THE TRANSPORTATION OF DEBRIS BY RUNNING WATER

AN INVESTIGATION WAS CONDUCTED TO LEARN THE LAWS WHICH CONTROL THE MOVEMENT OF BED LOAD, AND DETERMINE HOW THE QUANTITY OF LOAD IS RELATED TO THE STREAM'S SLOPE AND DISCHARGE AND TO THE DEGREE OF COMMINUTION OF THE DEBRIS. LABORATORY EXPERIMENTS WERE CONDUCTED IN WHICH EACH OF THE THREE CONDITIONS MENTIONED WERE SEPARATELY VARIED AND THE RESULTING VARIATIONS OF LOAD WERE OBSERVED AND MEASURED. SAND AND GRAVEL WERE SORTED BY SIEVES INTO GRADES OF UNIFORM SIZE. DETERMINENT DISCHARGES WERE USED. A SPECIFIC LOAD WAS FED TO A STREAM OF SPECIFIC WIDTH AND DISCHARGE IN EACH EXPERIMENT, AND MEASUREMENT WAS MADE OF THE SLOPE TO WHICH THE STREAM AUTOMATICALLY ADJUSTED ITS BED SO AS TO ENABLE THE CURRENT TO TRANSPORT THE LOAD. FOR EACH COMBINATION OF DISCHARGE, WIDTH AND GRADE OF DEBRIS THERE IS A SLOPE, CALLED COMPETENT SLOPE, WHICH LIMITS TRANSPORTATION. FOR EACH COMBINATION OF WIDTH, SLOPE, AND GRADE OF DEBRIS THERE IS A COMPETENT DISCHARGE. FOR EACH COMBINATION OF WIDTH, SLOPE, AND DISCHARGE THERE IS A LIMITING FINENESS OF DEBRIS BELOW WHICH NO TRANSPORTATION TAKES PLACE. THE VELOCITY WHICH DETERMINES CAPACITY FOR BED LOAD IS THAT NEAR THE STREAM'S BED, BUT ATTEMPTS TO MEASURE BED VELOCITY WERE NOT SUCCESSFUL. MEAN VELOCITY WAS MEASURED INSTEAD. IT WAS FOUND THAT DEBRIS COMPOSED OF PARTICLES OF A SINGLE SIZE IS MOVED LESS FREELY THAN DEBRIS CONTAINING PARTICLES OF MANY SIZES. SOME PARTICLES OF THE BED LOAD SLIDE, MANY ROLL, THE MULTITUDE MAKE SHORT SKIPS OR LEAPS, THE PROCESS BEING CALLED SALTATION. THE ENERGY OF A STREAM IS MEASURED BY THE PRODUCT OF ITS DISCHARGE (MASS PER UNIT TIME), ITS SLOPE, AND THE ACCELERATION OF GRAVITY. EACH ELEMENT OF LOAD BY DRAWING ON THE SUPPLY OF ENERGY, REDUCES VELOCITY AND THUS REDUCES CAPACITY FOR ALL PARTS OF THE LOAD. THIS PRINCIPLE AFFORDS A CONDITION BY WHICH TOTAL CAPACITY IS LIMITED. SUBJECT TO THIS CONDITION A STREAM'S LOAD AT ANY TIME IS DETERMINED BY THE SUPPLY OF DEBRIS AND THE FINENESS OF THE AVAILABLE KINDS. CAPACITIES WERE FOUND TO BE NOTABLY LARGER FOR FLUME TRANSPORTATION THAN FOR STREAM TRANSPORTATION, AND THEIR LAWS OF VARIATION ARE DIFFERENT.

  • Supplemental Notes:
    • Prof Paper 86, 263 PP, 89 FIG, 83 TAB
  • Corporate Authors:

    U.S. Geological Survey

    F Street Between 18th and 19th Street, NW
    Washington, DC    20244
  • Authors:
    • Gilbert, G K
  • Publication Date: 1914

Subject/Index Terms

Filing Info

  • Accession Number: 00204137
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Aug 12 1994 12:00AM