PCWA-L 467.pdf - PCWA Middle Fork American River Project ...

4, STAGE MEASUREMENT 39
reliable alternating-current power is available.
Digital recorders may miss the absolute peak stage especially on
flashy streams. However, a measure ofthe maximum peak that occurs
between inspections ofthe recorder can be obtained by attaching a wire
clip(similartoa paperclip) orsmallmagnettothefloattapejustbelow the
instrumentshelfinsuch a mannerthatitwill slide along the tape as the
stage rises but remain in a fixed position as the stage declines. (See p.
60-61).
Mechanically punched tape is the most practical for field use under
widely varying conditions of temperature and moisture. Electronic
translators are used to convert the 16-channel punch-tape records to a
tape suitable for input into a digital computer for computation of a
daily mean gage height and daily mean discharge.
In the metric version of the digital recorder, stage is recorded in
increments of 1 millimeter from 0 to 9.999 m.
GRAPHIC RECORDER
The graphic, or analog, recorder furnishes a continuous trace of
water stage, with respect to time, on a chart. Usually the gage-height
element moves the pen or pencil stylus and the time element moves
the chart, but in some recorders those actions are reversed. In the
U.S.A, the common range of available gage-height scales is from 10
in=1 ft (10:12) to 10 in=20 ft (1:24), The width of strip charts is
usually 10 in (0.25 m). The range of available time scales is from 0.3
to 9.6 in