Use of aerial multispectral images for spatial analysis of flooded riverbed-alluvial plain systems: the case study of the Paglia River (central Italy)

Abstract

Image processing and classification techniques are widely used for land use definition. They can also provide interesting applications in fluvial geomorphology, for outlining morpho-sedimentary features (bars, channels, banks and floodplain) at various temporal stages, in order to monitor the evolution of river systems. Frequent monitoring is especially important for streams, in terms of flood risk in urban areas. This study shows how techniques of supervised analysis can be applied to river systems, also under particular conditions, like after flood events (when large portions of riverbed and alluvial plain are covered with mud). The procedure starts from the classical photogrammetric techniques, based on multispectral classification, and goes on with post processing operations of pixel aggregation and shadow treatment. The classification also uses the elevation information provided by Digital Surface Model produced by photogrammetry. This paper introduces a new technique of remote sensing in fluvial areas that allows for both the identification and classification of the fluvial features in a post flooding condition. Application of the procedure over time permits the evolution of the fluvial dynamics to be monitored in an accurate and inexpensive way, particularly for flood event conditions which lead to major changes in the dynamics of riverbeds.

A GIS-Based Tool for Automatic Bankfull Detection from Airborne High Resolution Dem

“…Determining bankfull dimensions in the fields may be difficult for streams that are in disequilibrium or rather for riverbeds that are recently carved or are still under a linear incision process. Most geomorphological studies require the detection of bankfull dimensions and often data collected in the field have to be interpreted and combined with remotely sensed data [19,20]. Disequilibrium channels are typically hydrologically disconnected from their active-floodplain with a development of in-channel morphological feature (i.e., benches and incipient floodplain) [21,22].…”

U-Net-Based Multispectral Image Generation From an RGB Image

“…where G(F′) represents the activation of the output image F′ through the VGG16 pre-trained network, and the other notations remain the same in as in (1).…”

“…Because multispectral images have more spectral information than RGB images, spectral analysis is an important research method in the natural sciences. It plays an important role in geological research [1], cultural heritage protection [2], [3], and astronomical research [4]. Spectral technology can detect the physical structure and chemical composition of measured objects.…”

Image Processing of UAV Imagery for River Feature Recognition of Kerian River, Malaysia

“…Supervised image analysis consisting of classical image processing techniques such as multispectral classification along with pixel aggregation and shadow treatment is useful for analyzing flooded riverbeds [17]. Digital image processing is also functional as regards historical archives of river imagery to capture features of interest [18] as well as for LiDAR images [19]. Image processing of webcam images utilizing Raspberry-Pi and optical sensors is handy for flood detection [20].…”