The study area encompasses two aquifers namely the Gotvand and Aghili plains located in the north of Khuzestan province and experiences warm and dry climate. The average annual temperature, rainfall and evaporation are 27.6 C, 339.7 and 238.4 mm respectively. The exposed formations are Gachsaran, Mishanm Aghajari, Lahbari member and conglomerate and quaternary sediments. The aim of this investigation was to find out hydraulic connection and virtual hydrochemical interaction between Karun river and the aquifers. For this purpose hydrochemical characteristics of the aquifers in 93-94 and long term hydrochemical changes of the aquifers and Karun river were assessed and no outstanding results was achieved. The main groundwater direction in the Gotvand aquifer was from the northern parts toward central and the northwest and another flow moves toward the south and the east. The groundwater flow in the Aghili aquifer trending from the east toward the west. The Bakhtiari and Gachsaran formations are recharging the aquifers and virtually they feed the Karun river. The hydrograph of both the aquifers depicting decreasing trend. The increase in Cl concentration and Cl/SO4 ratio and decrease in HCO3/Cl ratio in groundwater flow direction, depicting also recharge of Karun river. For hydrochemical assessment from Piper, Drue, Stiff, composite, Scholler, Gibbs and Wilcox diagrams were used. The result indicated that dissolution, deposition and reverse ionic exchange influencing groundwater quality. Factor analysis displayed that lithology and evaporation controlling groundwater salinity

The study area including the Hamidieh and Bostan plains in Azadegan district are located in the southwest of Khuzestan province. The Hamidieh plain is placed between 31° 82´ to 31° 74 ´ latitude and 48 ° 01 to 48 ° 72 ' longitude while the Bostan plain is situated between 31° 72 ´ latitude and 47° 98´ longitude. The average annual evaporation, rainfall, relative humidity and temperature are 32133.8mm, 280mm, 57 percent, 26° C respectively and the climate is desertic dry. The exposed formations are Gachsaran, Mishan, Aghajari, Bakhtiari and Lahbari member. In both the smoothly alluvial plains, scattered sand dunes hills are observed and Karun and Karkheh rivers and also tributaries of Karkheh river are flowing in the area. The collected information from 55 existing piezometers were used to assess hydrostratigraphic units and hydrogeological condition of the area and to draw underground transverse section. The gathered data indicated that underground sediments are dominantly clay, silt, fine grain sand, clayey silt and sand silt. The iso-depth maps displayed that depth to water table ranges between 0.12 to 20 m and 0.74 to 35 m in the Hamidieh and the Bostan plains respectively. The bed rock map depicted alluvial thickness variation between 18 to 88 m and towards the southeast the bed rock depth were increasing. With respect to lithological investigation, piezometers logs and water table fluctuation during piezometers exaction, it was realized that dominant aquifers in both the plains are semi-confined and water table aquifers occupy only a small part of the area. The unit hydrographs of the plains indicated that minimum and maximum water table are in autumn and winter respectively. The main trend of groundwater flow is from the north and northeast to the south and southeast. The piezometers log data were used to estimate hydraulic conductivity and specific yield and their values vary between 0.98 to 15.2 and 8 to 17 percent respectively.

