The volume of water entering the pond or wetland on a given day is calculated:
8:1.2.8
where is the volume of water flowing into the water body on a given day (m HO), is the fraction of the subbasin area draining into the impoundment, is the surface runoff from the subbasin on a given day (mm HO), is the groundwater flow generated in a subbasin on a given day (mm HO), is the lateral flow generated in a subbasin on a given day (mm HO), is the subbasin area (ha), and is the surface area of the water body (ha). The volume of water entering the pond or wetland is subtracted from the surface runoff, lateral flow and groundwater loadings to the main channel.