Watershed Scale Physically Based Water Flow, Sediment and Nutrient Dynamic Modeling System - Landscape Ecology for Sustainable Environment and Culture - page 160

model has the advantage of being fully distributed and physically based. All
simulation parameters employed have physical or well-established empirical
meaning, and all are within the bounds of published or field measured values. It is
thus concluded that the model could be a powerful tool to investigate and assess
the time-varying hydrology and sediment and nutrient transport and fate of a
watershed. Especially, in agricultural sector, it would absolutely be an invaluable
tool for quantifying water quality impacts by agricultural farming and practices.
However, model physically based formulation will require application on a data
set

that includes detailed rainfall, soil moisture, and distributed source

observations.

Appendix: Water Quality Parameters

concentration of soil layer fresh organic N pool [M/L 3 ]

orgN frs

ON min|imb net mineralization/immobilization rate of soil layer fresh organic N

pool [M/L 2 /T]

decomposition rate of soil layer fresh organic N pool [M/L 2 /T] ON dec

ON frs,e net surface erosion/deposition rate of soil layer fresh organic N pool

[M/L 2 /T]

external sources [M/L 2 /T] ON frs,s

concentration of soil layer active organic N pool [M/L 3 ] orgN act

ON trn rate transferred between the active and stable organic N pools

[M/L 2 /T]

mineralization rate of soil layer active organic N pool [M/L 2 /T]

ON min

ON act,e net surface erosion/deposition rate of soil layer active organic N pool

[M/L 2 /T]

external sources [M/L 2 /T] ON act,s

ON sta,e net surface erosion/deposition rate of soil layer stable organic N pool

[M/L 2 /T]

ON sta,s external sources added to the soil layer stable organic N pool

[M/L 2 /T]

pool [M/L 3 ] NH 4 concentration of soil layer NH 4

NH min total mineralization processes rate of soil layer organic N pools

[M/L 2 /T]

net nitrification/volatilization processes rate in the soil layer [M/L 2 /T]

NH nit|vol

plant uptake rate of soil layer NH 4 pool [M/L 2 /T]

NH up

mass transfer rate of NH 4

R NH4,e between the upper soil layer and surface

runoff [M/L 2 /T]

external sources [M/L 2 /T] NH s

concentration of soil layer NO 3 pool [M/L 3 ]

NO 3

denitrification processes rate in the soil layer [M/L 2 /T] NO dnit

plant uptake rate of soil layer NO 3 pool [M/L 2 /T] NO up