 The Bostan plain is located about 80 km in the west of Ahwaz City. The area is 499 square kilometers, and placed between 31 degrees 56 minutes and 31 degrees 34 minutes north latitude and 47 degrees 54 minutes 48 degrees and 14 minutes east. The studied area is a part of the Khuzestan plain and experiences low altitude; its notable heights are sandy hills and low altitude mountains in the northeast called Mishdadgh. The fllowing rivers in the area are Karkheh, Hohefel and Sableh. The average annual precipitation, annual evaporation (according to the Trent White method), and the average annual temperature are respectively 228 mm, 2701 mm and 26 ° C. According to the climatic indices of Domartan and Sylaninov, the climate of the study area is dry and desert. The chemical properties of groundwater in the Bostan plain synclinal basin are influenced by the composition of deposited sediments, evapotranspiration, topography of the region, and the composition of water supply. Hydrochemical analyzes of 35 water samples during in dry season (July 1395) and wet season (April 2012) have been used to identify the main factors governing geochemical processes of surface and groundwater resources of the the Bostan plain. In this research, two multivariate statistical methods of hierarchical cluster analysis (HCA) and principal components analysis (PCA) were used to classify water quality samples of the region. Based on HCA interpretation, there are three main hydrochemical facies in the Bostan plains. Facies with higher salinity (group 1: Na-Cl), lower salinity facies (group 2: Ca-Na-SO4-Cl), intermediate facies (group 3: Na-Mg-Cl). According to the principal components analysis (PCA), the first factor reveals 68.2% of the changes and the second and third factors depicting 14.45% and 9.25% of the changes, respectively. The results of the present study clearly demonstrate the usefulness of the multivariate statistical techniques in assessing the hydrochemical characteristics of surface and groundwater. The first factor is known as the factor of salinity due to the high variation of Cl, Na, SO4, Mg ions, EC and TDS. The second and third factors indicate pH and HCO3 respectively, as the most variable factors.
Assessment of piezometers logs and depth to water table of the area depicting that water -rock interaction, nature of sediments and evaporation due to low water table are the main factors influential quality of water resources in the study area. Also, the higher saturation indexes of halite and gypsum minerals (more dissolution of these minerals) than other minerals demonstrate the impact of the Gachsaran and Aghajari formations on groundwater resources in the region.

 The study area(Hamidieh plain) is located about 25 kilometers in the west of Ahvaz City and due to unsuitability of groundwater the water usage for various purposes is limited. The area experiences warm climate and average annual rainfall, temperature and relative annual humidity are respectively 222.3 mm, 25.9 C and 52.59% . The Bakhtiari, Aghajari and Gachsaran formationsand Lahbari member are the main expousured formations in the area and they are influencing groundwater quality.In order to assess chemical quality of water resources of the Hamidieh plain in Tir 95 and Ordibehesht 96, in total 31groundwater samples were collected for major ion analysis and in addition 7 more groundwater samples were collected for trace element analysis. To analyse the collected data the Aq.Qa, Chemistry, PHREEQC and ArcGIS software, were taken into account. The dominant water types in Hamidieh plain are sulfate-calcium and chloride-sodic. The groundwater in the eastern parts of the plain and the areas near to surface water are better in terms of containing salts.In contrast, groundwater in the western part of the area where placed far away from surface recharge sources and in addition fall in the end of flow direction suffers from salininity Majority of the Hamidyeh plain groundwater samples exhibit high EC and overall water quality is poor. The sampling stations located adjacent to surface water and affected by feeding of surface water commonly,reveal ion exchange while sampling points far away from the surface water display reverse ion exchange. In this study, PHREEQC software was used to determine the saturation indexes and the results showed that all samples and majority of the samples were saturated with respect to halite and undersaturation with respect to halite and gypsum respectively. Almost half of the samples were saturated with calcite and dolomite and the other half were unsaturated. Plot of the data on Gibbs diagram indicate that evaporation and water-rock interaction are influencing groundwater quality in the area. The Wilcox diagram shows that with exception of surface water, the water quality of the plain is not suitable for irrigation. The Schuler chart shows that water quality of the plain for drinking purposes fall in category of moderate, inappropriate, totally unpleasant and non-drinkable quality. The statistical analysis of factor analysis shows that two factors including lithology and evaporation governing water salinity of the Hamidieh Plain.

