Site-specific risk assessment and management of point and diffuse sources - Environmental Deterioration and Contamination: Problems and their Management - page 343

Figure 10.6 Water balance of a watershed: percentage distribution of the annual precipitation between
runoff (20-50%), infiltrated (10-60%), evaporated (10-20%) and transpired (10-50%)

waters.

experiments using the materials from the source area may provide useful information.
The steps of diffuse pollution assessment and management are:

1 Sources diffuse → estimating/modeling → E source → C runoff → GIS modeling →

PEC river

2 PEC river > EQC river → target → pec river ≤ EQC river

3 E diffusesource → risk reduction by emission mitigation → e diffusesource ,

where:

- E : emission from diffuse sources;
- C : concentration;
- GIS modeling: GIS-based hydrological modeling.

- PEC : predicted environmental concentration;

- outflow from the watershed in the black box;

- EQC : environmental quality criterion;
- Capital letter: high concentration, unacceptable value;
- Lower case: low concentration, acceptable and targeted value;
-“

river =

→ '': next step.

4.2.2 Model calibration using the RRR rate of the watershed

The transport pathway between the diffuse sources and the compliance point in a
watershed is considered as a “black box'' within which the flux and concentration of the