Enrichment Ratio
Last updated
Last updated
The enrichment ratio is defined as the ratio of the concentration of phosphorus transported with the sediment to the concentration of phosphorus in the soil surface layer. SWAT+ will calculate an enrichment ratio for each storm event, or allow the user to define a particular enrichment ratio for phosphorus attached to sediment that is used for all storms during the simulation. To calculate the enrichment ratio, SWAT+ uses a relationship described by Menzel (1980) in which the enrichment ratio is logarithmically related to sediment concentration. The equation used to calculate the phosphorus enrichment ratio, , for each storm event is:
4:2.4.3
where is the concentration of sediment in surface runoff (Mg /m HO). The concentration of sediment in surface runoff is calculated:
4:2.4.4
where is the sediment yield on a given day (metric tons), is the HRU area (ha), and is the amount of surface runoff on a given day (mm HO).
Table 4:2-4: SWAT+ input variables that pertain to loading of P attached to sediment.
Variable Name | Definition | Input File |
---|---|---|
SOL_BD
: Bulk density(Mg/m)
.sol
ERORGP
: Phosphorus enrichment ratio
.hru