Khawaja Zaheer Ahmed - PDMA

Embankment A wall or bank of earth or stone built to prevent a river
flooding an area – also called a levee, dyke or bund.
Flash Flood A flood that rises rapidly, with little or no advance warning.
Flood Plain The entire area subject to overflow by the river course in
flood, mostly formed by the gradual deposits of sediments
on delta lands, causing it to advance further and further
into the sea.
Free-board The distance between the designed full supply level and
top of the sides of an open channel or masonry work left to
allow for wave action, floating debris, or any other
condition or emergency without over-topping banks of the
channel sides of the structure. The vertical distance
between the flood level and the top of the embankment, or
other specified structure.
Glacis The sloping floor below and in continuation of the raised
crest of a weir.
Groyne A spur constructed with more permanent materials as an
obstruction of stone, timber, or brushwood from the
embankment of a river, for diverting or holding the flow. A
stone groyne is called a spur. When the groyne is
constructed parallel to the river flow, for the purpose of
protection against wavewash, it is called a “longitudinal
groyne,” or “muhari”.
Guide bank The embankments forming the upstream and downstream
approaches of a weir. The nose of guide bank is heavily
`stone pitched to withstand river action. A protecting and
training bank constructed to guide the river through the
waterway provided. A river bund may in effect, be a guide
bank when it is at the edge of the river course, there being
little or no foreshore between the river course and the toe
of the bund, e.g., the Jamshoro Bund.
Headworks The works constructed at the off-take of a main canal. It
includes the weir on a river, the dam at storage site, etc.
High Flood Level The highest recorded flood level a river has ever attained
in any previous year (since 1914), at a given point. The
bund is, however to be designed for, or maintained to, “the
Designed High Flood Level (D.H.F.L.) which is the
assumed H.F.L. “or the “extrapolated H.F.L.”, whichever, is
higher.
Hydrograph 1) The curve resulting from the plotting of discharges
against each day of the year.
2) A graph showing the gauge (or discharge) with respect
to time.
Hydrology The branch of science concerned with the properties of the
earth’s water, especially its movement in relation to land.
Inundation Canal A canal dependent upon the surface level of the water in
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