fuzzy correlation model

The quality of river water is deteriorating due to natural and human impacts. Arvandroud is a common river on the border of Iran and Iraq that irrigates many urban and rural areas and agricultural fields in Abadan and Khorramshahr regions. This research was conducted in 2022 with the aim of determining the quality characteristics of Arundroud water using NSFWQI index and fuzzy association model.

Sampling and measurement of physical, chemical and microbial parameters were done using the standard method and 60 water samples were prepared from 10 stations with 3 replications in spring and summer. The water quality of Arvand River was investigated based on NSFWQI index and fuzzy correlation model.

Fuzzy correlation analysis between the measured values of the parameters in the studied stations showed that the correlation was significant with the increase of the Pearson statistic values (P<0.05). Based on the results of the classical correlation method, only the pH variable showed a significant correlation between the stations under study (P<0.05). Input functions included Pearson correlation and Sig. statistic (2 tails) and the output variable was the fuzzy correlation coefficient. For Sig. (2-tailed), 5 classes as very weak, weak, medium, strong and very strong, for Pearson's statistic 5 classes as very weak, weak, medium, strong and very strong and for phase correlation coefficient 4. The classes were determined as very weak, weak, medium and strong.

According to the final NSFWQI index, the quality of water in all studied stations in Arundrud is at a bad level. By inserting the calculated correlation values in each variable, the results showed that the effect of pollutants on temperature was very weak, pH and total coliform were weak, and nitrate and TSS were moderate and strong for BOD, DO, phosphate and turbidity.