outcome of interactions of geomorphology and climate. These systems typically neglect the role of sediment accumulation in maintaining wetlands in drylands, or potentially shifting the system from one of aggradation to one of erosion by crossing slope thresholds. A classification system is proposed that focuses on mode of wetland formation and is based on the understanding that genetic processes impact on the outcome hydrology, sedimentology, geomorphology, ecosystem service provision, and long-term dynamics of wetlands in drylands. The classification aims to impart understanding of dynamic processes of sediment transport in wetlands, such that restoration plans can be sensitive to long-term landscape processes. The classification system, developed primarily for wetlands in southern Africa, has four wetland macrotypes based on sediment source (colluvial, alluvial, aeolian and geochemical), which may be subdivided into 8 wetland types based on landscape location, shape and the occurrence of geomorphic characteristics indicative of process (hillslope seep, floodplain, valley-bottom, plain, blocked-valley, alluvial fan, aeolian depression and geochemical depression).

Resource Type:
Audio/Video, Conference Presentation, SER2019

Pre-approved for CECs under SER's CERP program

Society for Ecological Restoration