River Simulations II
October 2008


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The constrained river simulation can also be overlayed on a map or satellite mosaic:


(Click for larger image)

Here are the 100 year results of a simulation using a fixed-width of 400 m:


(Click for larger image)

Here are the 100 year results of a variable-width simulation:


(Click for larger image)

Different combinations of the various simulation parameters (e.g. width, depth, flow, bottom composition, integration distances, etc...) can yield an enormous variation in river shape. Some of the configurations are quite 'wild':


I can also plot, using colors from red to green to blue, how long the river stays in any one place as it moves across the valley during 100 years:

For this study, however, I am interested in more realistic simulations that are fairly 'tame':


These simulated rivers don't necessarily travel very far during 100 years, depending on their erosion rates:

I can also plot how much surface area and sediment the river erodes from the valley, and where:

Simulations also accumulate statistics about the river length, its sinuosity ('curviness') at different scales, and cumulative coverage area and total erosion:

Everything considered, I am looking for simulations that resemble the river as it was 100 years ago, before human intervention and management began to change and constrain its shape:


(Click for larger image)

The 'simple' models I am using cannot generate the specific detail which is unique to this river (including multiple channels, 'braiding', chutes, islands, and sand bars), but by performing a large number (3000+) of simulations using slightly different input parameters, I can generate a diversity of river shapes and dynamics that, all together, approximate what I think the river might do during the next 100 years:

I can then accumulate the results from all simulations into a database in order to sort and search the data to extract specific examples of river behavior (such as the greatest and least lengths or erosion rates), or to draw conclusions from trends in the behavior (e.g. relationships between 2 or more variables such as erosion and length):

Reading: runs.rsq...
1064 entries read
Sorted by maximum erate - top 5 entries:
           erate           length                           file         avwidth0            depth             diam             flow            sdist           erate0          avwidth            cArea            eArea
---------------- ---------------- ------------------------------ ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ----------------
       10.922526    245477.926265             iMac/test0143.mnrr       433.661987         2.750000         0.001250      1400.000000         1.250000         3.599963       424.173739       795.000000    163167.446220
        8.472486    191130.990917             iMac/test0134.mnrr       433.661987         2.750000         0.001250      1200.000000         1.250000         3.600004       417.767380       601.750000    100806.430656
        7.848543    215845.829969             iMac/test0137.mnrr       433.661987         2.750000         0.001250      1400.000000         0.750000         3.599998       419.904026       643.250000     89514.967841
        7.526362    191231.410205             iMac/test0287.mnrr       433.661987         3.000000         0.001250      1400.000000         1.250000         3.599978       438.686099       566.750000     90986.196976
        7.320121    208266.307233             iMac/test0140.mnrr       433.661987         2.750000         0.001250      1400.000000         1.000000         3.600050       421.976723       666.250000     90319.841395
Sorted by maximum erate - bottom 5 entries:
           erate           length                           file         avwidth0            depth             diam             flow            sdist           erate0          avwidth            cArea            eArea
---------------- ---------------- ------------------------------ ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ---------------- ----------------
        0.804644    159230.555238             iMac/test0291.mnrr       433.661987         3.250000         0.000500       800.000000         1.000000         1.200000       439.570373       222.500000     12247.120470
        0.798773    151794.928451             iMac/test0435.mnrr       433.661987         3.500000         0.000500       800.000000         1.000000         1.200000       439.896821       219.000000     11878.577970
        0.798249    146177.679480             iMac/test0441.mnrr       433.661987         3.500000         0.000500      1000.000000         0.750000         1.200000       437.219222       205.750000     10610.426920
        0.770893    149729.319793             iMac/test0288.mnrr       433.661987         3.250000         0.000500       800.000000         0.750000         1.200000       438.551614       208.250000     10789.492193
        0.717024    148776.993226             iMac/test0432.mnrr       433.661987         3.500000         0.000500       800.000000         0.750000         1.200000       439.055634       204.500000     10465.896728

Loading from runs.rsq
2615 entries read
Sorted by total length - 2615 entries:
    i      totalLength           length            cArea            eArea            erate                           file         avwidth0            depth             diam             flow            sdist           erate0
----- ---------------- ---------------- ---------------- ---------------- ---------------- ------------------------------ ---------------- ---------------- ---------------- ---------------- ---------------- ----------------
    1    776135.792425    245477.926265       795.000000    163167.446220        10.922526             iMac/test0143.mnrr       433.661987         2.750000         0.001250      1400.000000         1.250000         3.599963
    2    662674.920443    236444.152114       562.000000     87620.147731         5.390537             iMac/test0404.mnrr       433.661987         3.250000         0.001250       800.000000         1.250000         3.600008
    3    649278.177699    194657.363285       562.250000     95463.515039         6.548363             iMac/test0116.mnrr       433.661987         2.750000         0.001250       800.000000         1.250000         3.600012
    4    637204.392931    224838.845225       553.750000     88507.424776         6.000637             iMac/test0260.mnrr       433.661987         3.000000         0.001250       800.000000         1.250000         3.599987
    5    575770.123505    223716.055261       607.750000     92588.754283         6.692613             iMac/test0269.mnrr       433.661987         3.000000         0.001250      1000.000000         1.250000         3.600025
    6    562917.536209    200232.526957       518.500000     79182.722680         5.512574             iMac/test0080.mnrr       433.661987         2.750000         0.001000       800.000000         1.250000         3.599996
    7    562072.148419    210579.351213       566.000000     81699.705390         5.661451             iMac/test0692.mnrr       494.557565         2.750000         0.001250       800.000000         1.250000         3.600015
    8    557355.215112    235817.205567       571.500000     82177.456456         6.000770             iMac/test0413.mnrr       433.661987         3.250000         0.001250      1000.000000         1.250000         3.599998
    9    542722.996488    177337.773194       494.000000     72671.936247         5.353781             iMac/test0224.mnrr       433.661987         3.000000         0.001000       800.000000         1.250000         3.599996
   10    537046.222635    183716.166324       471.750000     69006.385026         4.722043             iMac/test0548.mnrr       433.661987         3.500000         0.001250       800.000000         1.250000         3.600011
...

r = 0.334147, r = 0.485051, r = 0.453311

r = 0.921904, r = 0.922270, r = 0.963438

The aggregate results, although completely deterministic in nature, can provide a probabilistic interpretation of what the actual river might do, and where it might go, during 100 years:


Continued on next page


©Sky Coyote 2008