Estuarine and coastal saltmarsh communities are recognised as ecologically significant habitats, yet their fine‑scale spatial distribution is often poorly mapped due to the complexity and heterogeneity of vegetation across tidal gradients. This project was initiated to test the efficacy of high‑resolution, remotely sensed community‑level vegetation mapping, relative to traditional on-ground methods, in accurately mapping saltmarsh type and extent across three estuaries in Western Port Bay, near Melbourne.
High‑resolution colour‑infrared aerial imagery supplied by MetroMap was used as the primary remote sensing dataset. An Object‑Based Image Analysis (OBIA) workflow was developed in ArcGIS Pro to segment the imagery and classify multiple estuarine saltmarsh communities and mangroves. The approach incorporated spectral and elevation variables, with iterative rule‑set development informed by on‑ground ecological knowledge. Accuracy assessment was conducted using drone-imagery validation and expert interpretation.
The OBIA method successfully delineated and classified key saltmarsh functional groups and mangrove communities across the three study estuaries. The analysis produced high‑resolution vegetation maps suitable for integration into existing GIS platforms, and a reproducible classification workflow. Results revealed distinct spatial patterns in vegetation composition, as well as areas of potential change including the widely reported ‘saltmarsh squeeze’ relevant to future management.
The improved spatial detail and community‑level classification provide robust evidence base for estuary managers. The workflow demonstrates the value of high‑resolution aerial imagery and OBIA for coastal habitat monitoring and can be applied to other estuaries seeking efficient, repeatable mapping methodologies. The outputs help inform short and long‑term management planning and monitoring.