Localscourmayoccurwhenahydraulicstructureispositionedinachannelwithanerodiblebed.Herewithinvestigatedexperimentallyaretheerosionandflowpatternduetoawaterjetpassingoverachannelbedattheasymptotic(final)state.Thedevelopmentofthescourhole,itsmaximumscourdepthandlength,arerecordedandcomparedwithavailablescour-depthrelations.Twosetsofexperiments(seeTable1)werecarriedout.Set1(3runs)wasconcernedwithmeasuringtheverticalinstantaneousvelocitydistributioninthescourhole.Thescourholeattheasymptotic(final)state,t≈100[h]wasinvestigated.Set2(5runs)wasconcernedwithstudyingthephysicsofscouring.Thescourholeataboutmid-state,t≈0.5[h],wasinvestigated;subsequentlythescour-holedepthwaslinearlyextendedonthesemi-logscaleto72[h];novelocitymeasurementswereperformed.Thepresentdataareputincontextwithsome(popular)existingrelations;recommendedisamodificationofsomeoftheserelations.
