ABSTRACT
Models of water flow and transport predict changes in conservative properties or the change in state of the system that results from a change in one or more of its intrinsic properties: energy, mass, or momentum. Relating contaminants to sources is an integral part of establishing cause-and-effect relationships between sources of impurities, and the effects on water quality. The fundamental mechanistic principles for all modem models of flow and water quality are based are the laws of conservation, familiar to any student of physics and mechanics. The basic equations for fluid motion and transport consist of conservation equations for water mass, momentum, thermal energy, and constituent mass. One of the best ways to understand the effect of turbulent motion is to observe rising smoke plumes. The scales of interest in water quality modeling vary over many orders of magnitude in time and space depending on the particular problem and setting.
