Soil conservation service curve number

The water recharge for the Maui fields was calculated with a simple hydrologic balance for each field using rainfall data from nearby rain gauges. Both fields were non-irrigated. A rainfall-runoff relationship was developed for each field using the USDA-Soil Conservation Service "curve number" approach. The validity of this approach for Hawaii conditions was demonstrated by Cooley and Lane (20). Potential evapotranspiration from pineapple fields was assumed to be one-third of pan evaporation throughout the study period, based on results of Ekern (21). but actual ET was adjusted for the water input for each month (3 ). 

CN2 Initial Soil Conservation Service (SCS) runoff curve number for moisture condition II. The SCS curve number is a function of the soil s permeability, land use and antecedent soil water conditions. 

Precipitation in the HELP model is separated into surface runoff and infiltration based on an empirical approach using a modification of the Soil Conservation Service (SCS) mnoff curve number method. Evaporation and transpiration removes water only from the evaporative zone of the cover in the HELP model. The procedure for determining evaporation and transpiration also is empirical. Further details on the procedures and assumptions used in the HELP model are provided by Khire et al. (1997). 

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