EVALUATION OF RUNOFF COEFFICIENTS FROM SMALL NATURAL DRAINAGE AREAS

THE KENTUCKY DEPARTMENT OF HIGHWAYS, AS DO MOST OTHER AGENCIES WHICH BUILD SMALL DRAINAGE STRUCTURES, ESTIMATES FLOOD PEAKS AS A FUNCTION OF RUNOFF COEFFICIENT, RAINFALL INTENSITY, AND DRAINAGE AREA. AVAILABLE PROCEDURES WERE APPLIED TO 39 GAGED WATERSHEDS IN AND NEAR KENTUCKY AND COMPARED WITH THE RESULTS OF FREQUENCY ANALYSIS OF HISTORICAL STREAM GAGE RECORDS. THE METHODS CONSISTENTLY UNDERESTIMATED THE FLOOD PEAK. THEREFORE, A MORE INTENSIVE STUDY (USING THE STANFORD WATERSHED MODEL) OF THE RUNOFF COEFFICIENT WAS UNDERTAKEN BY DIVIDING IT INTO OVERLAND FLOW AND STREAMFLOW COMPONENTS. A SET OF CURVES WAS DEVELOPED BASED ON THE 50-YEAR EVENT AT LEXINGTON, KENTUCKY, TO ESTIMATE THE PEAK RATE OF OVERLAND FLOW AS A FRACTION OF RAINFALL INTENSITY FROM FIVE MEASURABLE WATERSHED CHARACTERISTICS (SIL DEPTH, PERMEABILITY, OVERLAND SLOPE, IMPERVIOUS AREA, AND SOIL SURFACE EXPOSURE). THE STREAMFLOW COMPONENT WAS NOT STUDIED. A STUDY WAS MADE OF THE VARIATION OF THE RUNOFF COEFFICIENT WITH MEAN ANNUAL RAINFALL, RAINFALL INTENSITY, AND FREQUENCY. THE INVESTIGATION WAS BASED ON APPLYING THE STANFORD WATERSHED MODEL TO SIX HOURLY-RAINFALL RECORDS. THE RESULT WAS A SET OF CORRECTION FACTORS TO APPLY TO THE OVERLAND FLOW VALUES ESTIMATED FROM WATERSHED CHARACTERISTICS. /AUTHOR/

  • Supplemental Notes:
    • Research RePORT 14, 112 PP
  • Corporate Authors:

    University of Kentucky, Lexington

    Water Resources Institute
    Lexington, KY  United States  40506
  • Authors:
    • Miller, C F
  • Publication Date: 1968

Subject/Index Terms

Filing Info

  • Accession Number: 00204184
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 28 1994 12:00AM