ABSTRACT
Graniteorconcretesetts Graniteorconcretesettscanbeusedtoformchannels,andtheirconstructionis simUartothatofbrickchannels.Thesesmallerunitscanbemoreatttactivethan brick,andarewellsuitedtoconservationworlc.Cobblesaresometimesusedfor channels,butunlesstheyarelaidlowenoughtoallowthewatertorunfreely(in whichcasetheydonotshowmuch)theyareonlyaUttertrap.Cobblesdohavean advantageonsteepslopesinthattheyretardtheflowofwatertosomeextent,so preventingarushofwaterdowntheslope.
