Isochrones on a catchment map are lines joining points of:
Choose the correct answer
Equal rainfall depth
Equal time of travel of surface runoff to the outlet, used to construct the time-area diagram for determining the IUH (Instantaneous Unit Hydrograph)
Equal elevation (contours)
Equal infiltration rate
Correct Answer
B. Equal time of travel of surface runoff to the outlet, used to construct the time-area diagram for determining the IUH (Instantaneous Unit Hydrograph)
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Isochrones: lines of equal travel time t from each point on catchment to the outlet. The area between successive isochrones (time-area histogram) represents the runoff contribution rate at that time lag. The time-area diagram is convolved with the excess rainfall intensity to produce the direct runoff hydrograph (Clark method for IUH).
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