The rivers rejuvenate themselves by traveling over a distance thereby they assimilate the pollution load and cause their own self-cleansing, also termed ‘Self-purification capacity’. To ascertain such assimilative capacity of the river system, various water quality models (WQMs) were studied. Out of numerous WQMs, six models including QUAL2Kw, WASP, SWAT, SIMCAT, MIKE-11, and CE-QUAL-W2 were selected and studied on basis of their development, characteristics, capabilities and strengths, model input, governing equations, application, assumptions and limitations. A comparison based on such a study showing input variables and data, assumptions and limitations, strengths, and specific characteristics has been carried out and tabulated. While the selection of a model is based on the problem for which the decision-making is to be done. Of all the models, QUAL2Kw and WASP have been found to be advantageous over the rest. For a complex river system, a single model may not work and in such cases, a combination may be tried. A model finally selected for a problem must be calibrated so as to have minimum errors and maximum accuracy.

  • Sustaining river water quality is essential for the entire river ecosystem.

  • The assimilative capacity of the rivers defines its limit to absorb pollution load.

  • Dissolved oxygen (DO) content is a key indicator of the health of the river.

  • Mathematical modeling support in estimation of pollution loads of the river.

  • Water quality models serve as an effective tool in Environmental Impact Assessment.

Graphical Abstract

Graphical Abstract
Graphical Abstract
This content is only available as a PDF.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY 4.0), which permits copying, adaptation and redistribution, provided the original work is properly cited (http://creativecommons.org/licenses/by/4.0/).