  Abstract
Name: Khodabakhsh Surname: Rakiani
Title: Evaluation of the Arpenah karstic spring watershed using structure and physico –chemical characteristics
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Supervisors: N. Kalantari, Ph.D.
Degree: Master of Science Hydrogeology
University: Shahid Chamran University of Ahvaz
Department: Geology Faculty: GeoScience
Keywords: Arpenah¬ karstic spring, Balance, Tectonic, Sorkhbod anticline, physico –chemical, Monge Reza and Shirgon
Abstract:
The Arpenah karstic spring is one of the important spring in Khuzestan province and located at about 50 and 150 Km in the east of Lali City and in the north east of Ahvaz City respectively , along the Sorkhbod thrust in the south west of the Sorkhbod anticline. The anticline composed of Illam-Sarvak ( Miocene) lime stone and considerably karstified. The spring discharge fluctuation is reasonable and as the ratio of the maximum to minimum is about 27, so it seems that the conduit flow governs the spring discharge. The hydrogeological characteristics of the spring carried out taking into account hydrograph interpretation and water balance in the water year period of 93-94. The collected data display that the average annual discharge of the spring is almost 3.3 m3/s and though, the flow regime is conduit- diffuse, but the dominant flow is conduit. The gathered information including, tectonic, hydrograph and water budget depict that the spring mainly feed from the neighbouring anticlines( Monge Reza and Shirgon), through the underground canals and faults. The hydrogeological behaviour of the spring clearly reflects existence of underground water course and affinity of these anticlines. The physico-chemical results indicate that trend of ions variations and physical parameters are under influence of the recharge waters from the Sorkhbod and the adjoining anticlines, where resulted in to overlap the spring water chemistry. The piper diagram illustrates bicarbonate-calcium as prominent facies. The saturation index value of the samples depicting dissolution state of the host rocks and the ratio of calcium with respect to magnesium ion clarifies predominance of lime stone in compare to dolomite.

 

 Excessive exploitation of the alluvial aquifers and creation of a critical condition in most of the plains, more attention is being paid to karstic water resources. In this study, in order to determine karstic horizons, some karst development criteria such as lithology, altitude, slope, rainfall, temperature, vegetation index, drainage density and applying fuzzy inference system and fuzzy hierarchical analysis, karst development modeling was carried out. The results showed that in fuzzy inference systems method, high and very high developed zones covers 55% of the total area, while in the fuzzy hierarchy method is 26%. For validation of the used weights in fuzzy hierarchical analysis, ±10% and ±5% sensitivity analysis was taken into account. . In addition, by creating a correlation matrix between thematic maps, the methods final output and validation, fuzzy inference method is more correlated with the validation map.

 Though, from the past to the present the karst springs have been taken into account to supply water demands for drinking as well as irrigation, but due to the karstic area characteristics, springs discharge in such horizons are generally impressed by climatic conditions (drought and wet periods), Therefore, to recognize these periods are significant for planning and optimal utilization of water resources. In this study standard precipitation index (SPI), stream flow drought index (SDI) and groundwater resource index (GRI) were computed and compared for a statistical periods from 1383 to 1393. The results suggested 1384-1385 as wet, 1390-1391 as drought, and 1392-1393 as a normal years. In order to recognize the effect of the wet and dry periods on spring discharge, the spring discharge and rainfall amount in these three periods were compared with the average of these two parameters in 10 years statistical period. The results indicated that spring discharge in 1384-1385 increased 61% and 54% respectively as compare to the average and normal years. In contrary, the discharge rate in 1391-1390 year was decreased 46% and 49% respectively as compared with the average and normal years. Therefore, it can be concluded that Bibitalkhone spring was impressed by precipitation changes in the past. According to water chemistry analysis the EC and TH of the spring water are more than the average in drought period but less than the wet period. The value of these hydrochemical parameters in normal years are close to the average of ten years. The data is also depicting that chemical quality of spring water affected by drought and wet periods.

