Water Quality Zonation of Beshar River in Yasuj City

Abstract

AbstractThis study was conducted to monitor the current water quality of Beshar River by the Iranian Surface Water Quality Index (IRWQIsc). Monitoring of the river water quality was done based on sampling 12 stations along the river in October of 2021 as the period of water shortage and January of 2022 as the period of high water flow simultaneously with sampling two other stations (fish farm effluent and Yasuj wastewater treatment plant effluent) as the point source pollution entries. The results of zoning Beshar River based on IRWQIsc in the period of water scarcity showed a decrease in river water quality from the upstream to the downstream part. 41.66% of the upstream part of the river (Tang-e Tizab to Dehno) was in a relatively good condition, 8.34% of the river (entrance of Yasuj City) was in a good condition, 8.33% (middle part of the river in Shah Mokhtar Area) was in a relatively bad condition and 41.66% (downstream of the river) was in a moderate condition. Despite the increase in discharge and rainfall, no significant increase in water quality was observed in the high water flow period. In this period, 25% of the river (Tang-e Tizab, Tang-e Sorkh, and downstream of Qalat) was in a moderate condition and 75% of the river was in a relatively good condition based on IRWQIsc. Comparison of the flow rates and IRWQIsc indices showed that only during the high water flow period in the lower reaches of the river, the increased river discharge enhanced the river water quality , but no relationship between the river flow and the IRWQIsc was found at the upstream part of the river and in the period of water scarcity.Keywords: Beshar River, IRWQIsc index, biological oxygen demand IntroductionWater quantity and quality are of the most vital parts of each ecosystem that affect other parts. Therefore, evaluation of the quantity and quality of river water can indicate the status of water resources management in a watershed. Beshar River is one of the most important and water-rich rivers in Kohgiluyeh and Boyer-Ahmad Province. It provides most of the water needed for drinking, industry, and agriculture, while being exposed to various pollutions. This study was conducted to monitor the current water quality of Beshar River by the Iranian Surface Water Quality Index (IRWQIsc). MethodologyMonitoring of river water quality was done based on sampling 12 stations along the river from the upstream (Tang-e Tizab) to the downstream (Pataveh) parts in October of 2021 as the period of water shortage and January of 2022 as the period of high water flow simultaneously with sampling two other stations (fish farm effluent and Yasuj wastewater treatment plant effluent) as the point source pollution entries. DiscussionThe results of zoning Beshar River based on IRWQIsc in the period of water scarcity showed a decrease in the river water quality from the upstream to the downstream part. 41.66% of the river (upstream part of the river, Tang-e Tizab to Dehno) was in a relatively good condition, 8.34% of the river (entrance of Yasuj City) was in a good condition, 8.33% (middle part of the river in Shah Mokhtar Area) was in a relatively bad condition, and 41.66% (downstream of the river, Tange-Seriz to Pataveh) was in a moderate condition. Despite the increase in discharge and rainfall, no significant increase in water quality was observed in the high water flow period. In this period, 25% of the river (Tang-e Tizab, Tang-e Sorkh, and downstream part of Qalat) was in a moderate condition and 75% of it (Qalat, Dehno, entrance of Yasuj City, Shah Mokhtar to Pataveh) was in a relatively good condition based on IRWQIsc. ConclusionComparison of the flow rates and IRWQIsc indices showed that the increased river discharge in the lower reaches of the river increased the river water quality only during the high water flow period, but at the upstream part of the river and in the period of water scarcity, no relationship was seen between the river flow and IRWQIsc. Proper exploitation of Tang-e Sorkh Dam upstream of Bashar River in the near future and determining and supplying the environmental flows of the river with regard to water quality, especially at its upstream part should be taken into consideration to keep the self-purification ability of the river. References- Abdullah, N. and Jain, S. (2020). Multi-index summer flow regime characterization to inform environmental flow contexts, A New England case study. Ecological Indicators (111):15-1.- Kareem, S., Jaber, W., Al-Maliki, L., Al-Husseiny, R., Al-Mamoori, S. and Alansari, N. (2021). Water quality assessment and phosphorus effect using water quality indices: Euphrates River- Iraq as a case study. Groundwater for Sustainable Development (14): 1-10.- Marselina, M.; Wibowo, F. and Mushfiroh, A. 2022. Water quality index assessment methods for surface water: A case study of the Citarum River in Indonesia. Heliyon (8): 1-10.- Matta, G.; Nayak, A.; and Kumar, A. (2020). Water quality assessment using NSFWQI, OIP and multivariate techniques of Ganga River system, Uttarakhand, India. Applied Water Science 10: 1-12.- Murali, K.; Meenakshi, M. and Uma, R. N. (2020). Surface water (wetlands) quality assessment in Coimbatore (India) based on national sanitation foundation water quality index (NSF WQI). 1st International Conference on Science, Engineering and Technology: 1-7.- Nemati Varnosfaderany, M., Mirghaffary, N., Ebrahimi, E., and Sofyanian, A.R. (2009). Water quality assessment in an arid region using a water quality index. Journal of Water Science & Technology (60.9): 2319-2327. Figures and Tables- Fig. 1: Study area of Beshar River with locations of the point sources of pollution- Fig. 2: Study area and locations of the sample stations along Beshar River- Table 2: IRWQIsc indices and their weights (Water Resources Quality Index, 2013)- Table 4: Classification of surface water qualities of Iran based on IRWQIsc (Water Resources Quality)- Table 5: The measured variables of water quality for the sample stations along Beshar River during the low water flow period- Table 6: The measured variables of water quality in the sample stations along Beshar River during the high water flow period- Fig. 3: IRWQIsc index of the sample stations along Beshar River and effluents of the major sources of pollutants- Fig. 4: Changes of IRWQIsc indices along Beshar River during the high and low water flow periods- Fig. 5: The relationship between discharge and IRWQIsc index in the studied stations (numbers of the stations from the upstream to the downstream part of Beshar River from 1 to 12, respectively)- Supplementary Table 1: Locations of the sample stations along Beshar River and their water qualities- Supplementary Table 2: Water quality variables and their measuring methods (Rezvanipour and Razavi Dinani, 2014)

Keywords

• beshar river
• irwqisc index
• biological oxygen demand