ABSTRACT:
Runoff curve numbers for sugarcane and pineapple fields in Hawaii were derived from rainfall and runoff data collected during a 7-year study between 1972 and 1979. The new curve number values were used to modify previously determined values based on 5 years of data and to adjust Soil Conservation Service handbook values. Handbook values were based mainly on experience obtained under mainland conditions and soils. The data-based curve numbers were slightly lower than previously used handbook values for sugarcane fields. The greatest differences were for porous A soils and complete cover conditions. The data-based curve numbers were considerably lower than handbook values for pineapple fields, where field roads occupied 11 to 20 percent of the area. The greatest differences were noted after pineapple had reached the partial or complete cover stage, indicating that pineapple provides more protection than expected once it covers at least 50 percent of the field surface. Observations suggest that major portions of the runoff comes from field roads, for which curve numbers are two to three times greater than those derived from the cropped area.
Footnotes
Keith R. Cooley and Leonard I. Lane are hy-drologists with the Agricultural Research Service, U.S. Department of Agriculture, Boise, Idaho 83705, and Tucson, Arizona 85705, respectively. This article is a contribution from the Northwest Watershed Research Center, ARS, USDA. Initial research was done at the U.S. Water Conservation Laboratory, Phoenix, Arizona, and the Southwest Rangeland Watershed Research Center, Tucson, Arizona.
- Copyright 1982 by the Soil and Water Conservation Society
