13 
damage to agricultural lands and property. Further, there are 
very few natural storage sites in the Territory, and the run-off 
of barren regions may be likened to the run-off from a roof 
without gutters or rainspouts. In a great many locations porous 
or fissured conditions of the drainage areas result in a light 
surface run-off, and a heavy absorption of the rainfall. This 
water may sometimes be picked up by water tunnels or wells, 
but as a rule it appears in springs near or below sea level. The 
comparative cost of irrigating by pumping against the cost of 
surface gravity supplies is too well known to be discussed here. 
With the intermittent rainfall of the Territory, without regula- 
tion of some kind, the resultant run-off of surface streams would 
consist of short periods of high erosive and destructive floods 
followed by long periods of drought. Underground supplies 
would be similarly affected to a less degree. 
“There is but one way by which Hawaiian streams may be 
economically regulated, and that is by retaining or developing 
a heavy blanket of forest cover over as much of the streams’ 
catchment areas as may be consistent with the demand for 
water from these areas. The heaviest rainfall is, with few 
exceptions, above the levels at which agriculture is carried on 
and it is at these upper levels that the heaviest forest cover is 
needed as a water supply regulator. This spongelike cover 
receives and retains the rainfall, and feeds it gradually to the 
surface and underground water sources, serving as a regulator 
to decrease floods and to increase dry season discharge. 
“The United States Geological Survey in collaboration with 
the National Bureau of Forestry, is now making careful and 
detailed experiments in the White Mountains of New Hamp- 
shire on the effect of deforestation and reforestation in its 
relation to surface stream regulation. While these experiments 
have not been completed, the results so far have proved conclus- 
ively that forest cover is a most important factor in the regula- 
tion of stream run-off. In the Hawaiian Islands and under 
tropical conditions, the forest cover is much more dense, and 
the beneficial or destructive effects of forest cover or the lack 
of it is much greater than in the White Mountains. 
“The Territory of Hawaii, has, since 1910 maintained a 
hydrographic survey in cooperation with the United States 
Geological Survey. Limited funds have restricted operations 
to low level accessible localities with insufficient and temporary 
equipment. The 1911 and 1912 reports of this Survey are 
