re was in
the flood of 1903 a larger rainfall during a much shorter period than in
the flood of 1902. Computation shows that the total run-off from the
drainage area above Dundee dam during the earlier flood was
13,379,000,000 cubic feet, and that on account of the frozen condition
of the ground at that time this amount of water represented practically
all of the precipitation. During the flood of 1903 there was a total
run-off for the same area of 14,772,000,000 cubic feet, which represents
about 66 per cent of the observed precipitation. According to these
figures the total amount of run-off in the 1903 flood was only 10 per
cent greater than that in 1902, while the actual flood height during the
1903 flood was 27 per cent higher than during the flood of 1902. The
above comparison shows, in a striking manner, the effect of the
condition of the surface. In the case of the later flood we had, as has
been stated in previous pages, an area which had been well watered
during the previous summer, and the observed ground-water levels were
fairly high. There was, however, sufficient storage capacity in the
basin to retain about 34 per cent of the precipitation occurring between
October 7 and 11. This water must have been largely absorbed by the
earth. The general relations of the floods of 1903 and 1902 can
therefore be briefly stated as follows:

_General relations of floods of 1903 and 1902._

-----+--------------+--------------+-------------+------------->
|Average | Duration of | Maximum | Total
|precipitation.|precipitation.| flood flow. | run-off.
| | | |
-----+--------------+--------------+-------------+------------->
| _Inches._ | _Days._ |_Sec.-feet._ | _Cubic feet._
1902 | 6 | 6 | 24,800 |13,379,000,000
1903 | 11.74 | 3 | 35,700 |14,772,000,000
-----+--------------+--------------+-------------+------------->

<-----------+-------------
Run-off. | Duration of
| flood at
| Dundee dam.
<-----------+-------------
_Per cent._| _Hours._
[B]100 | 270
66 | 225
<-----------+-------------
[Footnote B: Approximately]

In the following table and fig. 2 are recorded gage heights taken at
hourly intervals during the crucial part of the flood and the amount of
water expressed in cubic feet per second flowing over the crest of the
dam at each gage