AnnAGNPS Pollutant Loading Model
The irrigation module determines each day if an irrigation event takes place. If so, the depth of water applied is calculated as well as a first estimate of runoff (later revised in Soil_Moisture) and the net amount of water entering the soil. Several types of furrow, sprinkler, and other irrigation methods are considered as well as three types of scheduling: automatic, which is triggered by soil moisture falling below a threshold; manual interval, where a specified amount of water is applied on a regular schedule; and manual irrigation on irregularly spaced dates. The occurrence of chemical irrigation is also tracked.