<p>Khooshab anticline is located in the South West of Iran and in North West of Khuzestan province. The area is 180 kilometers of the city of Ahvaz and 50 kilometers North West of the city of Andimeshk and between 32&deg;47' to 33&deg;00' latitude and 48&deg;06' to 48&deg;27' longitude. From tectonic point of view, this anticline is in the north of Balarud faulting zone where located in the simple Zagros folded belt. In this study, in order to understand the relationships between geologic structures and hydrogeology Khooshab anticline, the structural geology of the study area were assessed. According to information, reports and field investigations of the study area revealed that the fractures study area of the basement faults and Balarud faulting zones, and also found that the Balarud faulting zone is a left-lateral strike-slip faulting zone with reverse component. The study of geological structures and hydrogeology showed that Asmari- Shahbazan Formation in Khooshab anticline , has been faulted through sever tectonic forces, and as a result of fracture development the area was subjected to karstification phenomena. The karstification features such as dolines in the altitude of Khooshab anticline and relatively high discharge of Gerdab, Babaseyed and Chapko springs, indicate karstic aquifer development in the region. Survey in the region shows which faults control main flow directions basin and density of dominant joints and fractures in spring's catchment area indicates that these small scale linear patterns are responsible for sub-flow paths. The fractures analysis of the study area shows that, the average opening of the joints is more than 20mm, which represents significance role of these features on water infiltration into the karstic aquifer. The bedding plain dip (about 50 degrees) and widening ( on average 45mm), facilitate water infiltration and transportation into the springs catchment. The collected data also show that the high density of fractures in the catchments of Gerdab, Babaseyed and Chapko springs have generated immediate response to rainfall and high discharge.</p>

The Mayaran (Khoshab Anticline) area is located in the northwest of Khuzestan province and about 50 Km in the northwest of Andimeshek city. This area falls between 32˚ 47' to 33˚ 00' N and 48˚ 06' to 48˚ 27' E. In general, the Asmari limestone is dominantly occupy area and due to severe tectonic activities structural features, such as folds (Khoshab anticline), fault (Balarood fault) and joints and fractures. And so area tectonic situation and morphologic instances can say attribute in Mayaran area inordinate transitional karst class features to the holokarst in karst areas morphologic division. In order to assess the hydrochemical of groundwater in the Mayaran karstic aquifer, water samples were collected from the springs in several stages in 93-94. The spring water samples analysis results, exhibited Mg-Ca+ HCO3 as a predominant facies. Show that bicarbonate variations diagram is in accordance with magnesium and calcium changes and the main controlling factor of these parameters concentration is dissolution of carbonates from the Asmari reservoir rock. Collected data indicate about Gerdab (Mongereh) spring vast watershed area that it has in order to high discharge and permanent to basin domain. Balarood fault that create main fault be in anticline, attribute Fault zone in around itself that provide Gerdab spring water from this Fault zone. In order to behavior of Gerdab spring and discharge changes, can say this spring is kind of conduit-diffusion. This investigate create due to drabble spring water in winter that cause of low precipitation in the water year do not drabble spring water, but as regards fractures plan reason of spring muddy pothole sinkhole can be in anticline west limb. Statistical assessment and variation values of EC, bicarbonate, chloride and calcium shown that Gerdab spring is most probably connected to some other springs via reservoir source but attendant main drainage basin domain do not correlate. The dominant flow system seasonal Chapkooh spring located in west limb is conduit and it has a high discharge. The other springs such as Babaseyed, Chenare, Dorahan, and Barikab (located in east limb) in order to drawn diagrams and investigated it has diffusion dominant flow system

The Gulgir area covers 170 km 2 and is situated between ( 49° 25΄ 20″ to 49° 43΄ 20″ E and 31° 36΄ 17″ to 31° 48΄ 38″ N) in the northeast of Ahvaz and southeast of MIS at middle Karun watershed. Though, the Asmari limestone anticline is the main feeder of the Gulgir plain, but Hydrogeology and hydrogeochemically, Asmari and gypsum Gachsaran formations are respectively known for recharge and deterioration of Gulgir plain groundwater. In general, karst development of the Asmari anticline is immaure but karstification is more in the southwest limb as compare to the northeast one. In order to study hydrochemistry of the water resources, 17 samples were collected and analysed. Statistical analysis indicated that a good correlation existed between TDS and ions, except bicarbonate and this ion has neither correlation or it is reverse. The most correlation is observed between Na and Cl (99%). The groundwater quality is mainly subjected to gypsum, anhydrite, halite, dolomite and calcite dissolution and it is well depicted by composite diagrams. Four groundwater facies consisting of Cl-SO4, Ca-Mg, Cl-SO4-HCO3 and Ca-Mg-Na were observed. Generally, hydrochemical evolution has not occurred in flow direction. Groundwater in most part of the area are useable for drinking and water sample fall in C2S1 class for irrigation

