Oral Presentation Freshwater Sciences 2023

Applicability of combined remote sensing and geomorphic approach to the assessment of surface water connectivity in Queensland floodplain wetlands.   (#43)

Maria Julieta Rossi 1 , Laurisse Luke 1 , Glenn Mcgregor 1 , Willem Vervoort 2
  1. Water Planning Ecology I Department of Environment and Science, Queensland Government, Brisbane
  2. School of Life and Environmental Sciences | Sydney Institute of Agriculture, THE UNIVERSITY OF SYDNEY, Sydney

Surface water connectivity between rivers and floodplain wetlands is essential to maintain biodiversity and ecological functioning in floodplain wetlands. However, extreme weather events, such as long droughts and climate change have impacted the connectivity and ecosystem functioning of floodplain wetlands. There has therefore been a rise in the awareness to maintain and restore water exchange between rivers and floodplain wetlands to support the aquatic biota. Yet, it is technically challenging to find the connection pathway for the wetlands that are located at a distance from the main river channel. This challenge is exacerbated by the fact that optical-based remote sensing (RS) techniques have limitations while mapping surface water extent located below vegetation canopy, such is the case of many floodplain wetlands in Queensland. The use of geomorphology can aid optical-based RS by the identification of topographic depressions (areas that are geomorphologically prone to inundation) and extend the surface water extent detected through RS to these technically challenging areas. We propose to test the applicability of a previously developed method that combines the use of optical-based remote sensing and a geomorphic approach to map surface water, find connection pathways between wetlands and rivers, and to estimate their hydrological connectivity. The methodology was applied to several Queensland wetlands that had presence of surface water under vegetation by using freely available remote sensing and Lidar data. Results support initial findings that the use of Lidar data is useful to fill existing gaps in remote sensing applications. The connection pathways of the Queensland floodplain wetlands to the river were identified and surface water extent and hydrological connectivity resulted in higher values when compared to results obtained using sorely RS. These findings have implications on the estimation of hydrological connectivity, flow thresholds representing filling of floodplain wetlands and the formulation of surface water management policies.