Study the wastewaters effects of the pisciculture ponds in Nurali region on dissolved oxygen of Gorgor River and proposition of solution to management of pisciculture ponds wastewater

This study carried out in 2013 to investigate the effects of wastewaters output of 1500 pisciculture ponds with an area of ​​2,000 hectares in region of Noor Ali (rural areas of central township shushtar in Khozestan province), which totally had 23 Large drains of discharging wastewater, on characteristics and quality of Gorgor river water located between the city of Shooshtar and Ghir dam (at 55 km from the North of Ahvaz). The qualitative and quantitative data were extracted and examined after identifying all major pollutant sources. Reducing dissolved oxygen curve from 7.07 Mg/L to 3.27 Mg /L represented that the water pollution due to the wastewaters of pisciculture ponds into the Gorgor River and the gradual rise of dissolved oxygen to the value of 4.03 Mg/L in the river downstream suggested the river self-refinement and showed that the reduction of pollution load. In general, the effects of pisciculture ponds wastewaters on the quality of the river were quite evident at different intervals, and the minimum critical time (tc), the critical depletion of oxygen (Dc) and its place at the downstream of the discharge point (X) were obtained as 2.64 d, 5.2 mg/L and 45.619 km, respectively. However, according to the river self-refinement capacity in the last station at the downstream, a relatively acceptable quality will be resulted. Finally, the Gorgor River water quality improvement depended on proper management of water waste due to various applications and reduced pollution load.