1 00:00:00,667 --> 00:00:02,035 It's a historic river. 2 00:00:02,035 --> 00:00:03,837 It's a big part of the history of Texas. 3 00:00:03,837 --> 00:00:06,906 Our rivers are vital to us as a water resource. 4 00:00:07,240 --> 00:00:11,945 They're vital to us for recreation, for contact with the environment. 5 00:00:12,278 --> 00:00:15,882 The South Llano is just a great place to go to either the state park 6 00:00:15,882 --> 00:00:17,450 or along the entire length of the river 7 00:00:17,450 --> 00:00:20,220 for recreation and just connection with nature. 8 00:00:21,221 --> 00:00:23,656 Anyone who's out there falls in love with it. 9 00:00:23,656 --> 00:00:26,993 On the South Llano, previously, we've had cross-section 10 00:00:26,993 --> 00:00:30,030 data that might have been collected at specific locations, 11 00:00:30,764 --> 00:00:35,602 but not a full, comprehensive survey of the entire length of of the river 12 00:00:35,602 --> 00:00:39,906 and what the entire shape of the bed banks and bottom of the river would look like. 13 00:00:39,906 --> 00:00:43,610 We're doing a riverine bathymetric study 14 00:00:43,610 --> 00:00:48,481 where we collect Lidar data of the river bottom surface 15 00:00:48,848 --> 00:00:52,052 It allows us to get a full picture of 16 00:00:52,385 --> 00:00:55,155 not only what the bottom of the river looks like but the banks and the 17 00:00:55,155 --> 00:00:56,489 surrounding area as well. 18 00:00:57,824 --> 00:00:59,125 So, Lidar is collected 19 00:00:59,125 --> 00:01:03,396 by a sensor on the bottom of a plane, which pulses a laser. 20 00:01:03,730 --> 00:01:08,868 And as that laser reflects off of the ground surfaces, we get a timing for that. 21 00:01:08,868 --> 00:01:13,306 And that timing is used to calculate the elevation of the reflected surface. 22 00:01:13,540 --> 00:01:17,677 For bathymetric Lidar collections, it's actually a different type of sensor 23 00:01:17,677 --> 00:01:19,479 than the topographic Lidar.. 24 00:01:19,479 --> 00:01:24,350 The South Llano is an excellent fit for this type of project because it is 25 00:01:24,350 --> 00:01:29,522 generally a clear water stream, and that will allow the bathymetric Lidar 26 00:01:29,722 --> 00:01:34,961 to accurately penetrate the column and get a good measurement. 27 00:01:35,295 --> 00:01:38,331 Previous traditional Lidar would just give us a flat 28 00:01:38,698 --> 00:01:41,501 elevation across the surface of the river. 29 00:01:41,501 --> 00:01:44,504 To know anything about the channel, we have to go out in the field 30 00:01:44,504 --> 00:01:45,905 to survey that data. 31 00:01:45,905 --> 00:01:48,775 It would take us a month of data collection 32 00:01:48,775 --> 00:01:52,745 to get detail in maybe a mile or two miles of river. 33 00:01:53,446 --> 00:01:55,815 With this Bathymetric Lidar collection, 34 00:01:55,815 --> 00:01:59,752 they're able in one day to collect 30 miles of river data. 35 00:02:00,320 --> 00:02:03,990 The efficiency is just fantastic in comparison to what we would do, 36 00:02:03,990 --> 00:02:05,658 collecting it by hand. 37 00:02:05,658 --> 00:02:09,929 So, in addition to acquiring the Lidar data, we also hire a third party. 38 00:02:10,096 --> 00:02:14,400 The folks on the ground are actually using survey-grade data collection. 39 00:02:14,400 --> 00:02:17,504 So, they are going and they're collecting survey-grade GPS 40 00:02:18,037 --> 00:02:20,640 data points for the bottom surfaces of the river 41 00:02:21,107 --> 00:02:25,545 to validate the elevation values that we get from the Lidar. 42 00:02:25,545 --> 00:02:27,947 Really this is foundational-type data. 43 00:02:28,047 --> 00:02:31,618 So, it's similar for a study on land, the Lidar data 44 00:02:32,285 --> 00:02:36,222 would be useful for land zoning, for any kind of development work 45 00:02:36,222 --> 00:02:39,893 that you do, rainfall, runoff modeling, any of that type of work. 46 00:02:40,260 --> 00:02:43,796 So, by adding that aspect of having the bathymetric 47 00:02:43,796 --> 00:02:47,267 or the bottom-of-the-channel data, we can now use that data 48 00:02:47,734 --> 00:02:52,038 also for flood studies; very useful information for doing a hydraulic study 49 00:02:52,038 --> 00:02:55,942 to know different flow rates; what would be the water surface elevation 50 00:02:56,643 --> 00:02:59,646 associated with those flood levels. 51 00:02:59,913 --> 00:03:04,417 If we were able to get a complete bathymetric dataset of rivers in Texas, 52 00:03:04,417 --> 00:03:07,420 that would be very helpful for flood planners. 53 00:03:07,687 --> 00:03:10,924 One of the ways, as a river scientist, that I'm excited about is just looking 54 00:03:10,924 --> 00:03:15,395 at the shape of the river and, then maybe, coming back in 10 or 20 years 55 00:03:15,762 --> 00:03:19,832 and re-flying the bathymetric Lidar, collecting that data again 56 00:03:19,832 --> 00:03:25,038 and having that comparison with over one or two decades and see how the river is 57 00:03:25,038 --> 00:03:30,376 changing--what impacts human developments may or may not be having on the river. 58 00:03:30,376 --> 00:03:35,114 And that type of analysis is only possible with a great data set like this.