پژوهشهای آبخیزداری (Dec 2022)
Evaluation of the Intrusion Extent of Maharlu Lake Saline Water into the Maharlu Coastal Aquifer Using Hydrochemical Parameters
Abstract
The management of freshwater resources in the coastal aquifers of salt lakes requires understanding the dynamics of the flow system, geochemical evolution, etc. The salinity of coastal aquifers is mainly due to direct saltwater intrusion, or is associated with complex geochemical interaction of lake and Ground water. The purpose of this study is to investigate the extent of intrusion and entry of saline water of Maharlu Lake into the coastal aquifer of the Maharlu aquifer, employing hydrochemical parameters and delineating the chemical evolution of its groundwater. The information used in this study includes the water level fluctuations and spatial, depth, and temporal changes in water salinity, and the chemical composition of the aquifer groundwater. For this purpose, several methods including water table maps and salinity changes, diagram of hydrochemical evolution of water, Stiff diagram, and chloride to bromide ions ratio have been used. According to the results obtained in the whole study period (February 1997 to February 1998), the water table elevation of a large area of the aquifer is lower than the elevation of the lake floor and, therefore, the Lake saline water flows into the aquifer under the reverse hydraulic gradient. Hence, in addition to the normal phenomenon of saline water intrusion, which occurs due to density gradients, aquifer salinization is also strongly influenced by the entry of saline water under the influence of hydraulic gradients. Based on the results of this study, the aquifer in terms of salinity and the effect of the Lake water on its salinity is subdivided into three zones, including; an area that starts from the lake margin up to a maximum distance of 1000 meters, which is completely affected by the entry of saline lake water, an area starts from 1000 meters to about 1500 meters as a middle area affected by both phenomena and the area from 1500 meters to about 2200 meters, located in the foothills of the southern karst boundary, the alluvial feeding area of the aquifer, which it's water quality is relatively suitable for agriculture.
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