| OCR Text |
Show Although all rivers naturally 94 seek meandering courses ( , ) ) ( with vith ) resultant swifter current and ( well- well -well- well ) defined channels next to the concave shore , if they are to arrive finally at a destination , reverse curves are ( necessaiy necessary ) . ' With few exceptions crossing bars are coincident with all ( such stich ) reversals . It is apparent that the reversal of the current ( from froin ) one ( "bank bank bank ) to the other is the primary cause of ( crossing cro8ing ) bars . ( Photo 5 , ( Exhibit Rx-hibit Rxhibit ) 145 . ) These bars extend across the river diagonally and average in length from 1,000 feet to more than 3,000 feet . It is evident that when the river is at flood stage the channel is full froni bank to bank . Velocities in the cross sections are , however , known to vary within wide limits , even where the cross section is regular and the channel straight . ( Eacli Each ) ( change chancre ) in the cross section or direction of the river is attended by a redistribution of velocities in the ( cross cToss ) section and a change in the direction of the thread of maximum velocities . These changes in velocity give rise to the formation of whirlpools , eddies , and backwater with the resultant decrease in the ( ve- ve ) , locity and a partial or complete deposition of ( sedi sedi- sedi ) ment carried in suspension or as bed load . When the direction of current is changed as a result of a * reversal of curvature of the ( channel chaniael ) , ( there theTe ) is change in the distribution of velocities , The thread of maximum velocity which , as a result of centrifugal force , follows the concave bank is diverted ( diag cUag- cUag ) onally across the channel and downstream . The reduction in the velocities parallel to the thread of |
