Shannon’s Entropy Evaluation on Determination of Surface Water Quality, Case Studies: Karun and Babolrood Rivers

The main purpose of this paper is to investigate the Shannon’s Entropy in surface water quality evaluation. To achieve this aim, the Shannon’s entropy and the World Health Organization methods have been used to assign weights of the water quality parameters. Monthly hydrometric data including; Ca, Mg, HCO3, Na, SO4, EC, pH, TDS were analyzed, form 1968-2015, which were measured and recorded at Ahwaz, Darkhovein, Gotvand and Molasani stations of Karun River and as well as; Quran-Talar and Koshtargah hydrometric statins of Babolrood River. The above mentioned rivers are flowing in south and north of IRAN, respectively. The result demonstrated the accuracy of the Shannon’s Entropy performance. As the result showed, the Shannon’s Entropy result gave an encouraging level of agreement with the WHO’s result. However, there were small discrepancies between these two results. Shannon’s entropy weights and the effective parameters of Karun River water quality at different hydrometric stations are Ahwaz pH=0.15, Darkhovein TDS=0.11, Gotvand EC=0.13 and Molasani pH=0.15, respectively, and in a same way for Babolrood River at stations; Quran-Talar pH=0.15 and Koshtargah TDS=0.14, respectively. According to the water quality index values of Karun River, its waters are classified in both excellent and good conditions. However, based on the mentioned values the Babolrood River is classified in excellent condition.