This week: Flooding in central Jakarta and resources, levee deficiencies in the U.S., and how accurate LiDAR is.
Central Jakarta Goes Under: A Flood Survivor’s Account (Jakarta Globe)
The events of this week caught us, our neighbors and all of Jakarta off guard. Throughout Wednesday night and early Thursday morning, it rained heavily, and my housemates and I only worried about our precariously patched up roof.
We all planned to go to work on Thursday morning, albeit a bit late on account of the heavy rain…
…For such a big event, the actual flooding and evacuation happened so quickly. It only took four hours from the start of the water flowing into the house until we were settled into our temporary accommodations…
…Returning to the house the next day, our spirits weren’t as high. There was no electricity and no running water. A thick layer of mud covered the ground and everything else that had been submerged in the dirty water. Again, we reminded ourselves that things could be replaced, but it was still disheartening to see our books, photos, clothing and other treasured belongings completely destroyed.
Twenty people are confirmed dead and 50,000 are homeless after days of severe flooding in the Indonesian capital Jakarta.
A weekend of relatively fine weather has helped the city recover in some parts, but there are still areas that are completely under water.
On Thursday, 17 January 2013, torrential rain has caused massive flooding in the Jakarta Capital Region, Indonesia, virtually shutting down the city. We will continue to update this page with maps, links, and other useful resources.
7 years after Katrina, inspectors finding dangerous deficiencies in US levees (Washington Post)
Levees deemed in unacceptable condition span the breadth of America. They are in every region, in cities and towns big and small: Washington, D.C., and Sacramento Calif., Cleveland and Dallas, Augusta, Ga., and Brookport, Ill.
The U.S. Army Corps of Engineers has yet to issue ratings for a little more than 40 percent of the 2,487 structures, which protect about 10 million people. Of those it has rated, however, 326 levees covering more than 2,000 miles were found in urgent need of repair.
Just How Accurate is LiDAR? (LiDAR News)
In conversations with experts at Riegl I learned two important things. First, the published specifications are actually quite conservative. Second, they have LiDAR sensor operators that do deliver bare earth point clouds with vertical accuracies that exceed the printed specifications. So it has been established in practice that it is possible. However, because the operation of these systems and the processing of LiDAR data is fraught with error in unskilled hands, it is far easier and, unfortunately, more common that LiDAR data is delivered that does not meet project specifications (whether they are tested or not). For those purchasing professional LiDAR services, you are well advised to know your provider and “trust but verify” that their deliverables meet your specifications. Depending on the intended use of the data, it is often advisable to verify the accuracy of the deliverables to specific standards.