In the Snyder synthetic unit hydrograph method, the lag time tp (hours) from centroid of rainfall to peak of UH is:
Choose the correct answer
tp = Ct x (L x Lc)^0.3
tp = Ct x (L x Lca)^0.3 (where Ct = basin coefficient, L = main stream length in km, Lca = distance from outlet to point on stream nearest catchment centroid)
tp = peak discharge / area
tp = time of concentration only
Correct Answer
B. tp = Ct x (L x Lca)^0.3 (where Ct = basin coefficient, L = main stream length in km, Lca = distance from outlet to point on stream nearest catchment centroid)
Why is this the answer?
Snyder UH: tp = Ct(L x Lca)^0.3; qp = Cp x A / tp (Cp = peaking coefficient); peak duration t_R = tp/5.5; T_b (base time) = 3 + tp/8. Ct = 1.35-1.65 (steep), Cp = 0.4-0.8. Synthetic UH is used when no gauge data available for the catchment.
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