The Effects of Water Table Decline on the Groundwater Quality in Aquifer of Torbat Jam Plain, Northeast Iran

The prime objective of this research is to study and examine the groundwater decline and its effect on the quality of groundwater in aquifer of Torbat Jam plain for a period of 19 years. Torbat Jam plain stretching over an area of about 3500 km2, in northeastern part of Iran. The plain is considered as a semi-arid to arid zone. It has gained substantial importance because of agricultural prosperity. Almost all water consumption needs are met from groundwater resources. In the last decades, rapid population growth coupled with agricultural expansion has significantly increased demand on groundwater resources. Large increases in water demand with little recharge have strained groundwater resources resulting in declines in water levels and deterioration of groundwater quality in the major parts of the plain. It's worth mentioning th00at the paramount cause of sharp drop in the groundwater table in recent years is conclusively attributed to pumping out of well water which confirmedly exceeds the level of the natural recharge. As a result, the average water level, for instance, has dropped from 1036.47 m to 1002.75 m during the years from 1987 to 2006 with an annual rate of declining about 1.77 m.