International Journal of Agriculture and Crop Sciences. Available online at www.ijagcs.com IJACS/2013/5-1/30-35 ISSN 2227-670X 2013 IJACS Journal Studying Hydrodynamic Geological Formations of Mahidasht Basin in the amount of Plain Feeding using RS & GIS Mansour Parvin 1, Mehdi Ahmadi 2, Fatemeh Manochehri 3 1. Department of Natural Geography Geomorphology,Payame Noor University,PO BOX 19395-3697 Tehran, IRAN 2. MS at Natural Geography, University of Tarbiat Moalem,IRAN 3. Graduate student, University of climate Tabarestan,IRAN Corresponding author email: mansorparvin@yahoo.com ABSTRACT: Mahidasht water table hydrology is separated from three north, east and south directions. By surrounding environment, we mean Kermanshah plains in north part, impermeable formations in south and hydrologic area in east. The plain is separated by the intervention of two geological formation factors of Kermanshah plain. Siliceous, lime and marnite formation northwestsoutheast extension is related to low Kertase and the limes have diversity in terms of color, texture, morphology and probably composition. This article is aimed at hydrodynamic study of geological formation of Mahidasht basin (scale 1:50000), and field studies, aerial and satellite images of the zone and topographic plots were used (scale 1:25000). Results show that the depth of ground water changes between %43m and 17.9m; minimum level in Abasabad is located in northwest plain and maximum in Lalabad and Amiran formations margin in south plain areas. Key words: hydrodynamic, geology, Mahidasht, RS INTRODUCTION Various formations have occupied the surface of the ground. In some points, the formations are covered by a layer of soil, yet on the others, uncovered formations can clearly be seen. If we have a close look into different formations, we will find out that all formations making the solid skin of the earth have empty spaces appearing in different dimensions and forms. Some of them (like the spaces existing in lime formations) are too small to be seen with unarmed eyes but in some Karst lime formations the spaces appear with the length and width of several meters. Ground water locates between these empty spaces. Surface waters of Kermanshah province are resulted from snow and rainfall from west winds blowing from Mediterranean and Atlantic Ocean toward Iran (power ministry, 1999) and as a result of snow melting and abundant precipitation, many rivers are running off the province to Persian Gulf basin. Among the main rivers of the province are Gharesu, Gamasiam, Ravand, Sirvan rivers (power ministry, 2009) as well as Marg River and also Tiran, Mirazizi, Khivar Burbur and Gharehdaneh streams and also waters originated from snow melt of the heights locating in south Kermanshah like Sabzamu, Nesar and Sefidkuh heights can be mentioned (Enayati, 1993). In fact, the river is considered as the drainage of Mahidasht water (Azizi, 1983). Mahidasht basin (with an approximate area of 839.59km) is located in west and southwest of Kermanshah (Kahrizi, 2010). The heights are composed of different geological formations such as Kertase lime, Gurpi formations, Fars series surrounding the plain (west regional water organization, 1999). The alluvium is composed of debris silt, sand and clay layers with an estimated thickness of 80m (Kahrizi, 2010). The material of the floor rock varies regarding different geological formations but the obvious is that Kertase limes seem to cover the main part of the plain (water and soil consulting engineers, 2000). The plain feeding resources are from atmospheric precipitations on the heights in particular surrounding lime heights and also Marg River passing throughout the plain (Tamab consulting engineers, 2003) and joining to Gharesu river in a place called Marg Doaab. Regarding the previous studies in the fueld, Shah et al (2002) believed that the indicators of ground water tables on the ground are shown by geological, geomorphic, vegetation cover and soil conditions units. Revindran (1992) also believed that it is possible to determine the ground water potential of a zone using local plots like geology, soil, and geomorphology. Kamareje (1996) developed a model for evaluating ground water potential using GIS