 The study area is located in the north-east of Khuzestan province, southwest of Iran in Zagros structural belt and is dominantly covered by Fars group formation, in particular Gachsaran formation.The study area is placed in the geographic coordinates 50° 28' 30" to 50° 10' 30" 'east longitude and 30° 40' 40" and 30° 58' 30" north latitude. The aim of this investigation was to assess effect of different parameters on karstification, to make zonation of the evaporate karstic rock and to find out groundwater potential for various purposes in the area around Marun dam. In order to prepare, karstic development zonation map, lithologic, vegetation cover, fracture density, distance from the fracture, precipitation, slope, elevation layers and hierarchical analysis and fuzzy logic method was used. Based on Identification and extraction of effective parameters on karst development and integration of layer by hierarchical analysis and fuzzy logic method, the karstic study area was divided into 4 zones including karstified, transitional, low developed and undeveloped. To verify this classification doline density index was taken into account. The collected data indicated that well developed karst is observed in areas with low slope, low distance from fracture, approprite fracture density, favourable rainfall and well vegetation cover. Both the lime stone and gypsum evaporate rocks were subjected to karstification and though, lime stone bears fresh water but potential is low, while irrigation useable stored water in gypsum rock is considerable.

Abstract:
The Chenaneh plain with an area of 609 km2 is located in the west of Shush City and it is one of the promising aquifer in the northwest of Khuzestan province and the aim of this study is to determine hydrogeological behavior of the aquifer.
Due to complexity of the governing processes of groundwater, conventional methods of study and quantitative analysis of groundwater resources is a difficult task and further more it is time consuming. Thus, in order to better understand this valuable resources, numerical methods, for the sake of high performance, lower cost and fast response, mostly are used. In this investigation, assessment of hydro geologic characteristics of the Chenaneh plain has been carried out by simulation method using numerical finite difference model with the aid of MODFLOW 7.1. software. The appropriate software package was selected and conceptual model was developed. To design the model, the study area was divided into regular mesh and initial and boundary conditions and other necessary inputs were specified and were applied to the model. The designed model was calibrated in steady state condition for one month period in year 2010 and then was calibrated in unsteady condition from October 2011 to September 2012 in 12 stress periods and hydro geological parameters of the aquifer were optimized with aid of Pest package. The calibrated model was verified from October 2012 to May 2013. After calibration and verification and ensuring that the model could simulate aquifer conditions truly, the model was used as a management tool and some management scenarios including; predicting of aquifer condition in next 4years (2012- 2016), prediction of aquifer response to 10% increase groundwater withdrawal, groundwater situation with 50%, 25%, and 10% use of irrigation network water and water bearing horizon reaction to change in irrigation method were taken into account.
 

