We love LiDAR!

3D visualisation of predicted flooding in Point Samson

Over the last 12 months Essential Environmental has come to form a special bond with LiDAR (a combination of light + radar) – a remote sensing technology that uses laser pulses to generate large amounts of data about the physical layout of terrain and landscape features.

To obtain LiDAR data an instrument and mounted sensor is aimed over an area of interest, allowing the fire of rapid pulses of light (laser pulses) at the landscape.  The sensor measures the amount of time taken for each light pulse to bounce back. Because light moves at a constant and known speed, the lidar instrument can then calculate the distance between itself and the target with high accuracy.

By rapidly repeating the process, the lidar instrument builds up a complex ‘picture’ of the terrain it is measuring.

LiDAR sensors may either be fixed, ground-based sensors, or moving sensors, attached to satellites and aircraft.  For aircraft-based LiDAR, the instrument is typically mounted below the aircraft.  To ensure data accuracy, the airborne instrument needs to always know its precise location as it moves, which is usually achieved by through the provision of GPS positional information and aircraft pitch data.

LiDAR has a great many applications ranging from archaeology (including the recent discovery of Mahendraparvata, a lost mediaeval city in north-western Cambodia), agriculture, forestry, geology, robotics, meteorology and astronomy. In September, 2008, NASA’s Phoenix Lander used LiDAR to detect snow in the atmosphere of Mars.

Discovery of Thom Dab temple of the lost city of Mahendraparvata (Source: http://www.smh.com.au/national/jungle-surrenders-its-lost-city-20130614-2oa9b.html)

Whilst not getting to trek through the Cambodian jungle, the Essential Environmental team has taken advantage of this rather powerful technology to accomplish a number of tasks, including the creation of contours to obtain detailed topography data and Digital Elevation Maps, watershed analysis, and 3D visualisation of catchments, streams and floods. These analyses have then allowed us to undertake complex hydraulic and hydrological modelling using both DRAINS and InfoWorks software. Hydraulic modelling of the Harding River in Roebourne and 3D visualisation of flooding in Point Samson in the Pilbara are examples of our most recent LiDAR-based mastery.

Our relationship with LiDAR is currently flourishing as we use it to model the hydrology of the Yakamia river for the City of Albany.

3D visualisation of the Yakamia watershed, Albany

Using LiDAR data in hydrology and drainage studies has a number of advantages. It can be used instead of survey data for hydraulic and hydrological modelling, which is particularly useful if survey data is not available or cost-prohibitive. It also allows us to more  efficiently delineate catchments using GIS software, which ordinarily would have to be defined using the more traditional hand-drawn technique! This in turn improves the accuracy of hydraulic and hydrological analyses relying on both catchment definition and node location.

If anyone would like to get more information on how we can use LiDAR to help you with a project, please feel free to contact us!

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