extracting lithology, geomorphology, structure and feeding conditions from remote sensing data and then each of the existing factors were weighted and in the end the ground water plots were gained. MATERIALS AND METHODS Here, basic geology plots and geomorphology plots with scale 1:50000 and topography plots with scale 1:25000 of Mahidasht were used to determine the role of geological formations in the basin feeding. Aerial and satellite IRS images and also panchromatic band image were used for local resolution out of which characteristics of soil, the amount of clay, lineaments and cover plot of the zone were extracted. To provide fracture and fault plots, topography plots were used. much of the existing information was gained via geological plots of Mahidasht and Robat zones. Information gained from the field studies was also added to these information including soil sampling which comprised sincules and zones with the capability of transferring water to the level below used in determining the permeation capability of the surface run offs. Also, slope and slope direction and vegetation cover and usage plots were used in the extent of permeability. Respective plots were prepared based on WGS1984 image system and based on UTM universal image system, and their systems were defined. Results from Geological Plots and Data Geological formations and their role in feeding Mahidasht plain Limes K1 Cause of a general slope toward Kermanshah, the limes probably have no role in feeding Mahidasht groundwater. Besides, they have also a compressed siliceous and marnite texture which consequently their porosity make the limes working weak in transporting the water (Parvin, 2011) (Figure 1). Gurpi Formation Cause of its ingredients, the formation comprises silicate, shale, and marnite. It is suitable for feeding groundwater and just its lime passage can play a weak role in feeding groundwater which has no outcrop in the plain (Figure 2). Figure 2. Gurpi formation Figure 1. KL formation Amiran Formation This formation also is not porous regarding the characteristics of its ingredients and does not interfere in Mahidasht aquifer (water and soil organization of Kermanshah province, 2009). So, Amiran formation has relatively isolated this in southern parts. True feeding near the formation is to surface flows running through the waterways and floods at the time of atmospheric precipitations and resulted in the areas underground aquifer cause of the high amount of rocks in Amiran formation.
Aghajari Formation The formation has an outcrop in west Mahidasht which is not hydro-dynamically good and plays no role in feeding the plain groundwater (Figure 3). Figure 3.Aghajari formations However, the sections significant regarding groundwater exploitation are: Southeast Section of Mahidasht Plain composed of low hills and varying alluvial thickness (Amiri, 1991); the alluvium of the part with a combination of very fine grain sandstone has small thickness about a few meters to 90m (in newly drilled wells) in some parts (Parvin, 2000). Among the reasons can be mentioned for the thickness is the existence of Gurpi shale formations (west regional water organization, 1999) located at north and south margins of the area, the floor of which is probably composed of rocks based on the drilled wells log. The formation is probably weathered and eroded under intense tectonic evolutions with severe climate changes (organization of geology, 1999) and became locally deeper in some areas. And upon being filled by alluvial sediments, it has accommodated further thickness of the alluvium, however, further geophysical exploration is required to reassure from the happening of the phenomenon (Figure 4). Figure 4. exploitable Southeast Section (maximum feeding possibility) The Main Underground Aquifier of the Central Section of the Plain the table begins along a line connecting Zalan, Reshvehgar and Jushkan villages (Azizi, 1983) and then extended toward southwest plain with its depth increasing in the same direction. Maximum depth of the alluvial table must be located at north plain area between Seyyed Jacob Ghamshe and Gelineh (Khaki) Castle (Ministry of Power, 1999) based on the results from the discovered wells surrounded by Moshaver water and soil, and the resulting geological cross sections. Alluvium thickness is estimated about 200m and its floor rock is of lower Kertase lime probably covered by conglomerate founded in 200m depth. The depth of alluvium reduces
significantly toward south plain so that it becomes about 10m near south plain formations (Ministry of Power, 1999). These depth changes might show a fault occur in the line with northern lime formation resulting in a deep valley revered by alluvial sediments later. The underground aquifer of the section is of open tables and its alluvium contents are mainly clay with a mixture of sand and gravel which are not mush rough grain (Geological plot of Kermanshah, 2009). In parts of the aquifer like Namivand and Ghelichkhani, sand sediments layers are found composed of rock and gravel which seem to have the conditions of semi-surrounded tables. Along with the plain pivot and in the middle, where the alluvial sediments thickness is about 100m there is a aquifer composed of sand surrounded by a clay layer with a thickness about 20 to 30m and a small artesian eruption (about 2 l/m) is observed from one of the wells discovered