The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1885-1921, 1896-07-02
WATER POWER
OF ISLAND OF OAHU.
Prof. Maxwell Gives Some Val
liable information,
POSSIBLE SUGAR PRODUCTION.
Can be Increased Three FoId-ScIenti-
fic study of Terrestrial Conditions. !.
Water Running to Waste-Op-
portunity for Developments, Etc.

Usually the term '.water-power" is
used to express the mechanical equiva-
lent and value of body or flow of
water for industrial uses. There are
situations, however, where natural con-
ditions, and among these specially the
character of the geological structure of
the underground, prevent a regular sur
face flow by streams, even where the
rainfall is ample, and in such cases-a
notable one obtaining on this island
value for the power-equivalent of the
rainfall may be sought in directions of
a non-mechanical character.
To approximate the available value
of the water-power of given area it is
necessary first to estimate the volume
of the natural rainfall, and then to fol-
low it's several modes of discharge and
waste.
After careful examination of rain
fall data, comparing the relative pre-
cipitations over the several areas of
different altitude, we are induced to
place the average rainfall of Oahu at
70 inches The data available, how
eyer, are very Inadequate for anything
more than a distant approximation to
the actual, and we are, IN certain locali-
ties, having gauges placed at all alti-
tudes, and of such form that the rain
fall will need to be measured only once
a month, in order to secure actual data.
For the purpose of the following con-
siderations we shall base our calcula-
tions upon an annual rainfall of 60
inches, which certainly keeps within
the actual precipitation.
The surface area of Oahu is esti-
mated by measurement at 600 square
miles, which is equal to 2 ,408, ,693, ,760 900
square inches. Upon this area an an
nual rainfall of so inches would give
IA, ,521, ,625, 800, 900 cubic inches of rain
If this latter sum be resolved into gall
Ions we obtain the total of 625, ,634 ,742,-
S57 gallons, which sum will be taken
as basis of the following considera-
tions
Having reached some approximation
to the volume of annual rainfall upon
Oahu, we may proceed to consider the
of water which escape by the |
several modes of discharge and waste. |
The three chief modes by which rain |
fall is discharged from the surface |
where it falls are: () Surface drainage, |
by bitches and streams. (2) Surface |
direct and through vege- |
alton. 90 Percolation through soil and |
rock strata, and discharge by springs |
at lower attitudes.
1t is at once apparent that the |
of water which shall be dis |
in these several ways must be |
extremely various, and are controlled
by sucn factors as the level or hilly
surface of the land; the porous or close
texture of the surface and under soil;
the temperature of the air; ard the vio-
lent or steady rate of precipitation of
the rain. There are localities where the
rainfall is so small that neither surface
nor underground drainage occur; the
whole of the precipitation being re-
turned to the air by direct evaporation
or the Transportation of plants. Again,
there are localities where the surface
and under strata are so open that sur
face drainage is equally as impossible
the whole of a large rainfall passing
into the soil and, in part being re-
turned to the air, and in greater part
being discharged by underestimate. For
example, on the Waiakea side of the
Hilo river, upon the Waiakea pIanta-
ton, the rainfall is about $50 inches
per annum; yet there is not one run
ming stream, the whole of that i'm
mense body of water being discharged