Question

Which of the following stilling basin is applicable to only rectangular cross-sections?

(a) U.S.B.R stilling basin-II

(b) U.S.B.R stilling basin-IV

(c) U.S.B.R stilling basin-I

(d) U.S.B.R stilling basin-III

This question was posed to me in a dream while sleeping

Enquiry is from Energy Dissipation Below Overflow Spillway in chapter Spillways, Energy Dissipators and Spillway Gates of Irrigation Engineering

Answer 1

Right answer is (b) U.S.B.R stilling basin-IV

To explain I would say: USBR stilling basin-IV is used for Froude number varying between 2.5 and 4.5 which generally occurs in canal weirs, canal falls, diversion dams, etc. They are tried to be controlled by providing large chute blocks since oscillating waves are generated in this range. This is applicable only to rectangular cross-sections.