Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for...
-
Upload
kurt-wiswell -
Category
Documents
-
view
224 -
download
2
Transcript of Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for...
![Page 1: Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for bathymetric processing Ben R. Hodges Dept. of Civil,](https://reader038.fdocuments.us/reader038/viewer/2022102805/5517e63f550346c1568b4730/html5/thumbnails/1.jpg)
Hydrodynamic modeling for river delta salt marshes using lidar
topographyA Cell-Edge technique for bathymetric processing
Ben R. HodgesDept. of Civil, Architectural, and Environmental
EngineeringUniversity of Texas at Austin
1
![Page 2: Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for bathymetric processing Ben R. Hodges Dept. of Civil,](https://reader038.fdocuments.us/reader038/viewer/2022102805/5517e63f550346c1568b4730/html5/thumbnails/2.jpg)
The lidar challenge for hydrodynamics
• Processed lidar at 1x1 m resolution• Hydrodynamic models at 10x10 m or coarser.• Simple averaging loses information.• Ho do you handle subgrid data?• Today we’ll look at an example of
topographical processing for hydrodynamic representation.
2
![Page 3: Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for bathymetric processing Ben R. Hodges Dept. of Civil,](https://reader038.fdocuments.us/reader038/viewer/2022102805/5517e63f550346c1568b4730/html5/thumbnails/3.jpg)
Where we are working...
Texas coastimage from Google Earth
3
![Page 4: Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for bathymetric processing Ben R. Hodges Dept. of Civil,](https://reader038.fdocuments.us/reader038/viewer/2022102805/5517e63f550346c1568b4730/html5/thumbnails/4.jpg)
Where we are working...
Corpus Christi
Houston
image from Google Earth
4
![Page 5: Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for bathymetric processing Ben R. Hodges Dept. of Civil,](https://reader038.fdocuments.us/reader038/viewer/2022102805/5517e63f550346c1568b4730/html5/thumbnails/5.jpg)
Where we are working...
Nueces River Delta
City of Corpus Christi
image from Google Earth
5
![Page 6: Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for bathymetric processing Ben R. Hodges Dept. of Civil,](https://reader038.fdocuments.us/reader038/viewer/2022102805/5517e63f550346c1568b4730/html5/thumbnails/6.jpg)
Nueces River Delta
image from Google Earth
6
![Page 7: Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for bathymetric processing Ben R. Hodges Dept. of Civil,](https://reader038.fdocuments.us/reader038/viewer/2022102805/5517e63f550346c1568b4730/html5/thumbnails/7.jpg)
7
1 x 1 m ~ 120 x 106
10 x 10 m ~ 1.2 x 106
30 x 30 m ~ 130,000
data processed by J. Gibeaut, Texas A&M Corpus Christi
![Page 8: Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for bathymetric processing Ben R. Hodges Dept. of Civil,](https://reader038.fdocuments.us/reader038/viewer/2022102805/5517e63f550346c1568b4730/html5/thumbnails/8.jpg)
8
![Page 9: Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for bathymetric processing Ben R. Hodges Dept. of Civil,](https://reader038.fdocuments.us/reader038/viewer/2022102805/5517e63f550346c1568b4730/html5/thumbnails/9.jpg)
9
![Page 10: Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for bathymetric processing Ben R. Hodges Dept. of Civil,](https://reader038.fdocuments.us/reader038/viewer/2022102805/5517e63f550346c1568b4730/html5/thumbnails/10.jpg)
10
![Page 11: Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for bathymetric processing Ben R. Hodges Dept. of Civil,](https://reader038.fdocuments.us/reader038/viewer/2022102805/5517e63f550346c1568b4730/html5/thumbnails/11.jpg)
11
![Page 12: Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for bathymetric processing Ben R. Hodges Dept. of Civil,](https://reader038.fdocuments.us/reader038/viewer/2022102805/5517e63f550346c1568b4730/html5/thumbnails/12.jpg)
12
![Page 13: Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for bathymetric processing Ben R. Hodges Dept. of Civil,](https://reader038.fdocuments.us/reader038/viewer/2022102805/5517e63f550346c1568b4730/html5/thumbnails/13.jpg)
13
![Page 14: Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for bathymetric processing Ben R. Hodges Dept. of Civil,](https://reader038.fdocuments.us/reader038/viewer/2022102805/5517e63f550346c1568b4730/html5/thumbnails/14.jpg)
14
![Page 15: Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for bathymetric processing Ben R. Hodges Dept. of Civil,](https://reader038.fdocuments.us/reader038/viewer/2022102805/5517e63f550346c1568b4730/html5/thumbnails/15.jpg)
15
![Page 16: Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for bathymetric processing Ben R. Hodges Dept. of Civil,](https://reader038.fdocuments.us/reader038/viewer/2022102805/5517e63f550346c1568b4730/html5/thumbnails/16.jpg)
16
![Page 17: Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for bathymetric processing Ben R. Hodges Dept. of Civil,](https://reader038.fdocuments.us/reader038/viewer/2022102805/5517e63f550346c1568b4730/html5/thumbnails/17.jpg)
Summary of Cell-Edge technique
• Use median filter on fine grid data with Matlab medfilt2() function for baseline coarse grid.
• Identify coarse grid cells with a large fraction (45%) of subgrid cells that are a defined increment (0.2 m) higher than coarse grid median and use 75th percentile for coarse grid elevation.
• In each coarse grid cell, begin at median elevation and sweep upwards in elevation increments (0.1 m) using Matlab bwboundaries() function to identify obstacles.
• Find highest obstacle that crosses entire cell on X axis, and create an edge feature in X direction.
• Repeat for Y direction.
17
![Page 18: Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for bathymetric processing Ben R. Hodges Dept. of Civil,](https://reader038.fdocuments.us/reader038/viewer/2022102805/5517e63f550346c1568b4730/html5/thumbnails/18.jpg)
Conclusions• Image processing techniques (available in Matlab) provide
powerful tools for bathymetric processing.• Advantage of Cell-Edge method: Creates a coarse grid array
with cells and edges that create hydraulically blocking features.
• Open issue: How to confirm that the edges are continuous?• Open issue: 75th percentile elevations on high cells tend to
slightly underestimate blocking elevation.• Open issue: How to handle connectivity of subgrid channels?• Disadvantage: Median filter is computationally expensive for
large arrays.
18
![Page 19: Hydrodynamic modeling for river delta salt marshes using lidar topography A Cell-Edge technique for bathymetric processing Ben R. Hodges Dept. of Civil,](https://reader038.fdocuments.us/reader038/viewer/2022102805/5517e63f550346c1568b4730/html5/thumbnails/19.jpg)
Acknowledgements• Coastal Bend Bays and Estuaries Program• U.S. National Science Foundation• Texas Water Development Board• City of Corpus Christi• U.S. Army Corps of Engineers
19