Estimating underwater features of channel bed surfaces without the use of bathymetric sensors results in very high levels of uncertainty. A novel approach to create more accurate and detailed Digital Terrain Models (DTMs) integrates LiDAR-derived elevations of dry surfaces, water depth of wetted areas derived from aerial photos and a predictive depth-colour relationship. This method was applied in three different sub-reaches of a northeastern Italian gravel-bed river (Brenta) before and after flood events occurred in November and December 2010 (recurrence interval: 8 and 10 years). From the data collected through channel field survey, a regression model which calculates channel depths using the correct intensity of three colour bands was implemented. LiDAR and depth points were merged and interpolated into a DTM which features an average error of ±18 cm. The morphological evolution and the sediment volume change calculated through a difference of DTMs shows deposition and erosion areas, indicating a deficit which reduces as it goes downstream.

Assessing morphological changes in gravel bed rivers using LiDAR data and colour bathymetry

MORETTO, JOHNNY;RIGON, EMANUEL;MAO, LUCA;DELAI, FABIO;PICCO, LORENZO;LENZI, MARIO ARISTIDE
2012

Abstract

Estimating underwater features of channel bed surfaces without the use of bathymetric sensors results in very high levels of uncertainty. A novel approach to create more accurate and detailed Digital Terrain Models (DTMs) integrates LiDAR-derived elevations of dry surfaces, water depth of wetted areas derived from aerial photos and a predictive depth-colour relationship. This method was applied in three different sub-reaches of a northeastern Italian gravel-bed river (Brenta) before and after flood events occurred in November and December 2010 (recurrence interval: 8 and 10 years). From the data collected through channel field survey, a regression model which calculates channel depths using the correct intensity of three colour bands was implemented. LiDAR and depth points were merged and interpolated into a DTM which features an average error of ±18 cm. The morphological evolution and the sediment volume change calculated through a difference of DTMs shows deposition and erosion areas, indicating a deficit which reduces as it goes downstream.
Erosion and Sediments Yields in the Changing Environment
9781907161339
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11577/2749284
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