investigation of effect porosity on scour depth around l-head groins with clapper toward downstream and upstream under clear water condition

abstract the groines are structures which are use to protected the river bank and to form the water way .the most important problem of groynes is scour at around it that makes breaking and overturning the groynes. because of the less researches at about l-head groynes and open groynes ,this article considers the amount of scour in this type of groynes. so because of this have been used the lace gabions full of rock for producing the open groynes and considered effect the amount of porosity of gabion on scour of l-head groyne with clapper to down stream. results show that for 40-50% of porosity, lower scour at around groin with clapper toward downstream occurs and the maximum scour around the groin with clapper toward upstream can be observed.