Release Time Component of a Hydrograph

Excess rainfall release time is one of the most important temporal components of a hydrograph and is often equated with time of concentration; however, this study will demonstrate that these two components are basically different and must be discriminated from each other. A formula for estimation of release time principled on Clark hydrograph is also proposed. This research introduces another concept of partial release time, and a parametrical equation for its estimation is suggested. Furthermore, the fundamental relation between time base and excess rainfall duration for linear systems is clarified, giving rise to a formula for time base of Clark hydrograph. Finally, it will be theoretically shown that release time is the temporal dependency between the rainfall and runoff in each event, and hence it plays a crucial role in event-based rainfall–runoff-forecasting models.

Varmaghani, A., and Ghiassi, R. “Release Time Component of a Hydrograph.” J. Hydrol. Eng., DOI:10.1061/(ASCE)HE.1943-5584.0000790, pp. 444-447, 2014.