Free Web Tool · Hydrology

Unit Hydrograph

Synthetic unit hydrograph for ungauged watersheds — SCS triangular (qp, tp, tb) and Snyder (lag tp, peak Qp).

Input

SCS only

Results

Lag time tp (hr)
Peak time Tp (hr)
Peak discharge qp (m³/s)
Base time tb (hr, SCS only)
Volume check (m³ from 1 mm)
Method

SCS triangular: Tp = tr/2 + tp; tp = 0.6·Tc; for 1 mm runoff over A, qp = 2·V/(Tp·3600·1.67), tb = 2.67·Tp. Snyder: tp = Ct·(L·Lc)^0.3 [hr]; Qp_per_km² = Cp·640/tp [cfs] or in SI Qp = 2.75·Cp·A/tp [m³/s].