Journal of Engineering Geology

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(paper pages 227-240) The Famenin,Kaboudar-Ahang,Ghahavand plains are located in the north of Hamedan province.The sediment thickness of thier aquifers is about 70-100 meters .In recent years, some big and dangerous sinkholes have been developed in this area.By the result of excavations that done in these plains and investigation of the sourrounded outcropped area,it was found that the bed rock of this area has been made of Oligo-miocen limestones. According to the field observation,the measuring of joints and fractures systems, stud of thin sections, characteristics of excavations, yield of wells, the results obtained by chemical experiments of water and the estimation of parameters such as saturation and stability indexes,the amount of free carbon dioxide and the primary pressure of carbon dioxide gas,it was concluded that the Karstification phenomenon was happened in the bed rock and the Endokarst structures exist in it. Thus,The exist of Endokarst in bed rock cased to wells have been had high yield and Sinkhole were made in these area.In order to avoid or reducing the occurrence rate of Sinkholes in this area, we should avoid digging new wells in the bed rock and should stop the pumping of wells which have been drilled in the bed rock and have high yield.

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In this study, seepage phenomena through the left abutment of Marun dam are investigated. The Marun dam is a 170 m high rock fill dam, which regulates the waters of the Marun River, serves power generation, and flood control and provides irrigation needs. The dam site lies in the Zagros Mountains of southwest Iran. This region presents continuous series of mainly karstic limestone, marl, shale and gypsum ranging in age from Cretaceous to Pliocene. The region has subsequently been folded and faulted. All underground excavations are sited in the left abutment. The spacing of the diversion tunnels and pressure tunnel is considered to be acceptable, meaning relatively short, thus requiring 2 row grouting curtain into both embankments. Prior the reservoir impoundment, the concrete plug was constructed into the middle section of second diversion tunnel. Upstream section of tunnel was not concreted. During the first reservoir impounding, the old karst channels along ‘Vuggy Zone’ cut by the second diversion tunnel were reactivated and leakage occurred. The total amount of water leakage through the left bank of Marun dam was about. The unlined second diversion tunnel had a key role in connecting reservoir with karst conduit system. On the basis of detailed engineering geological analysis, the concept of remedial works was carried out. The main points of this concept are one of row grout curtain extension up to the section with shaly interbeds declared as watertight Asmari sequence (close to the watertight Pabdeh formation) and plugging of accessible section of main karst channel by concrete. In order to determine the seepage direction and karstification pattern, solubility studies were done. Also pinhole, XRD and XRF tests were carried out. The major joint system and interbedding cracks have predominant role in karst evolution process. Hydrogeological role of joints, perpendicu-lar to geological structure, is not negligible. As a result of these studies, seepage paths have been identified in the karstic limestone in the left abutment of the dam.

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The previous studies underteaken in the region indicate that the Ekhtiarabad and Chah-Darya sinkholes have occurred as a result of dissolution of underground gypsum rocks. Hence, they represent the likelyhood of hidden and threatening caves in the region. The presence of gypsiferous formations having surficial karstic features attest to this supposition. So, in order to determine the possible dissolving sites which may contain caves, the electrical conductivity and evaporite dissolution index maps of Kerman-Baghin aquifier were prepared and matched with groundwater recharge and mobility conditions. Accordingly, four suspected hidden- cave sites were recognized which include a large area around Ekhtiarabad village (as the most suspected site), one spot at the northwest of Baghin Plain and two other areas (south of Baghin and south and southwest or Kabutarkhan). Based on the utilized hydrogeochemical criteria, these last two areas may contain hidden caves, but, due to unsuitable hydrodynamic conditions, the possibility seems weak.

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This research focuses on the identification and description of various features of pseudokarst in different parts of Alvand granitic batholith, Hamedan, west of Iran. In the literature, karst features have been presented as specific types of terrain or landscapes with particular characteristics suites of well-known surface and subsurface dissolutional forms. Whereas, pseudokarst refers to non-dissolutional surface or subsurface features and landforms created in different areas such as slopes, coastal lines crushed stone areas, lava tubes and permafrost regions. In this research, a comprehensive field investigation program has been carried out. During the field investigations, the most important features of pseudokarst in Alvand granitic batholith have been recognized and classified. Results show a wide range of pseudokarst features in the Alvand granitic rock masses. These landforms are created by erosion, weathering processes and some holes caused by rock block movements along the rock slopes. Some of the most important forms and features of the pseudokarst in the studied area are consist of tafoni, genama, pseudokarren, talus caves, caves associated with the residual blocks and erosional forms along joints and fractures within the granitic rock masses

