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GCN : April 2013
shows the extent of the flooding." Fritz said the LIDAR data can be com- bined with all sorts of other data. It can, for example, be used to determine where and to what extent nutrients will flow in irrigated fields. "We're talking about efficiencies here, where we can get the most bang for the buck, whether it's a flood damage reduc- tion project or water quality project or natural resource enhancement project," he said. "All of that is predicated on the LIDAR data." When he started the project, Fritz felt like he was a voice in the wilderness. He spent a year and a half trying to convince people that the project was important to them. "Now," he said, "I can tell you that with no exceptions the people who have experience with the data that we have collected are all saying that it is the best thing since sliced bread. Even most local watershed districts will not start a meet- ing unless they have that LIDAR viewer open on the table." While Fritz's team is focused on build- ing more applications to use the data, they are also looking forward to a fresh collection of data. "Since we completed data collection in 2009," he said, "there's been a lot of work, especially in the major metropolitan areas. Fargo, Grand Forks. They put up flood dikes, etc., so now we are talking about how we're going to up- date the current LIDAR data set." RUGGED OREGON FROM THE AIR If flatness is a hydrological challenge in the Red River Basin, rugged terrain is a major challenge in Oregon. Feet-on-the- ground surveys of forest inventories, for example, are particularly time-consum- ing and, therefore, expensive and quick- ly outdated. Scanning from the air is much less costly. "It ends up being about as offset- ting costs," said Oregon's John English. "It is allowing people to save money on these long surveys." With two specialists -- English and one other scientist collecting and organizing the data -- the state of Oregon covers be- tween 5,000 and 7,000 square miles per year at a cost of $3 million to $4 million. So far, the team has collected LIDAR data on 26 percent of the state, focusing first on the more heavily populated western half. The state also has approximately 25 GIS analysts working with the data for a variety of agencies and purposes. The airborne LIDAR fires eight points per square meter, more than 100,000 pulses per second. According to Eng- lish, that's enough to ensure that even in dense forest, some of the points reach the ground. Comparing the distances of puls- es reflected off the tree tops and those reflected off the ground allows the team to calculate the heights of trees very accu- rately. And not only that, the full array of returned pulses allows the team to survey undergrowth, too. Oregon's LIDAR efforts, of course, aren't restricted to forest inventories. In fact, the first use of LIDAR was a joint ef- fort of the state's Department of Geol- ogy and Mineral Industries and the U.S. Geological Survey to conduct a landslide study in the Portland area in 2004. They also use the data for habitat analysis assessment. "People are finding more uses for it," English said. "Municipal mapping of streets, measuring volumes for displaced sediment, flood mapping, hazard map- ping. You can even detect wear and tear on roads. It can do a rough survey on everything in an entire city. If you have a house and you know its height, and there's a flood, we can infer how many houses are totaled according to FEMA. Right now we're producing the most accu- rate flood-inundation maps ever made." English says the plan is to scan the en- tire state. "But we're trying to do it in a methodical way. Primary areas of interest are places where work is being done and where humans interact with the environ- GCN APRIL 2013 • GCN.COM 25 LIDAR MEETS THE COASTLINE The U.S. Army Corps of Engineers is currently on its second LIDAR data-gathering e ort covering the nation s shorelines. Employing both topographic and bathymetric LIDAR in aircraft, the Corp s National Coastal Mapping Program scans the shoreline --- including Hawaii, Alaska and the Great Lakes --- in a swath 500 meters inland and 1,000 meters o shore. At current funding levels, the team can cover the entire shoreline every five to six years. Chris Macon, technical lead for program, says that the primary purpose of the program has been to track the movement of sand to ensure safe navigation of the country s waterways. "We re finding out how much sand there is, where it is, where is it moving to along the coast and how it is impacting federal navigation projects," said Macon. According to Macon, the airborne bathymetric LIDAR delivers accuracy of 25-30 centimeters vertical accuracy, and its maximum penetration is roughly 50 meters in crystal-clear waters. Increasingly, Macon says, while navigation issues are still the priority, as LIDAR scanning and analysis has gotten more accurate and applications have proliferated, federal, state and local agencies are asking for more coverage inland. "As our capabilities have grown, adding topographic LIDAR, adding true color imagery and adding hyperspectral imagery, people want more coverage inland," he said. In addition to navigation issues, Macon says the data is being employed for invasive species mapping, impacts on wetlands and post-hurricane assessments.