Watershed Scale Physically Based Water Flow, Sediment and Nutrient Dynamic Modeling System - Landscape Ecology for Sustainable Environment and Culture - page 150

Table 8.5 Mathematical expressions for overland flow phosphorus transformations

P species P transformation equation

Particulate organic P (POP)

@ POP ov
@ t

¼ L ð POP ov Þ k hp POP ov

Dissolved organic P (DOP)

@ DOP ov
@ t

¼ L ð DOP ov Þþ k hp POP ov h DOP ov k mp DOP ov

Dissolved inorganic P (DIP)

@ DIP ov
@ t

¼ L ð DIP ov Þþ k mp DOP ov h DIP ov R DIP ; up

Fig. 8.3 Schematic representation of GSSHA in-stream water quality modeling

8.3.3 In-Stream Water Quality

For in-stream water quality modeling it is assumed that longitudinal and temporal
changes (1D transport) are applicable. Water quality is affected in streams due to
physical transport and exchange processes and biological, chemical, and bio-
chemical kinetic processes along with changes due to benthic sediments. Cur-
rently, the in-stream water quality module includes a set of nutrient simulation
kinetics. In-stream water quality kinetics computes algal biomass, organic and
inorganic nitrogen and phosphorus species, CBOD and DO. The schematic rep-
resentation of GSSHA in-stream water quality processes is shown Fig. 8.3 .
The nutrient transport and transformation equations in the water column are
summarized in Table 8.6 .