An idealized catchment can be represented as two circular sectors as shown in the figure.
The left portion of the watershed has a radius of 360 m and the
associated loss coefficient (loss index) φ1 = 10 mm/hr. The right
portion of the watershed has a radius of 540 m and φ2 = 20 mm/hr.
Both sectors are one eighth of a complete circle in area. The flow
velocity is assumed to be toward the center of the circular arcs in both
sections and have an average value of 0.1 m/s.
Determine:
a) The time of concentration of this watershed and draw the 30
minutes isochrones;
b) The direct runoff hydrograph from one-hour excess rainfall of 25
mm
c) The response of this watershed to the rainfall accumulations
shown below (discharge values should be given in m3
/min)