<Tr> <Td> </Td> <Td> This article is an orphan, as no other articles link to it . Please introduce links to this page from related articles; try the Find link tool for suggestions . (July 2012) </Td> </Tr> <Table> <Tr> <Td> </Td> <Td> This article may be too technical for most readers to understand . Please help improve it to make it understandable to non-experts, without removing the technical details . The talk page may contain suggestions . (March 2012) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article may be too technical for most readers to understand . Please help improve it to make it understandable to non-experts, without removing the technical details . The talk page may contain suggestions . (March 2012) (Learn how and when to remove this template message) </Td> </Tr> <P> A channel section is considered to be most economical or most efficient when it passes a maximum discharge for given cross section area, resistance cofficient and bottom slope . From the equation of continuity it is evident that for area of cross section being constant, discharge is maximum when the velocity of discharge is maximum. and from Chézy formula and Manning formula for a certain value of slope and surface roughness velocity is maximum when the hydraulic radius is maximum. and if we take area as constant hydraulic radius is maximum if the wetted perimeter is minimum. semicircular section is the best economical channel but due to difficulty in creating it, trapezoidal can be considered most efficient . </P>

Most efficient cross sectional shape for an open channel