Network Rail Bathymetry Survey River CalderRiver Calder After the successful initial 3D terrestrial scans of Whalley Viaduct, Network Rail requested an additional survey. This involved conducting a Bathymetry survey of the River Calder bed. This survey aims to investigate any potential issues related to the viaducts' crossing of the river Calder.Whalley ArchesThe Whalley Arches hold significant importance as crucial components of this busy railway route. Constructed between 1846 and 1850. The viaduct consists of 48 arches, over 600 yards long, and 70 feet above the valley. It is worth noting that the viaduct not only spans across land for a significant portion of its length but also crosses the river, adding to its unique architectural and engineering features.BathymetryTo ensure the viaduct's integrity over the river Calder, a bathymetry survey was conducted. The survey mapped a 100m river section using a HyDrone RCV remote control survey platform and the HydroLite-TM portable echo sounder kit. By connecting the HyDrone RCV to a GNSS receiver, precise geo-location of points on the riverbed was achieved. This GNSS data greatly aids in constructing the 3D river model. Furthermore, the receiver was linked to a LIDAR survey of the riverbanks. The resulting scan data accurately builds a profile of the river beneath the viaduct. Monitoring erosion and scourMonitoring the riverbed around the structures is crucial. The main focus of viaduct base failure is the flood-prone and scour-prone areas. Changes in river hydraulics due to flooding, climate change, and increased rainfall can lead to severe issues for the structures' base. This survey specifically targeted riverbed scour, detected using our high-resolution sonar bathymetric remote-control platform.Data CollectionOur bathymetric underwater surveying technology enables engineers to inspect water retention and riverbed features. They use specialised software back at our base to analyse the collected data. This data characterises the River Calder location both above and below the waterline. Furthermore, we visualise the impact of objects on river flow and assess the changes caused by sediment dynamics in the river.The captured bathymetric data provided precise resolution and detail of the area. This improved sonar detail increased the evaluation of the watercourse and facilitated the inspection and assessment of the viaduct features, ensuring the structure's safety by identifying areas of concern.Network Rail will utilise the 3D and assessment models to evaluate future maintenance needs and determine any necessary remedial works.