The fertile plain of Shabestar is located 40km. west of Tabriz and northeast of Urumiyeh lake and its area is about 617 km^2. Shabestar plain is an active cultivated area with low annual precipitation and surface runoff thus. the groundwater resources have a vital role in supplying agricultural drinking domestic and industrial water demands. Saline water intrusion into the fresh water aquifers is highly increased in recent years and some of abstraction wells are left unused. The purpose of this paper was to determine origin of the water salinity in the plain. Therefore from the previous hydro-geological data and several number of sampling from the plain wells two groups of saline water were distinguished. Group 1 contain the low ratios of S04/Cl and Na/Cl and high percent of Ca + Mg. Saline water of the central parts of the plain lies in this group. Group2 contain the high ratios of SO__4/Cl and Na/Cl and low percent of Ca+Mg. Saline water of the southeast and south margin of the plain lies in this group. In the central parts ratios of SO__4 and Cl to the sum of anions are similar to those of the Urumiyeh Lake. Consequently saline water source in these parts can be related to Urumiyeh Lake. However in the southeast and south margin of the plain ratios of SO4 and Cl to the sum of anions are different from those of the Urumiyeh Lake. Evaporation from the shallow groundwater seepage from saline rivers and dissolution of the evaporational deposits are causes of the salinity.

Rudbar Lorestan Dam and Power Plant locates on the High Zagros structural zone, according to the geological map of Iran. The Dalan Formation, Permian age, forms the geological structure of dam body foundation and a portion of its reservoir. Meanwhile, outcrops of an Upper Cretaceous formation, called Sarvak Formation, are exposed out beside the Dalan Formation, due to effect of thrust faults. The main sources of Rudbar Lorestan river are precipitation and drainage of groundwater. The karstification process in carbonate sediments at the site was expected to be expanded well, due to geological and climate conditions. However, based on the evidences of karstic features, which could make a drainage network, have not seen. Both confined and unconfined aquifers present in the site. In this regard, presence of artesian boreholes is a good evidence for confined aquifer. The dominant types of ground water are calcic bicarbonate and sulfate, based on chemical analysis of 22 samples, collected from six sources of water at the site, In this manner, the types of water of the Rudbar river, Kish spring and outlet of access tunnel T2 are calcic bicarbonate, because of recharge from unconfined aquifers and short residence time. However, the type of water of artesian boreholes, i.e. TG-4 and RB-8, and inlet of the access tunnel T2, are calcic sulfate, based on contact of water with sulfate minerals and long residence time in confined aquifers.

Geological, mining, agricultural and industrial activities may be the origins of introducing toxic materials into the ecosystem. If traces of toxic elements are introduced three times the permitted doze into human’s body through geochemical circulation, it can be hazardous in the long run. In this research, the adverse effects of alteration zones on groundwater quality have been investigated in Tarom Range, Iran. Surface and groundwater water samples (from alteration zones and various as well as from rock types were taken from the study area. The samples were analyzed for pH, TDS, main cations and anions, as well as for trace elements. The hydro geochemical data were also analyzed using multivariate analysis of cluster and discriminate analyses. The results indicate that the naturally contaminated water can be separated from fresh water using multivariate analysis. The water quality groups resulting from multivariate analysis were evaluated using Stiff, Piper and Wilcox diagrams. Such quality water bears a sour taste; it is dangerous and particularly very dangerous if used for drinking; it as well as seriously harmful to plants if used for irrigation.

Gorgan Plain with an area more than 5000 km2 is located in the southeast of Caspian Sea. Since groundwater is the major source of water for domestic, industrial and agricultural uses in the area, it is necessary to ensure groundwater quality by protecting them against pollution sources. In this study, hydro geochemical data from 96 irrigation wells were used to evaluate water quality and to determine processes that control water chemistry. The samples were classified into five groups (I, II, III, IV and V) according to their geochemical characteristics using cluster analysis. The results indicate that the groundwater quality and geochemical characteristics of clustered samples are consistent with the geology and hydrography of the area. Samples collected from the area close to the recharge points which had been covered with gravels and sands were clustered into group I. The amounts of parameters such as pH and TDS as well as the concentration of HCO3 and SO4 in area which had been covered by silty soils were higher as distance from the recharge points increased (groups II and III). The highest concentrations of chlorine and sulfate belong to the northern parts of the study area (groups IV and V), which is mainly covered by fine grain sediments of clay. Spatial distribution of the statistical groups showed that the samples from each group are in close proximity to one another suggesting the same processes and/or flow paths. Overall, the results showed that groundwater clustering based on water chemistry could be applied to the contamination susceptibility assessment for ground waters in different areas.