Getting MNRR coordinates

This month I've moved ahead in the schedule to what was originally planned for June, as I thought it was time to get started working with the actual river data. During the past 2 weeks I've worked on creating map and image mosaics of the Missouri National Recreational River from Gavins Point Dam to Sioux City, Iowa, and on writing some simple GIS software to semi-automatically extract coordinates from the river banks and valley walls. These coordinates will be used, along with depth, flow, and bed/bank/sediment data, to initialize and update the meandering simulations which I will be running later this summer.

I've created one mosaic from 24 1957-1994 USGS 7.5' topographic maps at http://store.usgs.gov/. These maps had to be rasterized from PDF, rotated by from 1.1 to 1.65 degrees CW, overlaid, and aligned by hand in Photoshop. I think I did a reasonably good job. The small image below is at 6.25%, and the larger link is at 12.5% of the final actual size. This mosaic contains sufficient information for digitizing the river banks to better than 10 meter resolution, although I anticipate extracting coordinates only every 100-200 m:

(Click for larger image)

I've made another mosaic from Google Earth images at an 'altitude' of 20.17 km:

(Click for larger image)

I've adjusted the scale of the Google mosaic (x and y independently) so that it is about the same as the topo mosaic, and overlaid the two. I must admit that I did this after both mosaics were already assembled. Nevertheless, the correspondence at both the Gavins Point Dam end of the river and the Sioux City end are pretty good (and is virtually exact near the middle). To make it better, I really should go back and do them both again, adjusting the scale and offset of each satellite image as I add another topo map to make sure that corresponding features are properly aligned at all times. Nevertheless, I'm pretty happy with the results, and feel they will be sufficient for this project, at least initially.

6.25% and 12.5% mosaics:

(Click for larger image)

Close-up of Gavins Pt end:

Close-up of Sioux City end:

I've started writing a simple GIS program to allow me to digitize the river banks and valley walls from these mosaics. Here is an example of work in progress using the topo mosaic at 66.67% of full size:

(Click for larger image)

This program is pretty easy to use, and produces good results fairly quickly. Current program features include:

• A background image can be displayed as a guide.
  
  
• Points can be entered with the mouse on multiple curves.
  
  
• Points can be added, inserted, selected, moved (by mouse or keys), or deleted. Curves can be joined, split, or reversed.
  
  
• The current session can be saved to a file and restored so that digitization can continue at another time.
  
  
• All coordinates are in longitude and latitude decimal degrees. Coordinates reference landmarks (red stars in above, at least 2 required) which can be entered using known map positions.
  
  
• The display shows the lon/lat of the window center, and the scale (meters/pixel) at that point.
  
  
• Distances are calculated using oblate ellipsoid geometry, where:
  
  
  
  
  
  and a = equatorial radius, b = polar radius, phi = latitude, lambda = longitude. (See http://en.wikipedia.org/wiki/Earth_radius)
  
  
• The digitized paths can be viewed with or without the background image:
  
  
  (Click for larger image)
  
  
• Coordinates can be printed and used as input in meandering simulations:
  

  2 curves
  184 points
  41882.73 meters
  
  curve 1
  86 points
  20573.28 meters
    -97.481364767842    42.849775784354
    -97.479652972009    42.850024912405
    -97.477629940570    42.851519680710
    -97.475918144738    42.851644244735
    -97.472183317466    42.851145988634
  ...
    -97.271903205021    42.852516192913
    -97.268946466764    42.852391628888
    -97.266612199719    42.852391628888
    -97.264277932674    42.852765320964
    -97.262877372447    42.852889884990
  
  curve 2
  98 points
  21309.45 meters
    -97.482142856857    42.853139013040
    -97.479652972009    42.853512705117
    -97.476696233753    42.854010961218
    -97.473583877693    42.854010961218
    -97.472027699663    42.854010961218
  ...
    -97.269880173582    42.857000497828
    -97.267701524340    42.856626805752
    -97.265834110704    42.856626805752
    -97.264122314871    42.857000497828
    -97.262877372447    42.857374189904
  

Next to do are:

• Add multiple undo/redo for point addition, move, delete, etc...
  
  
• Add interpolation of paths using circular arcs to smooth and preserve curvature.
  
  
• Allow combining of multiple discrete sessions into a single mosaic.
  
  
• Use the program to digitize the MNRR and surrounding valley at ~100 m resolution.
  
  
• Calculate river centerline and width from banks.
  
  
• Add support to signify bank fortifications and other alterations to erosion rate.
  
  
• Add support for river depth, flow, bed composition, and other path-length-dependent attributes.