Evaluation of the quality and self purification potential of tajan river using qual2e model
Industrial development accompanied by population and consumption growth has imposed heavy pollution loads to natural resources. Regarding finite origin of such resources, maintenance and monitoring of current ones must be thoroughly considered. Water is among the most significant resources that must be preserved. This fact is more highlighted when we consider that Iran with current population growth is anticipated to be involved with water crisis by the year 2025. Rivers are considered as the main water suppliers for human uses. Discharging organic and inorganic pollutants as well as nutrients are contributed as major causes of river water quality deterioration. Selfpurification potential is a capability by which rivers are enabled to dilute, lessen or eliminate the undesirable effects of entered pollutants. Precise specification of such capability may be considered as a powerful instrument in rivers sustainable management. Meandering through Sari County in northern Iran, Tajan River is among significant rivers of Caspian Sea water basin. This river originates from Hezarjarib and Poshtcouh mountains and is comprised from three main streams of Tajan, Zaromroud and Sefidroud. At the beginning of its path, Tajan River undergoes a mountainous gravel bed, while by approaching towards the estuary it flows over the sandy bed of northern Iran plains. The average flow of this permanent river is around 20 m3 per second. Specific studies aimed to correlate the source apportionment of point and non point sources to the observed load of a certain river are still quite scarce (Behrendt, 1999). However, many studies have shown that the estimated nutrient emissions can be much higher than the observed load (Behrendt, 1996, Behrendt and Bachor, 1998, Zessner and Kroiss, 1999, Svendsen and Kronvang, 1993 and Arheimer and Brandt, 1998).