 The Zeydoun alluvial plain like an asymmetric syncline thrust is located between the Pazanan thrust (north) and Ragsefid anticline (south), between longitude 49° 42΄ to 50° 15΄ and latitude 30° 16΄ to 30° 41΄, in the south west of Behbehan City at about 180 km from Ahvaz in Khuzestan province. The surrounding geological formations of the study area include Gachsaran, Mishan, Aghajari and Bakhtiari conglomerate. The most important surface water body which partly feeds the plain is Zohre River. The area experiences semi-arid climatic condition with high temperature and low rainfall. The hydrochemical studies of the Zeydoun groundwater resources is based on analysis of 26 water samples collected on March 2012 and September 2013 and spatial and temporal qualitative changes were assessed. The result of hydrochemical investigation has shown that dominant anion and cation are chloride and sodium respectively. The samples were plotted on the Piper and Stiff diagrams and three hydrochemical facies such as Na- Cl, Ca- SO4 and Na- SO4 were observed. The hydrochemical iso-line parameters show an increasing trend towards the centre but ion concentration are decreasing at the end of the plain. Saturation index of water samples indicate that all samples are super saturated with respect to calcite and dolomite mineral and gypsum and halite minerals are under saturation. Based on Schouler diagram, groundwater quality for drinking in the southeastern part of the plains is average and in the central and the north west is inappropriate. Wilcox diagram indicated that groundwater quality of the Zeydoun plain placed in saline and very saline categories and are unsuitable for agriculture. The results of Statistical analysis showed that all the chemical parameters of the water samples were normally distributed and there is no significant difference between the average parameters in two seasons. A good correlation exist between chloride and sodium indicating halite dissolution of in aquifer. There is a good correlation between calcium and sulphate indicating Gachsaran dissolution as their common origin. There are two distinct categories in cluster diagram, and most of the samples are placed in the first category which showing Na- Cl facies.

 The Behbehan plain covers 464 km2 and located between latitudes 30º ״50 ׳29 to 30º ״18 ׳51 and Latitudes 50 º4 ׳25״ to 50 º24 ׳11״ in the southwest of Khuzestan province. The main geomorpholical feature of the plain known as Marun River trending west to east divides the area into north and south zones. Geological formations surrounding the Behbehan plain include lime stone, Gypsum, sandstone and conglomerate. Behbehan alluvial plain is mainly formed from weathering of evaporate and conglomerate rocks The main purpose of this investigation is to determine hydrochemical characteristics of groundwater, though hydrogeology of the area has been briefly pointed out. In general groundwater flow from the South-East South , North-East North, East of plain directed toward Marun River and output streams of the plain. The unit hydrograph fluctuate with rainfall and it is an influential factor to control water table changes. For chemical evaluation of groundwater 14 representative well samples of wet and dry season relevant to 1391-1392 were used. The chemical analysis of samples indicated that water quality in the northwest is suitable but in other parts, in particular, in the north and northeast due to gypsum formation water quality deteriorated. The increase in salinity around Behbehan City is concerned to anthropogenic activities (industrial and ….). The average total dissolved solids in wet and dry season are 2034 and 1984 mg/l respectively. The main groundwater facies is sulphate-calcium and both the ions disclose good correlation with total dissolved solids trend indicating significance of gypsum formation dissolution and in addition it reveals that groundwater salinity is mostly related to sulphate and calcium ions. There is a good association between sodium and chloride ions depicting halite dissolution. Based on Scholer diagram water quality varies from good to unacceptable for drinking purpose. With regard to Wilcox diagram water quality fall to C2S1 to C4S2 class and it is also crusting in nature.

 The study area is located at 35 km in the north east of Ramhormoz City and bounded between 49° 50 to 49° 40 E and 31° 30 to 31° 25 N. The catchment area of the Jareh dam reservoir covers 829 km2 and the Gachsaran formation occupies about 170 km2 of the Jareh dam watershed. In this study an attemt has been made to assess the effect of Gachsaran formation on water quality of the reservoir. For this purpose, water samples were collected from the reservoir and watershed in July 2013 and in addition to major ions (HCO3, SO4, Cl, Ca, Mg, Na and K), trace elements such as CO, Cd, Cu, Zn, Fe, Pb, F and Hg were analysed. Based on the depth measured electrical conductivity(EC), salinity were increasing with depth. The EC varied between 774 to 1277 /cm on surfacial parts of the reservoir and indicated increasing pattern from the lower to higher reaches. Potasium and sulfate ions indicated lower (0/15 mg/l) and higher(576/4 mg/l) concentration respectively. The input water depicted bicarbonate-magnesium facies while reservoir water facies is sulfate-calcium due to Gachsaran formation dissolution. Based on the saturation index, the Jareh dam reservoir water is unsaturated with respect to gypsum mineral. The Scholer diagram reveals that water is unsuitable for drinking and water falls in C3S1 depicting its use must be with pecular facilities.

