American Journal of Geophysics, Geochemistry and Geosystems Vol. 2, No. 3, 2016, pp. 23-30 http://www.aiscience.org/journal/aj3g ISSN: 2381-7143 (Print); ISSN: 2381-7151 (Online) * Corresponding author E-mail address: drebadati@iiau.ac.ir Role of Geological Structures and Lithology in the Quantitative and Qualitative Changes of Takestan Aquifer Naser Ebadati * Geology Department, Science Faculty, Islamshahr Branch, Islamic Azad University, Islamshahr, Iran Abstract Takestan region constitutes part of the feeding and underground waters intake to Qazvin plain aquifer and such waters gradually change quantitatively and qualitatively through time along the path. The aim of this study is determining the interactive effects of water sources and geological structures, lithology and the resulting qualitative changes as well as evaluating the role of structural factors in quantitative changes of the area water sources. For this purpose, to assess the underground water sources and range of groundwater tables the existing 144 exploratory boreholes in the understudy area range were used and physical and chemical analyses were performed through sampling from the wells in 5 station and the changes in anions, cations, TDS, EC and TH values for either one of the parts were obtained. Based on the results of surface waters and groundwater tables' quality analysis as well as examining the geological maps, this paper deals with the analyzing of the relationship between water features and structural-geological changes of the under study area. There is a significant relationship between lithology features, structural geology of the basin and quantitative-qualitative changes of water sources in the area. Keywords Takestan, Aquifer, Hydrogeology, Quality Changes Received: June 5, 2016 / Accepted: June 14, 2016 / Published online: July 27, 2016 @ 2016 The Authors. Published by American Institute of Science. This Open Access article is under the CC BY license. http://creativecommons.org/licenses/by/4.0/ 1. Introduction In Takestan region (west of Qazvin province) the low precipitation volume and high evaporation in this plain besides more than 50% shortage of precipitation and other adverse hydrogeological conditions has caused the high water and important rivers of the area to stop flow. The exploitation level in the area is higher than the feeding rate and causing falling down of the underground water level and consequently shortage of the water sources' budget in area [1, 5]. Harzandat plain area located adjacent to Takestan and Qazvin plain studied the effect of geological formations on the quality of groundwater sources and concluded that the plain’s underground water table has been constituted from fine particle sediments like silt and clay accompanied by sand and gravel that are materials with law permeability. Therefore this has caused low velocity flow of the underground water and extended retention time of underground water inside the table, ultimately resulting in declining of water quality under the influence of marl lime units and red conglomerates with marl interlayers [3, 4]. Askari (2009) used and geographical information system (GIS) and geo statistical method to study the local changes of the underground water quality of Qazvin plain and proposed