Define the following terms as applied in hydrologic analysis (i) travel time (ii) bifurcation
ration (iii) drainage density (iv) excess rainfall (v) Surface water (vi) Abstractions (vii) Rating
curve (Viii) Phi-index (ix) Curve number
Consider a catchment of 33.3 km
situated in an arid region. The outlet of the catchment is a dry
river that carries water only after heavy rainfall. A rainstorm with a depth of 100 mm falls
uniformly over the catchment during a period of three hours. The rainfall depth in the first,
second and third hour are respectively 45, 35 and 20 mm. The discharge at the outlet due to
this rainstorm is presented as hydrograph A (solid line) in the chart below.
Compute the runoff coefficient for this rainfall event.
b Compute the constant loss rate (the
In the same chart the hydrograph observed at a point B, 20 km downstream in the
same river is plotted. The average width of the river section between A and B is 50 m.
Estimate the average infiltration rate into the river bed between A and B in mm/hr
during the passage of the flood wave.