Thibodaux minerva. [volume] (Thibodaux, La.) 18??-1858, 1853-08-13
Survey of the Bayou Lafourche.

GAYoso PLANTATION, August 9, 1858.
Mr. Editor: find in the journal of the proceedings of the
last Legislature report of the Senate standing committee
on leyees drainage &c., from which have extracted the
following report Of survey Of portion of the Bayou La
fourche by Professor Forshey and ask for insertion in
your paper believing that will be read with much interest
by your readers Prompted by the deep interest
which in with Others have in the subject Of the
improvement Of the Bayou Lafourche, have expressed
myself freely and only trust that investigation may
start up which will have for its object system, which
from the vast importance of the object be attained will
insure its execution. JOSEPH s. WILLIAMS.
REPORT ON RA YOU LAFoURcHE
SECTION lar DosALDsoNvnLE, 50 miles above New
OrleansHgh water width 226 feet taken 500 feet down
the bayou extreme rise and fall of river, 251 sectional
at high WATER 1851 So feet high water DEPTH
1916 feet height Of levee foot above water mark feet
SECTION II-Ar PAINcouRrv1LE, 70 miles down.-Hgh
rse and secona @eah
low do 200; heights levee foot above water mark, 40
SECTION HAT TmBoDAux "a miles down: High
water width at ferry landing 2275 feet low d. $780, rise
high water DEPTH 1885, height Of levee foot above high
water, SIS.
SECTION IvAr LoNGvLLE, Locks Of Baraaria Canal,
rise and fall, ISL; mean high water depth, 1905 high
water sectional area, 1857 low d. 752 mean height OF
levee from Thibodaux to Longvile, 6.5
Total length Of Bayou Lafourche-1o5 miles,
1t viii be perceived by careful inspection meas
urements at the Lafourche is in state OF nature, very
different stream from what improvements have made it, LIS
waters did not discharge themselves in rghtned plane
from the the Gulf escaping easily from its
banks Is miles above its mouths it found the level OF
low swamp (nearly the Gulf leve) making this in high
water its practical debouchure The rghtned plane OF
discharge hen from its source to point about ID to 80
miles down. 80 4ak
When levees applied to its banks and confined
waters within channel Of remarkably uniform width it IS
obvious that there must be great OF veo-
city, the smaller depth would enable the waters
to discharge without inundating the country.
Both these effects followed. The currents much
rapidly at Longve than Donalsonvie, that the
waters introduced in section of 1887 square feet vented
through channel Of 1857 feet But the whole effect not
creased by raising the evees higher the height Of
the evees here IS miles down the Lfourche is feet
inches greater than at that the
surface place of discharge has been elevated.
And this elevation will only subside when the increased
velocity shall have had time to enlarge by abrasion of the
bottom the capacity of the channel its proper demands
This depression should be Just feet ana after this should
be effected there could be further reduction the evees
continued to the mouth of the bayou because the right
lined plane of surface would be reached.*
The Instructions in the lower channel Of the Lauche
such render probable that this abrasion and depres
sion could not rapidly But these distractions removed
there might be increase Of capacity in the channel due to
the of velocity and until the evees extended
much further than at present down that stream, the de-
preston might be carried below the right line plant.
from the source of the bayou to the Gulf.
For these reasons it is very urged that force be
applied to the clearing out all logs RATS and bars in the La
fourche below Lockpor Unless this be done early ser
ousy fear another consequence The declivy in the first
few miles much greater than further down. and the velocity
acquired in steep plane, must carry down sedimentary
matters which they cannot transport rate due gutter
plane The consequence must be filling up of the lower
channels These serious considerations and deserve
early attention.
would also recommend further contraction Of the
OF the bayou at Donaldsonve such degree that the
capacity shall not be great that which enjoys further
ZN1aa thoh dpplyi fv 10 fin
inches per mile whereas, from Thbodaux to Longvle
~ miles, only about 8 of an inch per mile This will
account for the rising Of the water in the lower portions
the bayou.
We find here occurring in the Lafourche bayou precisely
what is taking place in the Pc and all European rivers that
are levied and have broken planes Of discharge filling up
in the channels of gentler declive by sediments brought
down by the velocties Of sleeper plains.
closure Of the mouth Of this bayou at Donadsonve by
onethrd OF its whole capacity 1858 feet should have
about 700 feet adutage and the channel could discharge
this all the way through without danger Of nundaton The
would not be apprecaby affected by this contraction Of 150
square feet and would strongly urge its being done al
the inhabitants of its banks would consent there bt
but little doubt Of the best policy. a0od be to close tn
bayou at its source. culver could be managed
supply aack-curent navigation and the labor expense
and danger Of line of 100 miles Of high levee could b.
avoided 1t is very doubtful if the difference between hgf
what will cost, after the completion Of railroad to New
| Orleans.
This suggestion thrown out for the population interested
| The river would not sensibly show the difference.
Respectfully submitted, c. G. FoRsHEY, G. e.
river along the Canal de la Companie to the Laourche
/ IDngvile