Investigation of Destructive Effects and Environmental Solutions of Sand and Gravel Extraction from Urmia Nazlouchay River

Excessive extraction of sand and gravel from the riverbeds entails many environmental problems. In this paper,the destructive environmental consequences of inordinate extraction of sand and gravel from the bed of the Nazlouchay river is investigated. Qualitative study and physical and chemical analysis of water of the Nazlouchay river at two sampling stations indicate the negative effect of sand and gravel mining activities, so that by increasing the amount of suspended particles from 20to98milligrams per liter,the amount of total solid suspended particles is quintupled, and consequently, the water turbidity in the second station has increased 14times. Excessive turbidity of the water of the Nazlouchay river and sedimentation of sludge in the lower bed as well as the instability of the riverbed due to sand and gravel extraction has caused the population of aquatic plants such as algae and macrophytes decrease sharply. even reach the brink of extinction. Other environmental consequences include: reduced quality of recreational, sportive, touristic landscape of the Nazlouchay river, bed erosion and river shore, and many other factors. Nowadays, the sand washing plant of the Nazlouchay with 1,800tons of daily feed consumes more than 1,650cubicmeters of fresh water,and produces about 1,500tons of screened sand and gravel. The wastewater of this sand washing plant with a solid content of about 10-15% is discharged into one of the extraction points site of the material as a tailings pond and sediment barrier.If the plant uses a Thickener system for water recycling by dewatering of its wastewater,the solid content of the waste output will be around 45%and the water consumption will be about 450cubicmeters, which will decrease to 27%of current water consumption. Also, if the paste tailing system is used in this plant, the water consumption will be only about 220cubic meters per day, which is only 13% of current water consumption.