Channel Map
Channel Cross-Sections
Channel Maintenance
Friction Factors Within Levees
The following pages show the site plan
dimensions for the original construction of the channel. It is the same size as the
original channel. Also shown are computations of flow area for 12 cross-sections of the
river: four cross-sections above the straightened channel in the original river, four
cross sections in the straightened river channel and four cross-sections in the original
river channel below the levee system. These cross-sections, taken from the HEC-2 computer
model, show that the straightened river channel is of similar size to the original river
channel. Also, shown is a map made of the straightened river channel in 1984, five years
after the 1979 flood and one year after the 1983 flood. This map shows the straightened
channel to be of similar size to the original river channel. From this map it can be seen
that the amount of sand moving down the river channel occludes the channel to a size
controlled by the energy in the nominal flow of the river and that no matter how large the
channel is constructed, it will be restricted by natural sand levees to a width of 250
feet at brink height. Information shown on the map indicates that this will happen within
five years time.

The cutoff channel in this
1965 U. S. Army Corp of Engineers sight plan is 150 feet wide at the base and
approximately 250 feet wide at the top. This is approximately the same size as the winding
river channel that it replaced. This 1965 site plan also shows the ponding reserve for the
fairground area. Construction in this area, 10 feet lower than the fairground property has
now been developed. This has necessitated pumping to maintain reserve during the spring
flood months.
HEC-2 CHANNEL
CROSS-SECTION
|
RM286.533
|
water @
|
274.5
|
|
|
|
|
|
|
|
|
|
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249.5
|
248.8
|
231
|
235
|
236
|
249
|
|
|
|
|
|
|
|
|
100160
|
100195
|
100250
|
100300
|
100380
|
100430
|
|
|
|
|
WIDTH=
|
270
|
|
|
887.25
|
1903
|
2075
|
3120
|
1600
|
|
|
|
|
AREA=
|
9585
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
RM286.927
|
water @
|
275.7
|
|
|
|
|
|
|
|
|
|
|
253
|
233
|
230.5
|
235.3
|
250
|
|
|
|
|
|
|
|
|
|
100490
|
100530
|
100600
|
100650
|
100720
|
|
|
|
|
|
WIDTH=
|
230
|
|
|
1308
|
3076.5
|
2140
|
2313.5
|
|
|
|
|
|
AREA=
|
8838
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
RM287.33
|
water @
|
276.2
|
|
|
|
|
|
|
|
|
|
|
255
|
240.5
|
235
|
236
|
253
|
|
|
|
|
|
|
|
|
|
101665
|
101785
|
101860
|
101935
|
101970
|
|
|
|
|
|
WIDTH=
|
305
|
|
|
3414
|
2883.75
|
3052.5
|
1109.5
|
|
|
|
|
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AREA=
|
10460
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
RM287.508
|
water @
|
277.2
|
|
|
|
|
|
|
|
|
|
|
250.4
|
236.7
|
232.4
|
235
|
246
|
250.7
|
|
|
|
|
|
|
|
|
102220
|
102258
|
102300
|
102355
|
102395
|
102432
|
|
|
|
|
WIDTH=
|
212
|
|
|
1278.7
|
1791.3
|
2392.5
|
1468
|
1067.45
|
|
|
|
|
AREA=
|
7998
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
RM287.82
|
water @
|
277.3
|
|
|
|
|
|
|
|
|
|
|
250
|
233
|
250
|
|
|
|
|
|
|
|
|
|
|
|
101000
|
101200
|
101300
|
|
|
|
|
|
|
|
WIDTH=
|
300
|
|
|
7160
|
3580
|
|
|
|
|
|
|
|
AREA=
|
10740
|
CHANNEL
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
RM288.171
