SOP for Flood Forecasting & Early Warning - UNESCO Islamabad

Heaviest and the most frequent summer rainfall. occurs within the upper catchment of
river Chenab, making it to be the most flood prone river of the Indus river system, while
Indus being mainly the snow fed river is the least flood affected river of the basin.
2.2 Flood Forecasting System
Process of flood generation undergoes three stages of development.
a) First is the precipitation stage during which the excessive rains occur over the
upper catchments of the rivers. Most of these catchments are mountainous areas
lying on both sides of the border between Pakistan and India/held Kashmir.
Prediction and monitoring of this rainfall forms the meteorological component of
the flood forecasting system.
b) Next is the flood formation stage which starts with the generation of runoff to
form ultimately a flood wave at the confluence of the incremental flood flows.
Forecasting of the flood flows using the actual and predicted rainfall and the flow
data of the upstream stations constitutes the hydrorneterological component of the
flood forecasting system.
c) Lastly, the routing of the flood wave below the rim station of the rivers at the
downstream sites is the hydrological component of the forecasting system. The
flood wave while traveling from one site to another site takes some time. FFD on
the basis of previous record and history has calculated the travel time from one
site to another site for an average flood wave. Travel time is shown in table 1"+:
c:\documents and settings\administrator\desktop\cd material nust\international training workshop\session 5\2_sop pmd_51 pages.doc