I've created some contour plots of the final coverage and erosion, calculated areas covered by different fractions of all simulations, and tried to clean up the graphics a bit to make all elements easier to see. I don't know how this looks on your display (I have an Apple LCD), so let me know if you have problems seeing the results.
Here are just the contour limits for coverage by 95%, 75%, 50%, 25%, 5%, and 1% of all rivers:
Here are contours overlayed on the maps and satellite images. The minimum non-zero value of the blue area outside of the 1% line is 0.000326 (1 out of 3072 rivers, although not necessarily the same one everywhere). Note that several towns are outside of the 1/100 danger line, while Mission Hill is at 5/100, etc...:
Here are approximate areas between the contour lines at both the final 4x interpolation (125 x 125 m) and at the original accumulated coverage (500 x 500 m). The original area of the full-width digitized river (avwidth = 747.84 m, length = 95353.75 m) is around 71.31 km^2, although all the width-limited simulations start with less than this value:
--- 0.125 x 0.125 km ---
Loading from runs.rsq
3072 entries read
Area at x percent common coverage:
1.00 - 0.95: 139.59 139.59 km^2
0.95 - 0.75: 93.36 232.95 km^2
0.75 - 0.50: 86.22 319.17 km^2
0.50 - 0.25: 94.84 414.02 km^2
0.25 - 0.05: 157.00 571.02 km^2
0.05 - 0.01: 113.69 684.70 km^2
0.01 - 0.00: 200.73 885.44 km^2
Total coverage: 885.44 km^2
--- 0.5 x 0.5 km ---
Loading from runs.rsq
3072 entries read
Area at x percent common coverage:
1.00 - 0.95: 191.75 191.75 km^2
0.95 - 0.75: 59.75 251.50 km^2
0.75 - 0.50: 68.50 320.00 km^2
0.50 - 0.25: 94.00 414.00 km^2
0.25 - 0.05: 163.50 577.50 km^2
0.05 - 0.01: 130.00 707.50 km^2
0.01 - 0.00: 217.75 925.25 km^2
Total coverage: 925.25 km^2
Here are contours for the total eroded area (in ha per 0.25 km^2):