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In this research, the relationship and reaction between quantitative and qualitative Shahre Rye spring’s karstic water (Cheshme Ali) and spring’s adjacent alluvium aquifer have been considered to determine the relationship between alluvial and karstic aquifers and to study the connections between the two different groundwater environments. The results of the present research suggest geological conditions, hydrogeology and different hydraulic condition between Cheshme Ali karstic water with its surrounding alluvium’s aquifer. However the study results show the lack of a hydraulic connection between the two different groundwater environments (karst and alluvium) that are formed by north Rye fault.
Introduction
There have been many studies in the field of the present research, some of which are mentioned below.
(Tobarov, 1966). The N. Massei et al. (2002). (Robert E. 2005). (Ezatollah Raeisi 2008). (Cholami et al. 2008). (N. Goldscheider and C. Neukum 2010). (Dusan Polomcic et al. 2013).
The aim of this research is to identify the hydraulic relation between the alluvial aquifer and the karstic aquifer of the Cheshme Ali, during which the geographic, topographic and geologic situations and the changes in water discharge of Cheshme Ali and the changes in water table of the observation wells of the aquifer to the north of the spring have been reviewed simultaneously.
The results indicate a lack of relation between the alluvial aquifer and the karstic aquifer of the Cheshme Ali in Shahre Rye.
The general specification of the study area
The surface area of Shahre Rye equals to 2,293 km² and the city is limited to the north by Tehran, to the south by Qom, to the east by Varamin and Pakdasht and to the west by Islamshahr, Robat Karim and Zarandieh (Fig. 1). The Cheshme Ali is located in the eastern parts of the city and southeast of Tehran. From a geographic point of view, the Cheshme Ali spring is situated in the southern part of the Cheshme Ali hill, and after leaving the ground, the spring's water flows to the south of Shahre Rye.
Methodology
1. Topography
The topographic specifications of the Cheshme Ali and its surrounding are as follows:
The highest points of the Cheshme Ali's surroundings are the Sepaye Hills with an altitude of 2,085 m above the sea, which are located to the east of Cheshme Ali. The height of Bibi Shahbanoo hill to the southeast of Cheshme Ali is about 1,498 m. The altitude of the northern hill of Cheshme Ali, where the spring is located is about 1,077 m and the lower sloped land surrounding it have an altitude of 1,072 m above the sea. This means that the opening of the Cheshme Ali spring is located at 1,072 m above the sea.
2. Geology
From the geological point of view, the existing units around Cheshme Ali of Shahre Rye consist of Precambrian, Mesozoic and Cenozoic sediments and rocks as geological specifications of Cheshme Ali and its surroundings are shown in Fig. 2.
From the structural geology, and geological specifications two geological sections AB, CD Were prepared and presented in Figure 3.
The Figure 3 shows, Cheshme Ali spring appears from Cretaceous thick layered limestone (Tizkooh formation Kt1) and the shahre Rye fault mechanism on either side of layering. However the water flow of cheshme Ali is nearly east – westerly after spring’s openings (A) and then spring water flow direction is to the south (Fig. 4).
The hydrogeology of the spring and the wells
1. The Cheshme Ali in Shahre Rye is a karstic spring, with few hydrogeological specifications that are concluded from the result of geological and hydrogeological review and analysis of the spring’s water quality.                                                           
Therefore, the karstic Cheshme Ali spring has a varied range of discharge which is from medium (25 to 100%) to high (>100%). Moreover in the curves of the spring’s discharge and simultaneous rainfall, shown in figure 5, the peak volume of water discharge of the spring corresponds fully with the peak rainfall, underlining the influence of simultaneous rainfall on the spring.                
The study of the hydrographic makeup of the spring (curve 2) shows the difference in the period between the upward curve (seven and a half months) and the downward curve (four and a half months) underlining the lower permeability of the spring’s intake area versus the grounds conducting spring water to the openings.
2. The hydrogeology of the surrounding wells:
For the purpose of studying the fluctuation of water tables of the observation wells around the spring and in its adjacent alluvial aquifer, the isobaths maps of groundwater level and groundwater table of the spring’s surrounding areas were drawn ( Fig.6). The level of groundwater table to the north of spring is 5.9 m and 6.6 m to the south of it, while the spring water is at ground level. In order to have a better understanding of the potentials of groundwater table in Shahre Rye’s Cheshme Ali and its surrounding environments from south to north, the potential profile is provided in figure 7 using the potential figures of witness wells and the Cheshme Ali spring. In the potential profile, the groundwater level of the Cheshme Ali is higher than the groundwater potential level of the witness wells, which seems to suggest the recharge of the plain by the spring.
The review of the groundwater quality in wells and the Cheshme Ali spring
The groundwater quality characters of the Cheshme Ali and the wells to the north and south of the spring are presented in table 2,that shows three differences and similarities in the results of the chemical analysis of water from Cheshme Ali and from wells located to the north and the south of the spring. The difference between the chemical composition of water from the spring and the chemical composition of the well located to the north is considerably more than the difference between the chemical compositions of the spring and the well located to the south.
Summary and conclusion
Based on the geological studies of this research, the Cheshme Ali spring in Shahre Rye appears from the Karstic Tizkooh formation (Fig. 2) and the geological structure shows a northerly direction for the slopes of the layers in Tizkooh formation, and an east-westerly direction for the appearance of the spring water (Fig. 3 and Fig. 9). The spring’s flow is disseminated and the spring is of Karstic - fault type (table 1). The discharge of Cheshme Ali corresponds entirely to rainfall and is influenced a lot by it (Fig. 5). The condition of groundwater table of the well and the spring (Fig. 6, A) and the water level potential of the spring and its surrounding wells underlines the existence of two different hydraulic environments (Fig. 6, B). Moreover, from the aspect of potential groundwater column, there is a large difference between the groundwater table potential of the spring and the potentials of the two wells to the north and south of the spring (Fig. 7and8). From a qualitative aspect, the quality of spring water differs greatly from the quality of water from the wells located to the north and south (table 2).
The results of this research are as follows:
1. The study of geologic, structural geology and the geological section shows the water in the Cheshme Ali of Shahre Rye is originating from the Karstic formation of Tizkooh that layers sloping are to the north, the spring water appears from the site of the Rye fault and then flows to the west.
2. The studies have proven that Cheshme Ali to be a Karstic – fault spring with disseminated flow, whose discharge is influenced by rainfall and condition of groundwater level and the table which underlines the alluvial aquifer shows lack of relation between two alluvial and karstic aquifers.
3. The water quality analyses show a great difference between the specifications of the spring water and its surrounding wells groundwater.
4- The north Rye fault mechanism are formed two different groundwater environment ( Karstic and alluvium) and however different groundwater conditions between north and south of alluvium.

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