Garden with Insight v1.0 Help: Introduction to EPIC model documentation

The Erosion-Productivity Impact Calculator (EPIC) (Williams et al., 1984) model was developed to assess the effect of soil erosion on soil productivity. It was used for that purpose as part of the 1985 RCA (1977 Soil and Water Resources Conservation Act) analysis. Since the RCA application, the model has been expanded and refined to allow simulation of many processes important in agricultural management (Sharpley and Williams, 1990).

EPIC is a continuous simulation model that can be used to determine the effect of management strategies on agricultural production and soil and water resources. The drainage area considered by EPIC is generally a field-sized area, up to 100 ha (weather, soils, and management systems are assumed to be homogeneous). The major components in EPIC are weather simualation, hydrology, erosion- sedimentation, nutrient cycling, pesticide fate, plant growth, soil temperature, tillage, economics, and plant environment control.

Recently, most of the EPIC model development has been focused on problems involving water quality and global climate/CO2 change. Example additions include the GLEAMS (Leonard et al., 1987) pesticide fate component, nitrification and volatilization submodels, a new more physically based wind erosion component, optional SCS technology for estimating peak runoff rates, newly developed sediment yield equations, and mechanisms for simulating CO2 effects on crop growth and water use. These and other less significant developments extend EPIC's capabilities to deal with a wide variety of agricultural management problems.

Example applications include: (1) 1985 RCA analysis; (2) 1988 drought assessment; (3) soil loss tolerance tool; (4) Australian sugarcane model (AUSCANE); (5) pine tree growth simulator; (6) global climate change analysis (effect of CO2, temperature, and precipitation change on runoff and crop yield); (7) farm level planning; (8) five-nation EEC assessment of environmental/agricultural policy alternatives; (9) Argentine assessment of erosion/productivity; (10) USDA-Water Quality Demonstration Project Evaluation; (11) N leaching index national analysis.