Specifications

HYDROLOGICAL SERVICES
DL3 100-031 IMP
Issue 2: 15/11/2005
DO
WE HAVE A LAST
TREND BIAS ?
Goto last River Height
Event Record
IS
EVENT WITHIN
INTERVAL ?
Get Next Event and
determine Trend Bias
N
Y
Y
No River Height event within interval.
Trend = 0, Time = interval
Trend bias = rising or falling (+ or -)
IS TREND
BIAS SAME AS LAST
TREND BIAS ?
IS NEXT
EVENT WITHIN
INTERVAL ?
N
N
Y
Y
A change in trend has been detected.
Trend = RvH(most recent) - RvH(oldest within interval of same trend)
Time = difference between now and oldest event within interval of
same trend bias.
Trend = RvH(most recent) - RvH(next event outside interval)
A constant trend.
N
Time = Interval
boundary is that of the next event outside the interval.
3. The Trend value = the most recent event within the time interval prior to now,
minus the oldest event within that time interval of the same trend bias.
4. The Trend time = default time interval, unless a change of trend bias is
detected within the interval then, Trend time = difference between now and the
event time of the oldest event of same bias within the trend time window
.
The River Height Peak (RvHp)
The river height peak will be checked every river height event against the previously recorded
peak (maximum). For a steadily rising river, the peak parameters (RvHp, RvHpT & RvHpD) will
update each event increment until such time where the river height ceases to rise. The peak
parameters will then be maintained for a period of 24 hours unless a new peak occurs, after which
time RvHp, RvHpT and RvHpD will reset and take on the present values of River Height, Time
and Date.
The following flow chart identifies the program logic to determine river height
peak parameters.