 The Evan plain lies (between 46° 57´ to 49° 10´ E and 31° 48´ to 34° 58´ N), about 30 Km in the northwest of Shush City. In the east and the northeast of the area are located Karkheh River and Karkheh dam respectively. Though the main aim of this study is to evaluate qualitative characteristics of the Evan groundwater in 1386 and 1391, but in brief, quantitative behavior of the aquifer has been described. The hydro geologic characteristics include; hydraulic relation of the aquifer with surrounding water bodies, hydro stratigraphy assessment and their inter-relation, recharge and discharge zones. The hydro chemical characteristics incorporate, qualitative peculiarities in different parts of the area and governing impacts. The collected data indicated that groundwater flow path is from the north and the northwest towards the southeast and unit hydrograph is effected by Karkheh dam recharge and irrigation network. Based on 16 water samples (Mordad, 1386 and Esfand 1391), it was released that water quality in the northern parts is suitable, water quality degraded in the central and south due to distance from recharge zones. The first sequence (bicarbonate) of hydro chemical evolution is not observed in 1391 as compare to 1386, and water is saturated with respect to calcite and dolomite and gypsum saturation index is increasing in flow direction. In both the sampling periods, cluster pattern is dominantly observed in the north and middle parts of area reflecting closeness to recharge zone. Factor analysis indicated that in 1386 and 1391 two and three parameter are impacting groundwater quality respectively. In both the periods, the first and second factors are gypsum and bicarbonate dissolution respectively. Comparison of both the periods indicated that in 1391 pH has a bit increase and resulted in to be positive the third factor.

The study area is a part of Zagros structural belt in Khuzestan province and bounded between 49° 40´ to 49° 50´ E and 31° 25´ to 31° 30´ N. The study area is located about 35 km in the northeast of Ramhormoz City and covers territory of the Jareh reservoir dam. To understand relationship between geologic structures and the Gachsaran formation geomorphologic features, geologic structures were taken into account. The collected data indicated that the Jareh reverse fault, the Shir plain and the Anar plain thrust have seriously affected the study area and resulted in to enhance fracture density and in turn karstification development. Over 900 dolines were identified and a close relationship between doline development and faults was observed. Sink holes have been produced in fracture zones and lying in a linear trend. There is evident of a strike slip fault crossing the dam reservoir and in turn effected karst development and morphologic features. The investigation denoted two karstic horizons in the area, where the upper horizon occurs in the surfacial part of the Gachsaran formation and the lower one develop along the reservoir banks below water. Dominant parameters effecting karstification process include rain, lineament density, distance from lineament, slope, drainage density, lithology, vegetation cover and temperature. Using weight of these layers karstification potential of the area was determined. The potential map of the karstification was prepared with putting together effective layers in GIS10 media. Based on this map the upper karstic zone classified into four classes with high, medium, low and very low karstification. The marginal part of the area locating close to faults designated most karstification and a part of the area falls between the Shir plain and Anar plain implies lowest karstic process due to high erosion, presence of interlayer and alluvial deposits. In the lower horizon karstic phenomena expand along the dam reservoir bank and specifically in upper reaches.

The Silakhor plain which falls in Dez watershed occupies 819 km2 and is located at 269038 to 332538 E and 3702396 to 3698798 N in the northeast of Lorestan province. The young Dourod thrust fault is one of the important thrust of Zagros mountain belt in the southwest of Iran where revealed activities in recent decades. The morphologic evidences including drainage displacement, associated with strike slip fault depicts tectonic activities. As the 1384 and 1385 earthquakes in Borojerd and Dourod area was considered to be due to the young Dourod thrust fault activities, in this investigations effect of Dourod thrust fault on quantity of groundwater flow including; general flow path, hydraulic barrier, hydraulic connectivity, recharge, water escape and spring emergence and quality of groundwater have been taken into account. As the Dourod fault is an active thrust and it is believed to be responsible for 1384 and 1385 earthquakes in the area, in this assessment relation between water level fluctuation, springs and underground galleries discharge, spring emergence, general flow path and hydrochemical changes and earthquakes focus distribution have been taken into consideration. The results indicated that a good correlation exist between piezometers water level changes, EC and concentration of ions in pre and post earthquake is noticed.

