Quoted from: https://epicapex.tamu.edu/apex/
A watershed can be subdivided as much as necessary to assure that each subarea is relatively homogeneous in terms of soil, land use, management, and weather. APEX was constructed to evaluate various land management strategies considering sustainability, erosion (wind, sheet, and channel), economics, water supply and quality, soil quality, plant competition, weather, and pests.
The routing of water, sediment, nutrient, and pesticide capabilities are some of the most comprehensive available in current landscape-scale models and can be simulated between subareas and channel systems within the model.
APEX can perform long-term continuous simulations for modeling the impacts of different nutrient management practices, tillage operations, conservation practices, alternative cropping systems, and other management practices on surface runoff and losses of sediment, nutrients, and other pollutant indicators. Example applications include:
- evaluate effects of global climate and carbon dioxide changes on crop yields
- assess alternative manure applications and other management scenarios
- design biomass production for energy
- demonstrate hydrologic balance components and pollutant transport for different cropping and forestry production systems
- simulate intensive rotational grazing scenarios depicting movement of livestock between paddocks
- evaluate the effects of different tree harvesting treatments on forested watersheds
- analyze the potential benefits of “woody draws” (relatively small, natural drainage areas covered by trees or shrubs in agricultural landscapes)
- determine cropping and conservation practice effects on lake systems
- simulate landscape management decisions such as harvest unit size, total area harvested, and rotation length
- assess environmental impact of pollutants into lakes
- evaluate effects of buffer strips
- simulate nonpoint-source pollution impacts from cultivated cropland
- design economical and environmentally safe landfill sites