Survey of surface runoff quality in Zahedan for irrigation usage

Background & Aim: Urban runoff is one of the most valuable and renewable water resources in many arid and semi-arid parts of the world. Understanding how to use these resources is very important. The purpose of this study was to determine the physical, chemical and biological properties of surface runoff in Zahedan for irrigation uses. Methods: The present work was a descriptive cross-sectional study. Grap sampling was taken at two rainfall events at the intersection of Azarakhshi and Pasdaran crossings. The samples were examined for physical, chemical and microbial parameters according to the standard water and wastewater testing methods and qualitative irrigation parameters. The results were compared with Iranian and FAO environmental standards for irrigation uses. Results: The mean COD and BOD5 parameters were 359 and 56.6 mg/l, respectively and the mean heavy metals of nickel, zinc, cadmium, lead, copper, chromium, iron in solution were 6.8, 66.66, 1, 2.2, 8.93, 5.1 and 92.5 mg/l, respectively. The mean total coliforms were 38333/33 MPN/100ml. The average of irrigation quality indices including SAR and Na% were 20.1 and 59.2%, respectively. Conclusion: The results showed that the surface runoff of Zahedan in many parameters including heavy metals such as nickel, zinc, lead, copper and chromium, turbidity, TSS, TDS, sodium, total coliform CODs and CODs are above the maximum permitted DOE and FAO limits for irrigation usage.