 

The Qom plain covers about 456 km2 and is located between 3434 and 3419 latitude 5108 and 5049 longitude western part of the Salt lake in Qom province. The aim of this study was to evaluate groundwater quality with emphasis on major elements distribution. For this purpose 20 groundwater samples from deep wells in pre and post rainfall in 1390 was collected and were analyzed for major elements. In addition to major elements, T°C, EC, TDS and TH were measured. Based on the collected data, physico-chemical characteristics; distribution maps, hydrochemical diagrams; including: Stiff, Piper, Scholler and composite were prepared and the outputs data were used to assess governing hydrochemical processes, salinity sources, inverse modeling and usage of water for different purposes. The total dissolved solids of the Qom aquifer vary from 720 to 11000 mg/l and concentration of major ions due to halite and gypsum dissolution is increasing in groundwater flow trend from the north and the northwest towards center and the east. Water type is sulfate-sodium and chloride-sodium. Ion exchange process results in sodium dissolution and absorption of magnesium and calcium. The inverse modeling indicated that dominant phases mole transportation includes gypsum and halite dissolution. Based on Scholler diagram groundwater for drinking ranges from unsuitable to unacceptable and groundwater quality for irrigation dominantly falls in C4S4 class.

 

  The Dehgolan aquifer is the largest plain in Kordestan province. The plain is located at longitude 47° 08΄ to 48° 12΄ and latitude 35° 00΄ to 36° 00΄ and between Ghorveh township and Sanandaj City. The Dehgolan plain occupies an area of over 600 square kilometers. The alluvium of the plain has been formed as a result of surrounding rocks erosion in an embayment closed basin. The purpose of this study was to assess effect of Sangsyah reservoir construction on hydrogeology and hydrogeochemistry of the Dehgolan aquifer, such as aquifer shape, hydraulic connections to nearby water resources, hydrostratigraphic units, recharge and discharge zones, hydrodynamic coefficients, groundwater characteristics at various places and effective factors impacting on groundwater quality and to specify quantity and quality constraints of the Dehgolan aquifer. The information and data requirements such as; weather data, maps, satellite images, and piezometeric logs were collected and useable data were selected. Field studies including geology, identification of water resources, water sampling and etc were carried out. Geology of the Dehgolan plain was assessed from the point of view of stratigraphy, petrology, structural geology, geomorphology and impact of geological formations on water quality. The collected information demonstrated that granite, granodiorite erosion and fluvial sediments were formed the framework of the aquifer in the area. Sangsyah reservoir impounding began in March 2007 and consequently Sangsyah river flow diminished. Reduction of river flow seemed to be the most important factor to drop pizometers water levels in downstream of the dam. Hydrogeological studies showed that unit hydrograph of unconfined aquifer is influenced by seasonal rainfall and exploitation. The main water inputs into the aquifer are infiltration of rainfall, recharge from the Ghamlu River and underground flows from the South and south west directions. Evaluation of spatial and temporal qualitative changes of groundwater has been based on analysis results of 22 collected water samples in May and October 2013(after dam construction) and collected water sample in 2006 (before dam constraction). According to TDS map, the value of this parameter is high in the lower and upper part of the plain as compare to middle part. The reduction in TDS values results in from aquifer recharge from rivers and streams in the centre of the plain. Hydrochemical studies show that the Dehgolan groundwater type (before and after dam construction) is calcium -bicarbonate. Due to agricultural activities and overuse of fertilizers, the dominant contamination factor treating drinking water quality is nitrate.