on its surrounding (Figure 5). Figure 5. the main underground aquifer of the central section (un-exploitable) Results from Data Analysis and Discussion Groundwater in Mahidasht plain is under the conditions of open and surrounded aquifers. In the area of Pirhayati in the discovered well (1014-D) is faced with Azterin pressure (West regional water organization, 1999). In most area, there is a conversion of surrounded to semi-surrounded aquifer beside the free aquifers. It is inferred from the geology of the plain and lagoon level in the surrounded aquifers that in parts of it are regionally connected to the open sections. Groundwater levels are principally measured from low depth wells, but it is obvious from the curve design consistency that lagoon level consumption is regional. In some places, water level shows 1 to 2m difference that the idea enhances the threat to aquifers area. Generally, groundwater level varies between 43 to 17.9m in the plain; minimum level in Abasabad is located in northwest plain (Figure6) and maximum in Lalabad and Amiran formations margin in south plain areas (Figure7). Figure 7.maximum water level (La'labad) Figure 6. minimum water level (Abasabad)
It seems that groundwater direction in Mahidasht, south Marg River (except in a small part which is toward Marg) is in parallel with it (Agriculture Jihad Organization of Kermanshah province, 2009). Hydraulic flow slope is naturally low in places with narrow aquifer thickness, i.e., near impermeable borders and in south plain areas and also cause of low permeability as a result of approximation to Amiran formation (Mahdavi, 1992, p25). As said earlier, Mahidasht (an area of 839.59km) is located at southwest Kermanshah with a longitudinal northwest and southeast extension (Armed Forces Geography Organization, 1999). Floor rock type varies based on various geological formations, but the obvious is that Kertase limes covering the plain floor mainly are the feeding resources from the streams running off the heights in particular surrounded lime ones and also Marg River passing throughout the plain and joining Gharehsu in a place called Marg Doaab. Groundwaters direction here in the plain is from south and southeast of Mahidasht Robat to northwest and north. In the groundwater aquifer in the plain is founded in the aquifer stratum with thickness between 10 (southeast part) to about 20m (central part), alluvium depth change from 20m to a few 10m is possible cause of layers fracture in northern heights length which deepen the valley and us later filled by alluvium. The aquifer layer in the plain is open yet resulted in semi-surrounded aquifers along the pivot with remaining sand layers in some parts and in particular in Khani, and Namivand areas. They form the surrounded aquifer in some artesian areas. In Mahidasht plain, groundwater depth is between 1 to 9m (an average of 2.5m) in end fall and between 0.5 to 8m (an average of 1.5m) and maximum 2 to 4m in spring. Further depth is observed in east hills of Mahidasht and lower depth around Chaghanarges village, north Mahidasht and cause of the areas the groundwater is under pressure in most parts and even in some artesian areas. Transferability index is not the same everywhere cause of type and thickness change of aquifer layers; it is about 100m 2 on the heights margin in debris formations, 250m 2 a bit lower and finally over 500m 2 in the center of east plain in a day the maximum amount of which is on southeast areas of Kermanshah-Islamabad road where the thickness of aquifer layers increases and is determined about 1300m 2 a day (Figure 8). Figure 8. The depth of water stillness in Mahidasht basin regarding geological factor CONCLUSION Mahidasht zone is extended in northwest-southeast direction and limited by the heights of the same direction. Northern heights have upper Kertase limes which are very extended and significantly thick which are significant in reserving atmospheric precipitations and alluvium feeding of the plain regarding the tectonics of the zone. Extension of the springs with suitable aquifying ability on the edge of the formations approves the matter that the southern heights have better lithological diversity than the northern heights cause of the outcropped formation types which are mainly composed of Kashkan Basen Paleotsen to Eosen evaporation sediments and of silstone and sandstone and red Glonmerate with no significant effect on reserving atmospheric precipitation and aquifer feeding and can affect only the zone aquifer. Amiran formation margin is in south parts of the plain (minimum water stillness level is on Dec.-Jan. and maximum on April-May). Respective unit hydrograph is on April-May of that year. And finally, the water stillness level of the aquifer was
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