SOP for Flood Forecasting & Early Warning - UNESCO Islamabad

Chapter 1
Flood Causes & Management
1.1 Define Floods
Flood is defined as the high stage of a river at which the stream channel gets filled up and above
which it overflows its banks and inundates the adjoining areas.
1.2 Classification of Floods
In Pakistan, floods are classified into five levels, shown in Table (1.1).
Table 1.1 Classification of floods
S.No. Classification Detail
1. Low Flood It is that flood situation when the River is flowing within
deep channel(s) but is about to spread over river
islands/belas.
2. Medium Flood The river is called in Medium Floods when River flows is
partly inundating river island/belas but below half of its
highest flood level
3. High Flood When the water level of the River is almost fully
submerging islands/belas and flowing upto high
banks/buds with encroachment on freeboard.
4. Very High Flood When the water level of the river flows is between high
banks/bunds with encroachment on freeboard.
5. Exceptionally High
Flood
It is that flood situation where there is imminent danger of
overtopping/breaching or a breach has actually occurred or
high bank areas become inundated.
1.3 Flood Limits of the River/Nullah
The limits of the flood in different rivers/nullahs at different places are shown in
Table 1.2 & 1.3
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