AERIAL SENSORS


Detailed 3D data captured using an


aircraft mounted laser is helping RPS Group plan, design and engineer a major overhaul of


water supply in County Wicklow, Ireland.


❱ ❱ Aerial ‘laser map’ used to assess


flood risk – the colours relate to the land elevation (the area shown is Wicklow, Republic of Ireland)


LiDAR aerial survey data secures Irish water supplies


T


he Mid Wicklow Water Supply Scheme aims to address issues of water quality, limitations of source availability and issues with treatment plants. Announced in 2016, Irish Water proposes upgrading the Vartry Water treatment plant after


supplies were identified by the Environmental Protection Agency as being at risk of failing to meet the requirements of national safe drinking water standards. As part of the project, supply to seven existing water supply zones are to be rationalised, with individual sources and treatment plants decommissioned and a single source of supply from the Vartry Water treatment plant established. Irish planning, design, engineering, environmental and communications services consultancy RPS Group commissioned a LiDAR survey from Bluesky in order to fully understand the topography of the region. The data is being used to assess route and pressure control options as a result of high pressures in the trunks mains. Three alternative route options are being assessed in order to determine the most favourable, including two alternative trunk main routes and relocation of the Rathdrum Reservoir. Bluesky Ireland is a specialist in aerial survey using state- of-the-art technology including LiDAR to capture and process aerial photography, with high speed of capture coupled with high accuracy. LiDAR as a surveying method measures distance to a


target by illuminating the target with pulsed laser light and measuring the reflected pulses with a sensor. Differences in laser return times and wavelengths can then be used to make digital 3D representations of the target. The name LiDAR is an acronym of light detection and ranging. The technology is commonly used to make high-resolution maps, with applications in geodesy, geomatics, archaeology, geography, geology, geomorphology, seismology, forestry, atmospheric physics, laser guidance, airborne laser swath


6 /// Aerospace Test & Validation 2018


mapping (ALSM), and altimetry. The technology is now also used in control and navigation for some autonomous cars. Having begun an ambitious national data capture


programme in 2015, Bluesky Ireland has captured high resolution aerial photography of a significant area of the country, with surveying expected to be completed this year. Bluesky Ireland is already working with many high-profile organisations in the Irish geospatial market including the Department of Agriculture, Food and the Marine, the Department of Culture, Heritage and the Gaeltacht, the Geological Survey of Ireland and the state forestry company Coillte, as well as a host of local authorities. The LiDAR data from BlueSky is being used to assess


various route options as water supply in the region south of Dublin is rationalised. The Bluesky data is also used to enhance topographical surveys in order to understand and mitigate the risk of flooding in relation to additional water supply infrastructure. “Bluesky uses the latest aerial survey technology in order to capture LiDAR data to exactly meet the requirements of a specific project,” says Saeed Khan, Technical Director, RPS Europe. “The density and accuracy of LiDAR makes it ideal for this type of project giving unrivalled measurement of the earth’s surface and natural and man-made structures.” Bluesky LiDAR data is also used to enhance and supplement


topographical surveys and culvert information collected by RPS engineers. In line with Planning System and Flood Risk Management Guidelines, published by the Office of Public Works and the Department of Environment Heritage and Local Government, RPS undertook a Flood Risk Assessment to support the planning application for the project. To calculate flood levels for different levels of risk, the Bluesky and RPS survey data are used to create a hydraulic model developed in Infoworks ICM (Integrated Catchment Modelling). This is in turn used to develop a flood extents map. n


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