The Sun.
London, England, 1858-04-05 00:00:00

THE NAVIGATION OF THE DANUBE.

(From the Times Correspondent.)
CONSTANTINOPLE, MeetcH 16.
Long before the last war, indeed ever since the
Russian occupation of the mouth of the Danube,
complaints reached Europe about the daily dete-
riorating state of the navigation, which was attri-
hutable°to the negligence, or rather policy, of this
Power. It was remembered that while the Turks
were in possession of the outlets of the river a uni-
form depth of 14 feet was maintained over the bar
at Salina, which had become the main, if not the
only channel, frequented by vessels of commerce
- since the beginning of this century, when the St.
- George's branch, formerly used, underwent a great
deterioration. In the time of the Turks every
vessel going out of the river was obliged to take a
rake in tow over the bar. This contrivance and
occasional dredging produced the desired result.
The Russians kept two dredging machines, but
they were almost always out of order ; while the
obligation for vessels going out to take a rake over
the bar fell altogether into disuse. No wonder that
the blame of the accumulation of sands over the
bar was thrown upon them.
Recent surveys and the examination of the whole
question by Captain Spratt and the engineers
. attached to the commission have shown that, if the
Russians were perhaps not altogether guiltless, the
deterioration was a steady, inevitable result of the
- action of the winds and waters, over which neither
- Muscovite power nor however great we
might suppose both, had any control. It is the
steady advance of a river delta in a tideless sea
which has to be dealt with at the mouths of the
Danube—that is, one of the most difficult questions
of hydraulic engineering, which has never yet been
satisfactorily solved.
As the object of the commission is to effect a last-
.
. ing improvement, it was above all necessary to
understand thoroughly the local conditions of this
advance, in order to work with, instead of against,
these causes ; to choose the channel which is least
exposed to these deteriorating influences ; to help
the river in discharging the large quantity of so-
luble mud which it brings down with it to the sea,
and thus keep a channel open.
The fullest explanations on this subject have
been given to the commission by Captain Spratt,
RN., who in 1856-57 spent the greatest part of
the summer and autumn on the coast, and in the
different branches of the river. As the subject is
one of great public interest for England, as well as
Europe in general, I will give you the main results
of his observations.
The movement of matter along this as every other
coast is the result of the seas and currents, accord-
ing as one or the other of these influences is pre-
vailing. On a coast exposed to an open sea of wide
extent the prevailing winds and the waves caner d
by them have naturally the greater effect. The best
proof of this on the Danube coast is found by the
great changes which take place at the bars after
every strong gale. The prevailing winds on the
west coast of the Black Sea are from the north and
north-east. Easterly gales oceur less frequently,
and south-east are even rarer. The greatest wave
will therefore come from Odessa and Kieburn, 150
miles off, and strike on the lower part of the Kilia
delta and on Sulina. The question now arises, how
will this wave movement affect the formation of the
banks? Neither branch of the river brings down
coarse material, only fine sand and mud. The con-
sequence is that at the mouths, and on either side
at a short distance, the banks are composed of river
sand and mud, combined with river and sea shells,
but at a mile or two from either month, and along
the whole coast from Dniester to Kustendje, the
banks are white sand and broken shells, the sand
being derived from pounded fragments of the vast
bed of sea shells that are annually produced on the
shallow bottom of this coast, and cast on shore by
every gale. The prevailing north and north-east
gales, striking in full force the lower part of the
Kilia delta, tend to carry a large portion of the mud
and sand brought by the southern mouths of it
down to Sulina, and, indeed, on examination, it
has beenfouud that nowhere on the whole delta have
the shallows increased so rapidly as between the
Kilia and Sulina. The Russian surveys of 1830,
compared with those made last year, show au in-
crease of 11 mile in the direction of Sulina.
While the sand brought down by the lower
mouths of the Kilia thus fills up gradually this
b-sin, the coarser matter, being thrown on the
Suliva beach, tends to consolidate it, and the dry
edges becoming more rapidly formed, they keep
the smaller stream within its limits, and obtain a
better scour. This accounts for the bar at the
- Sulina being in a better state than any of the other
branches.
But, as the prevalent winds are diagonal to the
coast, the coarse matter has a tendency to be moved
from the shallows in its vicinity to the south-west,
and, on inspection of the chart, this is found two
miles below Sulina, where a succession of high sand-
bills extend till within a shot t distance from the St.