|
water @
|
277.8
|
|
|
|
|
|
|
|
|
|
|
258.7
|
241
|
234
|
229.7
|
233
|
232
|
234.8
|
250.7
|
|
|
|
|
|
|
100805
|
100842
|
100850
|
100870
|
100930
|
100950
|
101000
|
101033
|
|
|
WIDTH=
|
228
|
|
|
1034.15
|
322.4
|
919
|
2787
|
906
|
2220
|
1156.65
|
|
|
AREA=
|
9345
|
CHANNEL
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
RM288.99
|
water @
|
278.6
|
|
|
|
|
|
|
|
|
|
|
253.6
|
241
|
238.8
|
239
|
252.7
|
|
|
|
|
|
|
|
|
|
100775
|
100790
|
100800
|
101005
|
101033
|
|
|
|
|
|
WIDTH=
|
258
|
|
|
469.5
|
387
|
8138.5
|
917
|
|
|
|
|
|
AREA=
|
9912
|
CHANNEL
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
RM289.46
|
water @
|
279.2
|
|
|
|
|
|
|
|
|
|
|
252.5
|
240.7
|
240
|
241.5
|
240.8
|
241.8
|
252.6
|
|
|
|
|
|
|
|
101815
|
101892
|
101945
|
102008
|
102028
|
102070
|
102080
|
|
|
|
WIDTH=
|
265
|
|
|
2510.2
|
2059.05
|
2422.35
|
761
|
1591.8
|
320
|
|
|
|
AREA=
|
9664
|
CHANNEL
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
RM290.08
|
water @
|
279.7
|
|
|
|
|
|
|
|
|
|
|
271
|
244
|
242
|
243.8
|
240.5
|
244
|
250.8
|
251.6
|
|
|
|
|
|
|
102730
|
102805
|
102840
|
102940
|
103040
|
103112
|
103130
|
103140
|
|
|
WIDTH=
|
410
|
|
|
1665
|
1284.5
|
3680
|
3755
|
2696.4
|
581.4
|
285
|
|
|
AREA=
|
13947
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
RM290.46
|
water @
|
280
|
|
|
|
|
|
|
|
|
|
|
263.8
|
259.2
|
241.4
|
237.4
|
238.8
|
238.4
|
244.4
|
248
|
248.2
|
257
|
|
|
|
|
102447
|
102478
|
102526
|
102563
|
102610
|
102655
|
102665
|
102682
|
102700
|
102732
|
WIDTH=
|
285
|
|
|
573.5
|
1425.6
|
1502.2
|
1969.3
|
1863
|
386
|
574.6
|
574.2
|
876.8
|
AREA=
|
9745
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
RM291.81
|
water @
|
280.8
|
|
|
|
|
|
|
|
|
|
|
266
|
244
|
240
|
|
|
|
|
|
|
|
|
|
|
|
17200
|
17300
|
17400
|
|
|
|
|
|
|
|
WIDTH=
|
200
|
|
|
2580
|
3880
|
|
|
|
|
|
|
|
AREA=
|
6460
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
RM292.34
|
water @
|
280.9
|
|
|
|
|
|
|
|
|
|
|
244
|
240
|
|
|
|
|
|
|
|
|
|
|
|
|
14650
|
15000
|
|
|
|
|
|
|
|
|
WIDTH=
|
350
|
|
|
13615
|
|
|
|
|
|
|
|
|
AREA=
|
13615
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
AREA
|
|
WIDTH
|
|
|
|
|
AVERAGE OF 4 X-SECTIONS SOUTH OF CHANNEL IS
|
9220
|
|
254
|
|
|
|
|
AVERAGE OF 4 X-SECTIONS IN CHANNEL IS
|
9915
|
|
263
|
|
|
|
|
AVERAGE OF 4 X-SECTIONS NORTH OF CHANNEL IS
|
10942
|
|
311
|
|
|
|


When the 1979 flood occurred, 90% of the cutoff channel had become
restricted to a width at brink height of 250 feet and trees had grown to the bank of the
remaining channel.

One half mile of the cutoff channel had been used
to dredge 800,000 yards of sand. This operation ended in November, 1978 (prior to the 1979
flood) the sand dredging operation opened up the cutoff channel to a width of 500 feet and
deepened it an additional 10 feet in places.

Five years after the dredging operation ended,
sand moving down the river channel had refilled much of the dredged area and natural sand
levees had formed (see map previous page) again restricting the cutoff channel to a width
of 250 feet.

This section of river can be observed today by
looking north of the I-55 highway bridge. The dredged area has completely refilled with
sand and trees over 10 years old have grown over the entire dredged area except for the
250 foot wide restricted cutoff channel.

|