Specifications

HYDROLOGICAL SERVICES
DL3 100-018 IMP
Issue 2: 15/11/2005
River Height
Time
Interval
change
in RvH
threshold
RvAl3 = change in River Height / Interval /above threshold
= alarm event satisfied
Note: RvAl3 may occur as the river is falling since the alarm criteria is for absolute change.
Hydrograph
River Alarm 3 (RvAl3)
River Alarm 3 is a rate of change alarm. Alarm checking for RvAl3 will commence once the river
rises above a user defined threshold. Above this threshold an absolute change in river height over a
defined time interval as specified by RvAl3 interval parameter, will trigger an RvAl3 event. Alarm
checking for an RvAl3 condition is then disabled for a period of time equivalent to half the interval
parameter of RvAl3 (interval/2). Alarm checking then recommences immediately after this interval
or if RvAl3 parameters have been re-defined by user command.
River alarm 3 can be individually disabled by entering RVAL3= When the alarm is disabled the
alarm value is displayed as "--.--/--:--/--.--"
On-line Help
RVAL3?
River Alarm 3:If the river changes at a rate > RVAL3 then an alm
mesg is generated, if the river is above user
defined threshold and alm checking is en
yntax: RVAL3<CR> Displays RVAL3 value in feet per time
interval (Hr:min) + the river threshold in metres
RVAL3=003.00/02:30/005.50<CR> Sets parameter to a height change of
3 over the last 2.5 hrs if the river height is > 5.5