Hydrology
hojat miranimoghadam; Gholam Hossein Karami; Rahim Bagheri
Abstract
Gonabad area is an arid region where 19.5 mcm of groundwater is annually extracted from 26 qanats. Six major qanats were sampled for hydrochemical and isotopic analyses to determine the origin and flow mechanism of the groundwater.The total dissolved solids vary from 524 to 2375 mg/l. The dominant water ...
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Gonabad area is an arid region where 19.5 mcm of groundwater is annually extracted from 26 qanats. Six major qanats were sampled for hydrochemical and isotopic analyses to determine the origin and flow mechanism of the groundwater.The total dissolved solids vary from 524 to 2375 mg/l. The dominant water types are Na+-Mg2+-HCO3- and Na+-Cl-. The groundwater is saturated with regard to carbonate minerals and under-saturated with regard to evaporate minerals. This means that the composition of the groundwater is highly controlled by the dissolution of carbonate rocks. The deuterium and oxygen 18 isotopes signatures demonstrate the meteoric origin of the groundwater and the flow mechanism is direct infiltration of precipitation before evaporation through fractures in the limestone formations and infiltration of surface water in the coarse grain alluvial cones at the south of the plain. The groundwater recharge originates from an area between 2000 to 2700 m a.s.l. The groundwater of these qanats has depleted stable isotopes in the wet season due to recharge through the infiltration of precipitation and has enriched stable isotopes in the dry season due to recharge through the return flow of qanats and springs used for agricultural activities in the south of the basin.
Hydrology
A. Shemshaki; Gh. H. Karami
Abstract
The water level of Urmia lake during the last twenty years has been significantly declining. Along with changes in quantity, water quality has also substantially changed. In this article, attempts has been made to identify the relationship between water quality and quantity to have a better understanding ...
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The water level of Urmia lake during the last twenty years has been significantly declining. Along with changes in quantity, water quality has also substantially changed. In this article, attempts has been made to identify the relationship between water quality and quantity to have a better understanding of the changing history of the lake during the geological past. This can help to better explore the risk factors influencing the drying process of the lake. This understanding can therefore be employed to appropriate planning and management procedures in order to revive this lake effectively. Based on this study, the lake water in the levels higher than 1286 meters (MSL) is brackish to fresh and is not of saline type. Thus, it seems that, in the late Pleistocene, the lake water was of a fresh type where the water level was higher than 1297 meters. The study revealed that the lake become to a playa-type environment in water level of about 1273 MSL. The present water level of 1270 meters suggests that the lake has a dominantly playa-type environment. In this environment, increase in precipitation and inflows will lead to a rapid increase in reservoir volume; and vice versa, a stop or decrease in the precipitation and inflows with an increase of temperature and evaporation will lead to a rapid reduction in reservoir volume. This study estimates that a volume of over 9.5 billion cubic meters of water is necessary to revive the Urmia Lake.