George's mouth. This is likewise the explanation of
the greater proMinence of that part of the coast.
Prom these observations the inference must be
drawn that the delta makes the greatest advances
wherever it is most fully exposed to the action of
the wave movement, which is from the four
southern mouths of the Kilia down beyond the
If any additional proof was required for showing
which way the delta is forming, it would be found
in the soundings. All along the part of the coast ex-
posed to this great wave movement the 20 fathom
line is at 15 to 20 miles from the shore, while
north and south of it it is at 3to 4 miles. Any
works, therefore, made within that rayon would be
soon absorbed by the gradual advance of the shal-
lows. The southern mouths of the Kilia, which
are in that rayon, are so deteriorated already that
they are out of the question ; but, as the Sulina is
likewise exposed to the same influences, it must
share sooner or later the same fate.
Neither the northern or Ochakoff mouth of the
Kilia branch nor the St. George's mouth is so much
exposed to these external deteriorating influences.
At the St. George's the coast has scarcely ad•
vauced since the Russian surveys in 1830, and only
a small portion of the drifts of Sulina and
Kilia reach it, and that mainly by shore surf ; but a
large portion is blown on its northern beach in high
sandhdls, so that soundings show at St. George's,
as well as to the north of it, 20 fathoms in 3 to 4
miles. This shows that the St. George's increases
mainly by its own deposits.
The Ochakoff, which is the northernmost
mouth, except the insignificant Belgorod, falls in
beyond the northern margin of tee wave move-
. ment, which is deprived of a part of its originating
force by the projection of the land about Cape
Bolaban before it reaches this mouth. The wave
thus intercepted expands, and strikes, accsrding to
a well-known law, with diminished force laterally.
The proof of this is found in the fact that north-
east gales always bring an east-north-east swell
at Ochakoff. No shore movement of any force,
therefore, takes place at this mouth by the
prevalent north-east gales. This is damaging to
the Ochakoff mouth as a natural condition,
as the deposits brought down by the river
settle down about it, but it is in favour of its
artificial improvement in consequence of the slow
advance and the smaller cost to keep pace with.
Besides this the works would be less exposed to
the action of the waves, consequently more econo-
mical. These reasons have induced Captain Spratr,
to pronounce for th© Kilia. The Commissioners
themselves are divided between the two other
- branches of the river. France, Russia, and Prussia
advocate the Sulina, England, Austria, and Sar-
dinia the St. George's branch. The Turk has not
pronounced yet.
Etch party has given in its plans,—Mr. Hartley,
the chief engineer of the Commission, and Mr.
Wer, an Austrian engineer, advocating the St.
- George's, and Mr. Nobiling, chief engineer of the
hydrotechnic waters on the Rhine, in favour of the
Sulina. The difference between them lies in the
money question. The whole Commission is agreed
that the St. George's branch is the beat channel,
but those who advocate the S ulina do so because
they fear that the works at the St. George's being
on the largest river will be too expensive, and con-
sequently oppress the navigation which is to pay
the interest of the outlay.
Two systems are advocated for removing the bars
at the Danube's mouth ; first, by dredging and
raking ; secondly, by running out piers to contract
the river's current. The first of these methods is
strongly advocated by long residents in the country
and by some engineers as a cheap and efficacious
mede of obtaining a greater depth. The members
of the Commission and their engineers reject it
unanimously as an adequate mode of removing the
obstacles at the mouth of the Danube. The Com-
mission gave a trial to the dredging and raking
system last summer, but the result was not satis-
factory ; two months' work did not show a gain of
more than six inches, and this during the most
favourable time, when the current was strongest,
consequently best able to carry away the mud and
sand stirred up by the rake or dredge. The rake
• made from sixty to eighty trips a-day over
the bar, as much as might have been made, in
a month during the old Turkish regime. If
it answered then, it was, according to the opinion
of the Commissioners, from the different formation
of the shoal at the mouth. The sea bottom at pre-
sent before Sulina has a slope seawards of 1-100.
In 1829 it was as great as 1-30 in the 20-30 feet
soundings ; all this has since filled up. Another
evil of the raking system is that it must cease
just during the time that it would be most
required—that is, during bad weather ; it is ;then
that the bar receives a fresh accession of matter