An Investigation of Qualitative and Quantitative Characterization of Groundwater: A Case Study of Ghaen, Eastern Iran

Ghaen Plain which is located in southern Khorasan province has arid and semiarid climate. An investigation of the piezometer, depth and hydrographic maps shows the long-term decline in the groundwater level by 0.5 meters per year. An investigation of hydrograph for the last 8 years has shown that the groundwater level had a 5/3-meter decline which is less than the long-term decline in most basins. In order to assess the quality of groundwater, electrical conductivity (EC), chlorine and total dissolved solid (TDS) were analyzed. Then, the trend of changes of these variables was analyzed over time. The increase in these variables with weather changes reduced recharge and uncontrolled exploitation which have caused a decline in groundwater levels and bad quality. Low levels of TDS, EC and Cl from north to south are indicative of the presence of possible layers of gypsum and salt in the north. Their presence in the northeast (Out watershed) is due to water movement from the recharge to the discharge area and mixing of the waters of the southern and the northern parts.