The Fargo forum and daily republican. [volume] (Fargo, N.D.) 1894-1957, 1911-02-09

sequently we have some bitches in
the state that have proved, not only
/ OF but small value to many of the land
| owners who were assessed for its
cost but a positive damage to others.
The factors entering into the proper
design of a drainage system are as
| follows: Rainfall, run-off, soil, drain
| age area, cross section, grade line and
| outlet. A study of the rainfall record
OF any locality in the United States
| will show that wet and dry seasons
| occur in cycles Of greater or less num-
| Der of years and also show that in
| some seasons there may fall in one
day or a part OF a day as much rain
| as in ordinary seasons would fall in
one or more months. 1t is this maxi
mum rainfall in a short period of time
that must be taken into consideration
| in determining the proper size of a
drainage channel; otherwise we may
see a stand of crops flooded and lost
in one season sufficient to pay for the
cost of constructing a ditch of the
right size. A fact worth noting here
| is that the maximum and monthly
rainfall during the growing season in
this valley is not far different from
| that in the northern portions of the
Mississippi and Ohio river valleys
when the annual rainfall is from two
! to three times as much as here.
Run Off.
BY un-off is meant that amount OF
| water which falls on a given drainage
basin which reaches the drainage
channel and flows away. The run off
varies greatly, depending on the char
acter OF the drainage basin, whether
the slope is fiat or steep, covered with
timber or grass, cultivated or bare
and whether the rainfall comes gently
or in violent storms. Obviously
drainage basin with steep slope will
give a greater amount OF un-off than
one with fiat slope; likewise bare
slope will give a greater amount than
ttmbered or grassed one, while
| cultivated one will give a small amount,
certain amount of the water being
taken up by the soil. A violent storm
will give a greater run-off than il the
same amount fell in a greater length
of time.
Soil.
There are many different kinds of
soil common to this state from which
y,
gravelly, loamy, gumbo, muck and hard
pan. Each one has different character
istics and each one requires different
treatment to bring them to the great
est degree of filth. Generally we speak
of the top layer of earth as the soil
and the underlying strata as sub-soil.
1t is not always easy to say where one
ends and the other begins while fire.
quently the line is clearly marked. It
is these soil characteristics that must
be taken into consideration in laying
out drainage system. Some of the
soils previously mentioned are capable
of being very retentive of water, while
in others the water flows quite freely
among among the particles. In soils
that are retentive of water 1t is quite
plain that we must plan our laterals
much closer together than in the open
sandy or gravelly soils.
Drainage Area.
In planning the main drainage cham
nels, it is most important that the en-
tire area that naturally falls toward
this channel or that may be brought
to it by laterals should be taken into
consideration, as we'll as the character
a..
that we may have this knowledge in
designing the proper size channel 1t
Is as great an engineering error to
design and construct a ditch or, any
structure too large with it's excessive
cost as 1t is to design it too small
Cross Section.
The cross section, as you all know.
refers to the depth and width. The We
locity Of the water flowing in an open
| ditch is retarded by contact with the
material of which the sides and bot
tom Of the ditch are composed. The
greatest velocity of water flowing in
an open channel is found in the deep
est part of the current just underneath
| the surface. The friction of water
Moving on water is much less than
| hoWing on the sides and bottom of the
| channel, hence it is better to make our
| dltches deep and narrow in preference
| to wide and shallow. as we get a
| greater velocity with the same grade
| line and we have a ditch that will be
more apt to keep itself free from OH
| struction and one in which it will be
more convenient to connect lateraIs.
| The ideal open ditch would be one with
perpendicular sides, since Won would
have less FRACTIONAL area, but this is
impossible except in solid rock excava-
tlon. Ordinary clay soil will stand
with a slope of one to one, while an
other soil may require a slope of one
and half to one.
Grade Line,
The total fall that a proposed ditch
may have from it's source to it's outlet
| is hxed by nature, and we must he
guided by this fall in determining
what the grade line shall be and must
make our cross section conform TO
this grade. 1t is desirable in a ditch
that we have velocity enough SO thai
1t viii keep itself free and clean and
yet not enough to make it scour badly.
Outlet.
1t is certain that we must have an
outlet, else our ditch would be value
less. This outlet must be large and
free from distractions and should al
| ways be into natural water course
Our streams in the Red river valley
nave banks that are higher than the
land one-fourth to one-half mile on
either side, and several instances are
known where outlets have been cut
through these banks with the result
That in times of nigh water The streams
have flowed through these artificial
outlets and DESTROYED large areas Of
crop, and the use of dam and flood
water gates required large expense
some skepticism concerning drainage
in the valley has arisen from the fact
that not enough Importance is given