Civil Engineering / İnşaat Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/13
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Conference Object Evidence for Sea Water Intrusion in Karstic Aquifer of Karaburun Peninsula, Nw Turkey(International Water Association, 2017) Baba, Alper; Gündüz, Orhan; Şimşek, Celalettin; Elçi, Alper; Murathan, Alim; Sözbilir, HasanKarstic aquifers are considered to be significant sources of groundwater and are mostly under threat due to sea water intrusion in many parts of the world. Seawater intrusion is also a common problem on karstic aquifers of Karaburun Peninsula in north of Mediterranean Region. The hydrogeology of Karaburun Peninsula is fairly complex and is mostly characterized by highly permeable karstic formations with significant water storage in an otherwise water scarce area. The karstic aquifers of the region were recently found to be under severe salt water intrusion, which significantly altered the position of fresh water/sea water interface as a result of excessive pumping and fault zones controlling the karstic network.Conference Object Investigation of Groundwater Recharges Mechanism in Alasehir Plain: From Physical Characterization To Modelling(International Water Association, 2017) Şimşek, Celalettin; Baba, Alper; Aksoy, Niyazi; Demirkıran, Zülfü; Hasözbek, Altuğ; Tayfur, Gökmen; Kumanlıoğlu, Ahmet; Durukan, Seda; Demirkesen, Ali Can; Murathan, Alim; Çağıran, Ömer; Akdeğirmen, Özgün; Tonkul, SerhatCharacteristics of aquifer that allows the flow of groundwater, recharge and discharge mechanism effect the available groundwater potential. In order to determine the available potential of groundwater, the budget components are the most important parameters. In general, different analogical methods are applied in different countries, instead of using measurable data. Determination of the groundwater recharge is the most difficult parameter to be measured among the hydrological budget parameters. In general, the analogical methods are insufficient to determine the groundwater recharge rate. Precipitation, evaporation-transportation and runoff can be measured from the surface meteorological station. However, estimation of groundwater recharge cannot be measured directly. At the moment of climate change, visualization of the spatial distribution of the groundwater recharge estimation and mapping are needed. Therefore, improvements of easy groundwater recharge techniques are very important tools for groundwater basins to develop the water management planning.Conference Object Investigation of sea water intrusion in the Ildırı Region (Çeşme-Turkey) coastal aquifer(Nevşehir Hacı Bektaş Veli Üniversitesi, 2017) Baba, Alper; Gündüz, Orhan; Şimşek, Celalettin; Elçi, Alper; Murathan, Alim; Sözbilir, HasanCoastal aquifers are considered to be significant sources of groundwater and are mostly under threat due to sea water intrusion as a result of anthropogenic (i.e., over exploitation, reduced recharge due to climate change, etc.) and natural sources (i.e., tectonic features and fault line orientations) in many parts of the world. Seawater intrusion is also a common problem on coastal aquifers of Turkey.Conference Object Investigation of Sea Water Intrusion in Coastal Aquifers: a Case Study From Karaburun Peninsula, Turkey(The International Association for Hydro-Environment Engineering and Research (IAHR), 2015) Baba, Alper; Şimşek, Celalettin; Gündüz, Orhan; Elçi, Alper; Murathan, Alim; Sözbilir, HasanGroundwater is an important natural resource; as of today, more than 2 billion people depend on groundwater. Determination of the quantity of available water resources is crucial due to continuously increasing water demand and unequal spatial distribution of water in the world. Coastal areas are typically considered to be areas of limited supply and large demand and groundwater is mostly the resource that is used for water supply purposes for coastal communities. Thus, there exist numerous studies in literature that focus on the determination of the groundwater characteristics in coastal regions with particular emphasis on the geological, hydrogeological and hydrochemical properties of coastal groundwater. Coastal aquifers are considered to be significant water resources and are mostly under threat due to salt water intrusion. The reason for salt water intrusion is mostly anthropogenic such as over exploitation but occasionally natural causes like tectonic boundaries or fault lines could be influential. When coupled with low recharge rates that are common in semi-arid regions such as the Mediterranean, effective and sustainable supply of water with sufficient quality and quantity becomes a real challenge for coastal communities.Conference Object Simulation of Groundwater Flow in the Gediz River Basin(European Water Resources Association, 2015) Elçi, Alper; Şimşek, Celalettin; Gündüz, Orhan; Baba, Alper; Acınan, Sezen; Yıldızer, Nilgün; Murathan, AlimThe objective of this paper is to present the approach and results of a groundwater flow modeling study that was conducted for the Gediz River Basin (GRB), located in western Turkey. The GRB is one of the most important, largest and stressed river basins in Turkey. This basin is agriculture-dominant; however significant competition for water exists among various stakeholders and sectors. The model is set up as a two-dimensional, finite-difference MODFLOW-2005 model that is solved for steady-state conditions, representing average annual groundwater flow in the basin. The main purpose of the groundwater flow model is to determine groundwater flow dynamics and water budget for the alluvial aquifers of the GRB. Pumping wells in the GRB predominantly withdraw water from these aquifers. A model-based estimate of the hydraulic conductivity distribution is also obtained. A