Why You Should Care About Pennsylvania’s New QL2 LiDAR Elevation Data
17 May 2019

Why You Should Care About Pennsylvania’s New QL2 LiDAR Elevation Data

Emily Constantine Mercurio, PhD, PG

17 May 2019

For data nerds like me, the availability of (FREE!!!) Quality Level 2 (QL2) LiDAR Data in Pennsylvania is extremely exciting. For those of you who are unfamiliar with this technology, LiDAR (Light Detection and Ranging) is a form of data capture whereby a laser is used to measure the distance and position of a target. To collect statewide elevation data, the laser scanner is mounted on an aircraft and as the plane flies, the scanner very rapidly dispatches laser light to the Earth’s surface, records the returned signal from the reflected points, and calculates an elevation and geographic location for each point. After a heavy dose of data processing, the result is a 3D “cloud” of points that is used to construct a continuous digital model of the surface within a few centimeters of accuracy. The QL2 version of this technology promises more accurate and better data quality compared to older LiDAR systems. If this all sounds amazing to you, that’s because it is!

Pennsylvania's 3D QL2 LiDAR elevation data provide a basis for modeling the flow of water over the Earth’s surface. 

Map of Current Status of Quality Level 2 LiDAR data in Pennsylvania, March 2019 Current Status of Quality Level 2 LiDAR data in Pennsylvania, March 2019

So, why should you care about these elevation data? One big reason is because these 3D QL2 LiDAR elevation data provide us with a basis for modeling the flow of water over the Earth’s surface. This of course is very important for understanding which locations are prone to flooding and how to better manage stormwater. But this is especially critical in urban areas where stormwater runoff from impervious surfaces like pavement, cement, and rooftops causes problems for people, property, and the environment. Using LiDAR elevation data as a basis for our models, we can show where stormwater collects, what direction it will go, and how much will accumulate at any given point based on factors like topography, slope, and other physical parameters. Further, our models can also help to identify locations for installing green infrastructure like bioretention basins that capture water before it becomes a problem.

At CivicMapper we are taking the use of LiDAR elevation data for stormwater one step further by using high definition mapping (HDmaps) from unmanned aerial vehicles (e.g., drones) and autonomous vehicle systems (like the kind used on self-driving cars, some of which are themselves LiDAR-based). This allows us to create even more detailed representations of the urban environment. With these HD map data, we can more accurately model how flowing water will interact with stormwater infrastructure like storm drains, curbs, road crowns, and other roadside features. But in order to make this HD mapping method possible, we need high quality LiDAR elevation data to provide information in non-urban areas or where HD data are not available. This is just one way that the QL2 LiDAR data are inspiring companies to innovate and create new ideas for solving real problems.

In the same way we can use LiDAR elevation data to model the flow of stormwater over the Earth’s surface, we can also calculate the steepness of slopes and identify locations where landslides are more likely to occur. 

Here in Pennsylvania, we know that where there are hills and water, there are landslides. In the same way we can use LiDAR elevation data to model the flow of stormwater over the Earth’s surface, we can also use it to calculate the steepness of slopes and identify locations where landslides are more likely to occur. The Earth’s surface changes quickly due to development, erosion, and previous landslide events, and the new LiDAR elevation data will make it easier to detect changes in terrain by serving as a basis of comparison with older PA LiDAR data sets. These new insights will help us to qualify geologic risk, draw attention to current landslide-prone areas, and better understand how stormwater runoff may be making an unstable slope even worse.

The applications of LiDAR elevation data are numerous. While I’ve only touched on a few of them here, I hope I’ve got you excited about this amazing data resource. Not only do these data provide us with information about Pennsylvania’s terrain, they are also providing businesses with a free resource we can use to create new and innovative applications and products that help people mitigate the damaging effects from an increasingly wetter climate. Thank you Pennsylvania!



This post originally appeared on LinkedIn

CivicMapper is a geospatial information services and technology company that helps clients to leverage their geodata assets for mission success. Get in touch via info@civicmapper.com.