The times dispatch. [volume] (Richmond, Va.) 1903-1914, 1912-07-28

Near MechnnicsviIe Turnpike. showing
indefinite channel.
cost OF the investigation. or about -
cents per acre.
Property lines as existing on the
ground arc in an unsatisfactory condi
tlCn. and TO show them on tho plan
with even n reasonable degree OF ac
curacy has involved considcra BILE work
NJ the several county lcgistries. In the
lower counties this work being hamp-
cred BY reason Of destruction 90 re-
cords during the war
On March Is. 1912. sri inches Of rain
ie!I IN hfteen hours and fifteen minutes.
causing the heaviest Hood within IN
knowledge of men who had !ivea for
,hirty years near tho Chickahominy
river. Practically the whole l9wland
IRON bluff to BLUM was submerged and
considerable damage especially to
roads and bridges. was cone. Crei.,h-
ton Road was preached. probably on
s'arch 49, in several places. one OF the
breaks being upward of nifty feet in
width and rendering the road ifnpass.
ablc for more than thrce weeks It's
1 cohaition on Marcn so. nfteen days af-
ter the storm. Is depicted In plaTc Ill.
iig ?. which shows Il break on the
lower bottom. but at !, considerable
could not be reached
Run-on.
During the latter put of Aurus,
isll' 81 inches OF rain foil in thirty
hours and forty-one minutes. bu. ex
tending over several days. The water
OF the Chickahominy River did no,
leave the banks. and was probably not
quite as high as is shown in plato l..
ne l. which picture was taken Apr'l
> 1912. or twenty-five Gays after the
storm OF March 10
The volume Of water yielded by a
drainage area through natural chan.
nels is termed the run-or.
Tho rate OF run-on is affected bv
many physical ana climatic conditions
such as the size. shape, slope and as.
rlcultural development Of the Drainage
area. the depth and character or inc
SOIL and the extent OF tho vegetation
upon IT, the duration. intensity and di
Tection OF storms. and the temperatnre
and evaporative capacity OF the atmos
phere.
Precipitation or rainfall is obviously
the most important OF these factors
but they are so comple< ana ,ntnr,
related that no formula for run-of ~.
deduced takes cognizance OF them an.
or is even moderately satisfactory
shed.
In the case of the chlekabom,ny
River. data are very neagre. Therc
Is probably but ono rain gage In tho
watershed. that at Ashland near ,h,.
extreme northerly headwatars There
arc no cages for recording heights
ana as far as known no measurement,
OF discharge have ever been made
During the progress OF the survey :,
was noted that a we'll defined chain of
nigh water marks extended througb
out the length OF the valley Thesr
marks showed as dark rings or bands
upon tho trunks OF many trees. and
the clean. healthy condition II the
mark above the bands indicated
that any higher stages OF the riyor
We're very infrequent and not long
sustained Levels were taken uoon
many Of these marks and they were
! subsequently, identified on tho accom- .
panyins profile as the ordinary winter
and spring high water stage OF tho
river.
In general 1t can he stated that land
drainage is most needed during the
early spring As has ALREADY he4n
shown. at this season evaporation. M
aosorpiiNe capacity of tho soil ana
the moisture requirements Of vegeta-
ZION are near A minimum, while rain
fall is more nearly continuous. even if
less Intense than during the growing
months
In determining the size OF channel to
care for tho run-on OF the Chickaholn
my watershed It has seemed wisest to
provide for moderate increase over
aud above this ordinary winter ma
spring stage To do less would not
| provide sufficient outlet and wonlf
leave tho land undraincd and in poor
! condition for carly working and rlant-
ing While II might be desirable to
care for heavy freshet and food dis
| charges to d. moro than as indicated
! above would be unneco ssary ami an
| unwarranted expenditure Of money.
| ON February 25. 1912. a rainfall Of
! Is Inches caused the Chickahominv
| rover to overflow its banks aud To rise
! Throughout the valley to the hish
! water marks noted during tho previous
/ summer. Following this storm. in
crd"r 10 determine tho relation under
actual held conditions between ratio
lf flow and size Of tributary drainage
area or what may he designated the
B unit of drainage run off there were
/ MADE ~ different points six separate
/ current measurements. but each prac-
,'f"lly coinoiacnt with the crest" in
us movement down the valley. The
SHOWN by the hottom curve in figure
. Ihe curve Immediately above. whose
200 NJ
equation Is Q ------. represents the
NJ
! rtn-off provided for by the proposed
new channel. 20" Is the run OF in
cupic rect per second per square mile
OF drainage area and Is plotted on the
a%is OF ordinatcs For convenience in
comparing With rainfalis. the run OF
o"pressed IN depth In inches in TWEEN