Study on physical, chemical and biological qualities of Chah-Nimeh water reservoirs in Zabol for year 2011

Recently، as human population has been increased quickly، water problems and its distribution have affected water storage in the Third World، especially in arid and semi-arid areas like Sistan. The aim of this study was to investigate water quality of three reservoirs of Chah- Nimeh during different seasons of 1390. This research was done as descriptive-cross sectional for one year on three reservoirs. For water sampling، three stations at inlet، middle and outlet of each reservoir were chosen. The sampling was performed during four seasons of 1390، at the water depths of 10، 20 and 30 cm each at three replicates so that، totally، 324 water samples were taken. Then different water qualities including EC، pH، TDS، DO، TSS، turbidity، salinity، hardness، nitrate، nitrite، phosphate، temperature، coliform، BOD and COD were measured at laboratory. Finally، measured water qualities were assessed according to the universal standards. The results of sampling were compared with the relevant standards of Iran، FAO، WQI and Wilcox regarding to different applications in drinking and agriculture sections. Assessment of the WQI showed that for the studied reservoirs this index was 54، 59 and 58، respectively، indicating moderate drinking water quality. Also، based on the Wilcox index، water quality classified as C2S1 and C3S1. The results also indicated that all the measured parameters except pH، Mg، NO3، Na، BOD، COD and DO showed significant changes (p<0. 05) with season. Also، coliform، Na، turbidity and TSS showed significant differences (p<0. 05) among the studied reservoirs، whereas most of the water quality parameters were in a similar range among the three reservoir. Also، the average coliform in reservoir No. 2 was higher than that of the other two reservoirs which was attributed to the pollution of adjacent area. Assessment of Wilcox Diagram and WQI index showed that all the three reservoirs were classified in moderate condition for agricultural and drinking applications.