Prediction of disaster occurrence or various standards for warning and evacuation are
shown by a single indicator such as rainfall. All real-time rainfall data (from a
telemetry unit) are available at DID in the existing online server which is in
placed at DID headquarters. The rainfall records in small time-steps or duration
(i.e. 1 minute to an hour) are easily extracted.
The DMFWS in Cameron Highlands and any highlands is possible to be developed by
using a single indicator, rainfall. It is automatically transmitted from remote
telemetry unit (RTU) to DID Headquarters which will be automatically processed
and analysed to give the landslide forecast and warning.
The warranted rainfall (Rw) is a cumulative rainfall that takes into account the
effect of an antecedent rainfall. In general, debris flow occurs under the influence
of not only debris flow causing rainfall but also antecedent rainfall. In the
following figure 1, the standard line indicating the standard rainfall for warning
is called the "Warning Line (WL)" and the standard rainfall for evacuation is called
the "Evacuation Line (EL)". The upper right side of the boundary line is the unsafe
zone where debris flow may occur and the lower left side of the line is the safe zone
where a debris flow may not occur. This boundary line is called "Critical Line (CL)".
The WL and EL are set in consideration of an estimated rainfall during the spare hours
(forecasted rainfall) and the critical line (CL).
Figure 1: Shows the Model of DMFWS is ready to be activated and run the model.
The snake line is the line that shows the changes of two rainfall indices with time,
as seen in Figure 2 . In this figure, the snake line depicts at an interval of one hour.
The warranted rainfall derives by the addition of the antecedent working rainfall to the
continuous rainfall. The snake line in the figure always goes upward relative to the
abscissa during the period of rain. As a result, if moderate amount of rainfall continuous
for fall for a long time or during a prolong rainfall event, the snake line will still
be possible to exceed the WL and progressively proceeds to the EL of exceeded period will
drag on. This causes a problem especially when attempting to cancel or issue a warning or
an evacuation instruction, since the affected people would not like to be evacuated for
prolong a period of time.
Figure 2: The model activated and produced On-Line Monitoring or a Snake Line in blue colour