MODEL TEST OF BOX INLET DROP SPILLWAY AND STILLING BASIN PROPOSED FOR TILLATOBA CREEK, TALLAHATCHIE COUNTY, MISS.

THE EXPERIMENTAL DESIGN OF THE RIPRAP IN THE APPROACH AND EXIT CHANNELS AND THE DEVELOPMENT OF A SPILLWAY CREST TO FIT A PREDETERMINED HEAD-DISCHARGE RELATIONSHIP REPORTED HERE FOR A BOX INLET DROP SPILLWAY PROPOSED FOR TILLATOBA CREEK, TALLAHATCHIE COUNTY, MISS. EXCESSIVE SCOUR IN THE APPROACH CHANNEL NEAR THE STRUCTURE WAS ELIMINATED BY ADDING RIPRAP PROTECTION. THE AREAS TO BE PROTECTED BY EACH RIPRAP SIZE WERE DETERMINED FROM ISOVELS MEASURED IN THE APPROACH CHANNEL. THE SIZES OF RIPRAP REQUIRED TO RESIST MOVEMENT CAUSED BY THE ACCELERATING VELOCITIES APPROACHING THE STRUCTURE WERE BASED ON THE MANNING FORMULA. IN THE MANNING FORMULA THE BED ROUGHNESS WAS RELATED TO THE MEAN RIPRAP SIZE, AND THE SLOPE OF THE HYDRAULIC GRADE LINE WAS EVALUATED FROM THE CRITICAL TRACTIVE FORCE USING THE CRITERIA DEVELOPED BY A. G. ANDERSON ET AL., ST. ANTHONY FALLS HYDRAULIC LABORATORY, UNIVERSITY OF MINNESOTA. THE DROPDOWN OF THE OVERBANK FLOW INTO THE APPROACH CHANNEL NEAR THE STRUCTURE AND THE RESULTING EROSION OF THE APPROACH CHANNEL BANKS WERE ELIMINATED BY DESIGNING THE BOX INLET CREST SO THE HEAD ON THE CREST AT BANK-FULL DISCHARGE WAS EQUAL TO THE DEPTH OF FLOW. THE DEVELOPED CREST SHAPE IS THAT OF A COMPOUND TRAPEZOIDAL WEIR. EQUATIONS FOR THE COMPOUND TRAPEZOIDAL WEIR HEAD-DISCHARGE RELATIONSHIP WERE DERIVED. THE DISCHARGE COEFFICIENTS IN THE EQUATIONS WERE DETERMINED AND CHECKED AGAINST THE OBSERVATIONS. THE AGREEMENT WAS WITHIN 6 PERCENT. THE SELF-FORMED SHAPE OF THE SAND-BED DOWN-STREAM CHANNEL WAS DETERMINED. SITE REQUIREMENTS NECESSITATED MODIFICATIONS OF THIS SHAPE. EXPERIMENTAL DESIGN METHODS WERE USED TO DETERMINE THE PLACEMENT AND SIZES OF RIPRAP REQUIRED TO PROTECT THE DOWNSTREAM CHANNEL. THE EFFECT OF TAILWATER DEPTHS LESS THAN THE DESIGN DEPTH WAS SHOWN TO BE MINIMAL. /AUTHOR/

  • Supplemental Notes:
    • ARS-NC-3
  • Corporate Authors:

    Agricultural Marketing Service

    Independence Avenue, Between 12th and 14th Streets, SW
    Washington, DC  USA  20250
  • Authors:
    • Blaisdell, F W
  • Publication Date: 1973-1

Media Info

  • Features: Figures;
  • Pagination: 50 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00204523
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jan 28 2003 12:00AM