School of Earth & Environmental Sciences
Bowie, Catherine, Mangrove and saltmarsh dynamics in Homebush Bay: implications for management at Sydney Olympic Park, BEnviSci Hons, School of Earth & Environmental Sciences, University of Wollongong, 2015.
Mangrove and saltmarsh wetlands generally occur at the interface of terrestrial and marine ecosystems. Prior to the 1980’s, coastal wetlands, including those in urban areas, were regarded as wastelands of little value; however, since then the ecosystem services they provide have been recognised. Urban wetlands face a range of challenges, most often reclamation for coastal development and poor ecosystem health. The Badu Wetland in Sydney Olympic Park, NSW, Australia, has been impacted by multiple pressures associated with wetlands in urban environments.
This study aims to identify the relationship between coastal wetland health and distribution, and water levels. Particular emphasis was given to the effect of previous management interventions on current health and distribution, and the projected influence of sea-level rise in the 21st century. This was achieved by 1) collating information about past and present vegetation changes, policies to ameliorate vegetation change, and future threats to vegetation health; 2) mapping the current wetland distribution, and establishing the degree of change from previous mapping; 3) modelling the relationship between wetland vegetation distribution and elevation using digital elevation models; 4) establishing the vertical accretion and surface elevation trends using an established network of surface elevation tables and marker horizons; and 5) exploring the relationship between elevation and accretion trends and environmental variables, such as elevation, distance from the channel and hydroperiod.
It was found that the Badu Wetland had poor mangrove health, including mangrove dieback, and this is linked to poor tidal flushing, either through long flow lengths or slight depressions within the landscape causing pooling of tidal waters. Vegetation distribution of mangrove and saltmarsh has remained relatively stable since 2002, and surface elevation and accretion trends over this period within both the mangrove and saltmarsh exceeds current rates of sea level rise. However, these rates may lag behind projected rates of sea level rise for the 21st century.