The daily dispatch. [volume] (Richmond [Va.]) 1850-1884, 1878-03-11


MARCH IL 1873.
/ Lower end OF Dutch Gap cutoff, 1915
feet : Water-mark by Mr.. Allen. -.1ss
Yarina wharf, 0.6A feet !; Water-mark; by
Mr.. Aiken. & !;s ,Is.;s..,i y,. :
City Point, 2.2o feet; water-mark by hr.
Cook. - .,,,, ..
Westoverr3 wharf, 1.s2 ieet; u vwater-mark
on shore. - 80, 8. :. ~, - ],
The height Of this flood ut Rockets was
II feet above the arrow on the monument
marking. the height OF the flood OF 1870.
The latter is stated TO have been "a feet
inches above high tide, ], BY the recent
measurement this arrow is % feet 7s inches
above present mean high tide-a difference
Of Al inches. In 1870 The height OF high
tide Was not as accurately known as 1t Is
now, from continuous observations since
that time; but it is not unreasonable to ex-
pect an increase In the height of high tide
from the deepening of the channel. The
current having less assistance flows with
greater velocity, and meeting an impossible
barrier in the falls may pile up higher.
This discrepancy is mentioned in order to
prevent misunderstanding in the future.
The food was Clio feet higher at Belle
Isle than that OF 1870, and at the water
works and several other points above the
height was about Il feet above that OF 1870.
This should be sufficient proof, il any is
needed, that the wing-dams below Rich
mond did not add sensibly to the height Of
the water. Through the courtesy OF Mr..
Robert Gordon, civil engineer in the en-
ployment Of the Richmond and Danville
Railroad Company, ] have, says Mr.. Whit
comb, the height of the food at several
points covering four miles above the Rich
mond and Danyille railroad bridge. In this
distance the stope Of the surface appears to
have averaged Is 52-100 feet per mile.
THE HIGHEST FLOOD OF WHICH THERE IS A
RECORD.
This was the highest flood in this part of
the river Of which we have an accurate
record; for it is incredible that the monu-
meDt at Turkey island, thirty miles below
Richmond, marks the height OF the flood Of
It'll. 1t is reported to be about forty-five
feet above tide, while the recent flood was
probably not over seven feet at that place.
I have recently learned that the flood OF
It'll at Bremo Bluff, siXtY-seven miles d6oUe
Richmond, was Just about the height Of that
Of 1870. In the recent flood the height was
two feet less at Bremo Bluff, but at Maid
ems Adventure was several inches higher
than in 1870.
The effect of this and preceding freshets
on the channel is then stated at length by
the Engineer. The entrance to the ship
lock and the channel in front OF the Old
Dominion Steamship Company was reduced
in depth. From this point to the lower
end of Drury's island there was no appre-
ciable change in the channel. Opposite the
lower end of Drury's island, for about 400
feet, the dredged channel was shoaed so
that for short distance there were but 14s
feet depth. The apparent cause for this is
that the flood poured great volume OF
water over the dikes at the head OF the island,
and also over the low-grounds opposite and
to the east OF this point; and similar effect
may he produced at any succeeding similar
flood, unless leyees are constructed at these
points, which will more completely contne
the water to the channel. On the upper
part Of Richmond bar the partially y-dredged
channel was filled, but on the crest the river
bed was rounded out, giving better chan
mel than before.
OTHER EFFECTS OF THE FLOOD.
The lower part OF the bar was considerably
secured, and has Is feet depth for so feet
width, and sixteen for l60 feet width. There
was a scour Of 1S feet on Randolph's flats,
but not in the direct channel. The direct
channel, which had been recently dredged,
was filled, leaving, however, 155 feet depth
for navigation. Below this to the end Of the
shoal there was great scour, and on the
lower 800 feet there are from 1Ss to 20 feet
in depth for about 200 feet in width where
in 1874 there were but 133 feet, and as late
as 1876 but little over IA feet. For perhaps
1000 feet above and below the wing
dam on the crest OF Warwick bar we have
channel IS feet deep, and opposite the
dam. where we were dredging to get IL 1eet
in the middle Of November, there are 25 feet
depth for 120 feet width, and IS feet for 4
width Of $50 feet. The shoal in Kingsland's
reach was increased in length, and there
was one sounding on it in the usual track
OF vessels, showing only 133 feet. The
river is LOO feet wide here, 800 feet wider
than it is Immediately above and below,
but this was not the cause Of this increase
in the shoal. just above the river bends
suddenly to the left, and just below it again
bends as suddenly to the right. In the
November flood the river oycrflowed its
banks, and a great volume poured across
the elbow, reaching the river below in
about three-fifths OF the distance around.
The effect was to fill up the water lower
down, and to slacken the current in the
river between the points. Naturally de-
posit was made where the velocity was re-
duced. The remedy is to build levee to
prevent this waste, and then to regulate
the width Of the river.
In Trent,s Reach the channel was 10 feet.
AS this shoal is avoided by Dutch Gap cut
off, no effort has been made to deepen the
channel. The river below Dutch Gap has
not been examined since ireshet. The effect
OF freshets on the channel have been good.
They have widened and deepened it except
at few points, and the shoals left by the
November food were removed in twenty
five days work OF three dredges.
PRESENT CONDITION OF TUE CHANNEL.
The channel over Rockets reef remains
essentially as at the date OF the last annual
report. It's somewhat wider than then, but
IA feet Is all that can be carried to the
wharYes of the city at mean high tide. 1t
will REQUIRE SIX months work OF the ma
chinery to open a channel to 18 feet depth.
Below the reef the depth is generally 16 feet
and over; but the available depth-that is,
the depth for 4 minimum Width, say 30 feet
on Richmond bar and Randolph's flats-is
155 feet, the bottom being OF sand. In
spring tides they are usually inches more,
and in neap tides 5 inches less, than
this: and during high westerly winds the
depth at high-tide may be l. feet less than
these. There has been Il gain OF at least
one foot in depth of channel below Rock