Quantifying riparian vegetation and stream bank form through the use of airborne laser scanning and digital video data

A methodology for a cost-effective and detailed assessment of the riparian zone of segments (/spl sim/30 km) of the Brisbane River and Lockyer Creek in Queensland, Australia is described. Digital terrain models (DTMs) of the stream banks as well as detailed maps of the riparian vegetation type and structure were produced using airborne laser scanner and digital video data. The methodology is applicable to almost any stream or river system worldwide. DTMs of the river banks and adjacent land approximately 100 m from the waters edge were produced from the laser scanner data with an accuracy of 30 cm or better for 80% of the data. Open areas with little understorey or grass cover tended to be accurate to approximately 10 cm. Vegetation maps at a scale of approximately 1:4,000 were produced. Each clump of shrubs or small trees as well as larger individual trees were delineated and attributed with species, weed infestation levels, height and foliage projected cover (FPC) values. The vegetation mapping was completed through classification of the laser data and manual interpretation of the video imagery supported by field verification. The accuracy of the floristic components of the vegetation map is estimated to be approaching 100% although validation has not yet been completed. The spatial accuracy of vegetation polygons delineated is approximately one meter. The laser data as captured for this project allows for maps to be produced at a scale of 1:1000.