Objective To develop a computer model for hydrologic and contaminant fate analysis of watersheds with subsurface drainage. As plants undergo stress, whether from excess or restricted moisture or excess salinity, plant growth is restricted and yield is often reduced. Drainage is the removal of excess water from the soil.
Water is added by rainfall, irrigation or subsurface groundwater to the crop root zone.
If a high water table or subsurface impermeable layer restricts the downward movement of soil water, then soil waterlogging reduces crop production. In irrigated regions, high water tables lead to salinization of soils. Soil pore space can be occupied by liquid or gas. A favorable soil environment has a balance of water and oxygen in soil pores. Permanent wilting point.