High-resolution environmental monitoring: A determination of the upland swamp-woodland boundary from ALS (airborne laser scanning) data

Le résumé fourni par la source

Upland swamps are important features of the Woronora Plateau and elsewhere in the Sydney Basin. The swamps occur on peaty accumulations within Triassic sandstone shallow groundwater fed catchments. Swamps are identified as environmentally sensitive landscape features that require monitoring as part of Subsidence Management Plans. However, swamp condition (extent, phytosociology) is naturally variable and significant change is identified over decadal timeframes as a response to wildfire, drought cycles, high intensity rainfall events and longer-term rainfall patterns. Current mapping methods do not provide the resolution necessary for change detection in the shorter term, especially where discrimination may be required between subsidence-related impact and natural processes. A notable feature of upland swamp vegetation is their strong vertical contrast with the surrounding woodland or forest. Here I present a high-precision method to locate swamp-woodland boundaries using airborne laser scanning (ALS or LIDAR: Light Detection and Ranging). The resultant monitoring line is distinctive, visually interpretable and can be reproduced using quantitative methods. As such, the monitoring line can form a benchmark for detecting small changes in the swamp boundaries. The ALS-based monitoring method adds value to an emerging subsidence-monitoring technology, and is especially applicable in areas of rugged or difficult terrain.

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