two-stage modeling approach is taken to determine boundary conditions of the alluvial aquifer model domain. This approach results in two independently calibrated models that are referred as baseline and alluvial flow models. Modeled groundwater heads of both models provide an acceptable fit to observed data. The range of hydraulic conductivity (K) values is from 0.01 to 4451 m/d indicating a very heterogeneous aquifer. The median K value is 34.92 m/d and the standard deviation is 366.45 m/d. According to the baseline flow model budget, it can be concluded that the most significant groundwater input for the entire GRB is leakage from surface water such as dam reservoirs and the Gediz riverbed. In the alluvial aquifer, surface water still plays an important role in the water balance, however lateral flows across aquifer boundaries are the most important component. Also, groundwater extraction is larger than groundwater recharge by precipitation.Article Citation - WoS: 20Citation - Scopus: 22Modeling of Seawater Intrusion in a Coastal Aquifer of Karaburun Peninsula, Western Turkey(Springer Verlag, 2017) Mansour, Ahmed Y. S.; Baba, Alper; Gündüz, Orhan; Şimşek, Celalettin; Elçi, Alper; Murathan, Alim; Sözbilir, HasanSeawater intrusion is a major problem to freshwater resources especially in coastal areas where fresh groundwater is surrounded and could be easily influenced by seawater. This study presents the development of a conceptual and numerical model for the coastal aquifer of Karareis region (Karaburun Peninsula) in the western part of Turkey. The study also presents the interpretation and the analysis of the time series data of groundwater levels recorded by data loggers. The SEAWAT model is used in this study to solve the density-dependent flow field and seawater intrusion in the coastal aquifer that is under excessive pumping particularly during summer months. The model was calibrated using the average values of a 1-year dataset and further verified by the average values of another year. Five potential scenarios were analyzed to understand the effects of pumping and climate change on groundwater levels and the extent of seawater intrusion in the next 10 years. The result of the analysis demonstrated high levels of electrical conductivity and chloride along the coastal part of the study area. As a result of the numerical model, seawater intrusion is simulated to move about 420 m toward the land in the next 10 years under “increased pumping” scenario, while a slight change in water level and TDS concentrations was observed in “climate change” scenario. Results also revealed that a reduction in the pumping rate from Karareis wells will be necessary to protect fresh groundwater from contamination by seawater.Article Citation - WoS: 14Citation - Scopus: 17Blowout Mechanism of Alasehir (turkey) Geothermal Field and Its Effects on Groundwater Chemistry(Springer Verlag, 2017) Rabet, Rita Sandrina; Şimşek, Celalettin; Baba, Alper; Murathan, AlimAnatolia region is one of the most seismically active regions in the world and has a considerably high level of geothermal energy potential. Some of these geothermal resources have been used for power generation and direct heating. Most of the high enthalpy geothermal systems are located in western part of Turkey. Alasehir is the most important geothermal site in western part of Turkey. Many geothermal wells have been drilled in Alasehir Plain to produce the geothermal fluid from the deep reservoir in the last 10 years. A blowout accident happened during a geothermal well drilling operation in Alasehir Plain, and significant amount of geothermal fluid surfaced out along the fault zone in three locations. When drilling string entered the reservoir rock about 1000 m, blowout occurred. As the well head preventer system was closed because of the blowout, high-pressure fluid surfaced out along the fault zone cutting the Neogene formation. In order to understand the geothermal fluid effects on groundwater chemistry, physical and chemical compositions of local cold groundwater were monitored from May 2012 to September 2014 in the study area. The geothermal fluid was found to be of Na–HCO3 water type, and especially, arsenic and boron concentrations reached levels as high as 3 and 127 mg/L, respectively. The concentrations of arsenic and boron in the geothermal fluid and groundwater exceeded the maximum allowable limits given in the national and international standards for drinking water quality. According to temporally monitored results, geothermal fluid has extremely high mineral content which influenced the quality of groundwater resources of the area where water resource is commonly used for agricultural irrigation.Conference Object Citation - Scopus: 4High Arsenic Levels in Groundwater Resources of Gediz Graben, Western Turkey(CRC Press, 2016) Baba, Alper; Gündüz, Orhan; Şimşek, Celalettin; Elçi, Alper; Sözbilir, Hasan; Murathan, AlimGediz Graben situated in western Turkey is an area containing extensional structures with active tectonics and geothermal systems that serves as a suitable environment for the presence of high levels of arsenic (As) in groundwater. The results of a comprehensive monitoring program in the basin revealed that the maximum As concentration detected during the monitoring program was 3086 ppb and the average value was calculated to be 23.63 ppb. In addition, As levels in 28% of the water samples were above the 10 ppb limit value making them unsuitable for drinking water supply. These high As concentrations in the basin was mostly associated with long detention times of water in altered rocks located along detachment faults, strong water–rock interaction processes in the alteration zones and anthropogenic influences made within the geothermal fluid reservoir. © 2016 Taylor & Francis Group, London.