تاثير گسترش شهري بر كيفيت آب زيرزميني زاهدان

Urbanization Effect on Groundwater Quality of Zahedan Aquifer

This paper investigates the impact of urbanization on groundwater quality of Zahedan aquifer which, is the sole source of water supply for Zahedan city. The research is based on the collection of available data, field investigation as well as laboratory analysis of groundwater samples. The investigation reveals that phoshours (as P) concentration of groundwater has increased within the urban area owing to conduction of domestic sewage into the absorbing well. The urbanization effect in some has increased the phosphours form an average of 0.02 mg/I to even 0.1 mg/l. Within the urban area the nitrate concentration has increased much above the admissible level, so that in some places it has reached to about 300 mg/I. The high concentration of ammonium and nitrite in some wells are an indication of recent contamination of groundwater by domestic sewage. This research reveals that owing to poor well design and / or construction, 33% of the groundwater samples are positive for total coliform and 11% of the samples shows faecal contamination. The bacteriological contamination varies with changes of depth of groundwater level. In general it can be said that unplanned growth of urbanization has caused a wide range of pollution of groundwater this situation is a warning to the authority to impose a restricted management for urban development and water resources contamination protection.