Detection of former landfills in gravel plain using geomorphometric analysis and High-Resolution LiDAR DTM

Abstract

The article represents the application of geomorphologic approach to discover the potential areas of buried waste in agricultural landscape of Ljubljana gravel plain. Some former waste disposal sites or landfills are underground sites characterized by heterogeneous old waste buried in formerly concave landforms: old inactive gravel pits or paleo-riverbeds. They form different types of anthropogenic landforms. They were primary recognized and located with the terrain visualization (analytical shading, hypsometry) of LiDAR data and in continuation with geomorphometric analysis and classification of fluvial terrain. Due to subsidence of heterogeneous waste, terrain of former landfill sites is bumpy and uncharacteristic of fluvial surface morfology or terrain. The geomorphometric analysis was applied to differentiate the anthropogenic landforms (gravel pits, filled gravel pits …) from natural alluvial landforms with combination of two geomorphometrics: multiresolution index of valley bottom flatness (MrVBF) and convergence index and high density LiDAR data. Result is the automatically derived classification of terrain in to three classes: (1) bumpy terrain, typical for areas with high terrain potential for landfill, (2) flat terrain, typical for dry paleo riverbeds and (3) »agricultural« terrain, typical for intensive fields and meadows. By comparing the results of geomorphometric analysis with the results of visual analysis the 26 of 46 visually detected anthropogenic landforms are overlapping the areas of high terrain potential for landfill and among these 8 objects were proved with geohistorical analysis of archive aerial photographs.