SOME MEASUREMENTS OF VELOCITIES AND SCOUR AT A MISSISSIPPI RIVER BRIDGE PIER

A STUDY OF SCOUR RESULTING FROM THE CONSTRUCTION OF TWO PIERS IN THE CHANNEL OF THE MISSISSIPPI RIVER WAS MADE DURING THE CONSTRUCTION OF THE BRIDGE AT BATON ROUGE, LOUISIANA. THIS STUDY INCLUDED SOUNDINGS TAKEN AT HIGH AND LOW WATER STAGES ON RANGES EXTENDING ABOUT 1000 FEET UP AND DOWN STREAM FROM THE BRIDGE CENTERLINE AND VELOCITY READINGS ON TWO RANGES, ONE ON THE BRIDGE CENTERLINE AND THE OTHER UPSTREAM, AT ONE OF THE PIERS. THIS PAPER REPORTS THE RESULT OF THIS FIELD STUDY AND POINTS OUT THE EFFECT OF THE CONSTRUCTION ON THE STREAM BED AND THE CHANNEL CROSS SECTION. THE EXAMPLE CITED BRINGS TO ATTENTION THE DANGER OF DAMAGING SCOUR IN STREAMS HAVING ALLUVIAL BEDS AND SHOWS THE VELOCITY AT VARYING DEPTHS AT A FLOOD HEIGHT THAT RESULTED IN A CUTTING OUT OF THE STREAM BED ADJACENT TO THE CHANNEL OBSTRUCTIONS AND AFFECTED THE RIVER CROSS SECTION MATERIALLY UP AND DOWN STREAM. THE DATA REPORTED IS TO ENCOURAGE THE FURTHER STUDY OF A PROBLEM ON WHICH LITTLE RESPONSIBLE DATA IS AVAILABLE AND TO CALL ATTENTION TO THE NEED FOR COORDINATING KNOWLEDGE OF STREAM FLOW AND SOILS CHARACTERISTICS TOWARD A SOUND BASIS ON WHICH SCOUR EFFECTS AT BRIDGE PIERS MIGHT BE PREDETERMINED WITHIN REASONABLE LIMITS. /AUTHOR/