Question

In Snyder's method of synthetic unit hydrograph development, basin lag is taken as

• A. the time interval between centroid of the rainfall excess and surface runoff
• B. the time interval from mid point of the unit rainfall excess to the peak of the unit hydrograph
• C. independent of rainfall duration
• D. independent of catchment characteristics

Answer 1

The correct option is B the time interval from mid point of the unit rainfall excess to the peak of the unit hydrograph

Synder was the one to develop a synthetic Unit Hydrograph based on a study of watersheds in the Appalachian Highlands. In basins ranging from
$10-10,000‘m{i}^2$
Snyder relations are
$t_p=C_t(L{L}_C{)}^{0.3}$
where,
$t_p$ = basin lag(hr)
$L$ = length of the main stream from the outlet to the divide (mi)
$L_c$= length along the main stream to a point nearest the watershed centroid (mi)
$C_t$= Coefficient usually ranging from 1.8 to 2.2