Introduction to complex systems

The water cycle is one of the complex systems which the scientific community is constantly faced. It can be decomposed on the different processes as :

• Precipitation

• Infiltration

• Evaporation

• Retention

• Hydraulic flow

As we can observe from the schematic water cycle represented in the above figure, the listed processes interact each other, for example the rainfall which varies in time and space enters in the sewer system which has a non uniform spatial distribution. So, if we want to model the concentration of a given pollutant by simplistic models at the outlet of the sewer system (or inlet of water bodies) this well not be representative of the reality.