ROUGHNESS PARAMETER OF OPEN CHANNEL

Abstract

Ttio thesis describes the 1nvos igations ca iod out by the author on some aspect of the resistance of artifL ctal2,g ugiaonod open chanGls in relation to those of alluvial ohannoic 2 he studios aimed st predicting the roughness p1'EOtGD5 for open ch3flf101S ith special reference to r bilo boundaries. These have hver, 'won confined to flume studies only. The causing literature on the sbboot has first been revt sd and the studies were then. carried, out& On the basis of the dimensional analysis done In chapter 1I; it. has been shown that M f ( RG Fri I g) (1) B , QrO V , Is the mean velocity of slow "o I s the shear velocity = Re is the Roynoldg number Fr i3 the Freude numbo at is the tiyPulit radius i4th respect, to bad. h i s the l 9ht C t roubhriess. element ' is the spacing of roughness element B I s the vi dth of the flume, 3be an. .ysi of the artificial. roughness dot* of the present investigation revesjed tb t the o locaity dirt i UUon in the vertic0i in open Channel can be Qzresscd as log ( EL ) s in gbtcb Is Is ega1valont roughnossp a length parameter ch takes into aocouint the effect of shape and density of roughness and of flow aharaetorIstIcso K Is the Korman° constant* The so oslled KSPfflQUC $ constant V Is shown Va to be1longer a constant ( i = M. ) but varies d th the t condi tIons, sediment and roughness cbaractoristics. Oct + omperisinn of the data of rigid bound.cries with those of mobile boundaries, it has been found that size and shape of the gr Lus, of which the boundary constitute ) plays an Important role in deVGlOpi2Z bed fosse In such Channels the major port n of the drag is the form.drag which goes on decreasing as the bed flattens. The roughness to flow In alluvial channels has been shot to be governed, mostly by the parameters c R and 'ro 6