Ottumwa semi-weekly courier. [volume] (Ottumwa, Iowa) 1899-1903, 1903-06-23

My Investigations began really
in 1890 when | made a meander sur
vey of the river on both sides, through
the city, from limit to limit; showing
the then existing bank lines as COM
pared with United, States surveys made
in 1S47. On May is, 10, 20, 81 and %.
1892, while the water was at its high
est stage, | plated the flood lines,
showing lands and lots which were sub
merged, for five miles on either side
of the river, throughout the city; also
noting currents, points of impact, cav
ing banks and tendencies generally.
During the past month have made
a new survey of the river from the
Market street bridge to point 5000
feet, above, meandering the right bank
thereof, and plating the came in con-
nection with the survey of 1890, points
liked by surveys made in 1875, also
1870, and the United States survey of
lS47. The map also shows top and
bottom of bank and location of bars.
This map also shows location of lots,
showing amount lost by erosion.
From my investigations find that
at every bend in the river in Wapello
county the transverse reaches have
moved down stream. 1t is well un-
derstood fact that this is true of all
streams flowing through alluvial de-
post; the reaches of these bends move
down at rate more or less rapid ac-
cording to the character of the banks
and none retrograde, whatever may be
the changes in the eourst of the river,
this gradual movement down stream of
the transverse reaches continues until
intercepted by natural features, such
as hills or rocks, or by artificial banks.
Il will digress here and speak of the
actions of rivers in general. In 1892
the writer meandered forty miles of
the Des Moines river and plated the
same in relation to the United States
survey made in 1S47. i found, which
presume is not new, but we'll known
law, that whenever the reaches ran.
parallel with the general course Of the
river there was little change Fat the
shore line by erosion; that whenever
the reaches ran transversely to the
general course nearly always on the
down stream side, be it either right or
left bank, the banks have changed by
erosion down stream, in some cases
|several hundred feet, but in no case
had an erosion taken place on the up
stream side; If there was such a move
ment it was trifling and, of short dura-
ton. found this to be true in mean
dering SIS miles of the Missouri river
in 1884, except that in that river com
plete evulsion was much more common
than in the Des Moines river This
does not hold good as to the Missis-
sippi in it's upper course.
THE great bend in question has
moved down stream at a point 400
feet above the Market street bridge,
$50 feet since the United States sur
yey was made. During the flood of
1892 the right bank moved southeast
erly and downstream about 200 feet,
at point at or near the sight of the
old ferry house.
1T will be seen that the same move
ment has occurred at.or west of the
c., NJ. & st. P. railway yards, one
mile above AS that reach flows
southerly the erosion is on the left
bank, that being on the down stream
side.
'The bed rock above the Market
street bridge forms the bed of the riv.
er on the northerly. side, but dips to
the southeast, and is some eight to ten
feet below the bed of the river at the
south end of the bridge.
II find that the territory submerged
during the flood of 1892 was 1000 feet
wide at the west city limits, 5000 feet
at the c., NJ. & ST.. P. railroad bridge
1000 feet wide at the southeast Of the
city limits, and only $500. feet wide as
| limited by nature at the Market street
bridge.
The extension of the Church street
grade reduces it to 1850 feet wide at
1 this point. from which deduct fifty feet
of piers and necessary ice breaks. II
may be readily seen that the same
amount of water must pass this point
that passes the other. and If the cross
section shows less capacity, can on,
| ~ do SO through an accelerated move
ment of the current. which, however
is aided by the rapids below the bridge
and which offsets the contraction oil
1.-THE channel to some extent. The point