The ISC2010_VEGETATION_OVERHANG polygon features represent areas of vegetation that partially or wholly overhang the Stream Bed. The data set contains the whole vegetation polygon, not only the overhanging part of the polygon. Candidate vegetation is defined as vegetation cover greater than 20%. Vegetation Overhang has been mapped within a 200m buffer of the ISC2010_STREAMBED_WIDTH feature. This data set is derived from source Fractional Cover raster data. The data set also contains additional polygon divisions created by the introduction of Side and 200m buffer boundaries. Small polygons (<10m2) that were created by the introduction of these boundaries have been removed.
River condition in Victoria is assessed every 5 years using the Index of Stream Condition (ISC). The Department of Environment and Primary Industries (DEPI) developed a methodology to assess the Physical Form and Riparian Vegetation components of the ISC using remote sensing data, specifically LIDAR and aerial photography.
A State Wide mapping project was undertaken in 2010-13 to accurately map the Physical Form and Riparian Vegetation metrics of the ISC . Other ISC metrics were not assessed in the project and were derived from other sources.
The Physical Form and Riparian Vegetation Metric products are a combination of mapped Vector and Raster data as well as Tabular Summary Statistics about the mapped features. In the context of the project, the term Metrics is used to refer to both the mapped features and the summary statistics.
Remote sensing data used includes 15cm true colour and infra-red aerial photography and four return multi-pulse LiDAR data. This source data was used to derive a variety of Raster data sets including Digital Terrain Models, Slope, Vegetation Height and Vegetation Cover. The Digital Terrain and Slope rasters were used to map Physical Form metrics including Stream Bed, Top of Bank and River Centre Lines while the Vegetation Height and Cover rasters were used to map the Riparian Vegetation metrics.
The Project Report "Aerial Remote Sensing for Physical Channel Form and Riparian Vegetation Mapping" describes the remote sensing and mapping approach used to create this data set.