The shape of the recession limb of a hydrograph depends upon

Concept:

Hydrograph: It is a continuous plot of instantaneous discharge (runoff) v/s time.

It results from a combination of physiographic and meteorological conditions in a watershed and represents the integrated effects of climate, hydrologic losses, surface runoff, interflow, and groundwater flow.

Factors that influence the hydrograph shape and volume

i. Meteorological factors

ii. Physiographic or watershed factors and

iii. Human factors

Flood hydrograph has three characteristic regions:

(i) Rising limb AB: Curve Joining point A, the starting point of the rising curve and point B, the point of inflection. It is concave in shape and the shape depends both upon the rainfall and the catchment parameters.

(ii) Crest segment BC: Between the two points of inflection B and C with a peak P. For large catchments it generally occurs sometimes after the rainfall has ended.

(iii) Falling limb/ Recession Limb: Curve CD starting from the second point of inflection C and the shape depends only on catchment parameters (Basin characteristics only) as the rainfall has ceased by then.