Civil Engineering / İnşaat Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/13
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Book Citation - Scopus: 6Climate Change and Its Effects on Water Resources: Issues of National and Global Security(Springer, 2011) Baba, Alper; Gündüz, Orhan; Friedel, Michael J.; Tayfur, Gökmen; Howard, Ken W.F.; Chambel, AntonioNational and global security can be assessed in many ways but one underlying factor for all humanity is to access to reliable sources of water for drinking, sanitation, food production and manufacturing industry. In many parts of the world, population growth and an escalating demand for water already threaten the sustainable management of available water supplies. Global warming, climate change and sea level rise are expected to intensify the resource sustainability issue in many water-stressed regions of the world by reducing the annual supply of renewable fresh water and promoting the intrusion of saline water into aquifers along sea coasts where 50% of the global population reside. Pro-active resource management decisions are required, but such efforts would be futile unless reliable predictions can be made to assess the impact of the changing global conditions that would impart upon the water cycle and the quality and availability of critical water reserves.Conference Object Citation - WoS: 1Effect of Water Source on Human Health: a Case Study From Biga Peninsula, Turkey(2009) Baba, Alper; Gündüz, OrhanThe concentrations of certain elements including arsenic (As), fluoride (F) and aluminum (AI) were measured in groundwater in the different part of Biga Peninsula which is located in the western parts of Turkey. The concentration values of As and AI in groundwater ranged between 10-40 ppb, 0.5-0.8 ppm and 1-11.5 ppm, respectively, in this region. Al values exceed the Turkish drinking water standard value of 0.2 ppm. Furthermore, As concentration in water from alteration zones exceed the drinking water standard value of 10 ppb. Based on this background, this study was intended to investigate the source of these heavy metals and its neurotoxin effects on human health as many people living in this region have undergone medical treatment, which are believed to be related to the quality of water resources originating from densely altered volcanic rocks.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 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 Citation - WoS: 2Citation - Scopus: 2Arsenic in Groundwater in Western Anatolia, Turkey: a Review(University of Silesia Press, 2010) Gündüz, Orhan; Baba, Alper; Elpit, HandanOccurrence of arsenic (As) in groundwater has been a major problem worldwide for the last hundred years. Considering its toxic effects on human health, the presence of elevated levels of arsenic in groundwater resources used in drinking water supply has been an active research field throughout the world (Van Halem et al., 2009). In this regard, case studies from Bangla-desh, India, Nepal, El Salvador, Ecuador, Honduras, Mexico, Chile, China, Canada, Argentina, Peru, Taiwan, United States, Bolivia and Turkey have been documented with regards to the detection of natural levels in groundwater, the occurrence and distribution mechanisms, the human health effects and the in-situ and ex-situ treatment techniques (Jean et al., 2010). In many of these locations, arsenic is naturally found in the subsurface strata within volcanic and sedimentary formations as well as in areas of geothermal systems related to tectonic activity. Western Anatolia in Turkey is one such area of complex geology with active tectonics and high geothermal potential. This natural setting serves as a suitable environment for the presence of high levels of arsenic in subsurface waters. Based on these fundamentals, this study presents a general overview of arsenic presence in western Anatolia.Conference Object Sustainability of Groundwater and Its Effects on Ecosystems(National Academy of Sciences of the Kyrgyz Republic (NAS KR), 2011) Baba, Alper; Gündüz, OrhanGroundwater’s global role as a vital source of fresh drinking water is well documented, and efforts are underway in many parts of the world to manage groundwater reserves responsibly and sustainably. A large percentage of the world’s population lives in cities and either depends on or is affected in some way by groundwater. This ever increasing demand on groundwater has led to overexploitation of the aquifers and degradation of groundwater quality particularly in the last 50 years. Available evidences indicate that regional changes in climate (i.e., increases in temperature and reduction in precipitation totals and patterns) have already affected groundwater resources and ecosystem in many parts of the world. In future, climate change is expected to intensify groundwater related problems due to reduced recharge rates and increased demand for domestic, agricultural and industrial water supply. Thus, the basic concern is the sustainable management of groundwater resources such that it is not depleted while the increasing demand is effectively satisfied. Based on these fundamentals, the purpose of this study is to present an overview of groundwater problem in different parts of the world and to present an overview of the current knowledge in the area of climate change impacts on water resources. Case studies from the Mediterranean Region, the Caspian Sea Region and the Aral Sea where safe water resources are typically scarce and became steadily scarcer are presented. In particular, access to high quality drinking water will become more of a problem than it currently is in these and in many other parts of the world. Decreasing precipitation and reduced recharge of groundwater resources are now considered to be one of the reasons for declining groundwater quality. Finally, these drastic changes in the hydrology of the groundwater system are also responsible for many changes in ecosystems where some are irreversible.Conference Object An Integrated Assessment of Water Quality in an Arsenic Containing Aquifer: Milestones From Hydrogeology To Public Health(American Society of Civil Engineers (ASCE), 2012) Gündüz, Orhan; Şimşek, Celalettin; Elçi, Alper; Baba, Alper; Bakar, Çoşkun; Gürleyük, Hakan; Çakır, A.; Mutlu, MerdiyeA multi-disciplinary research is being conducted in Simav Plain, Turkey where an arsenic containing aquifer is at the center of attention. The study is not only aimed to understand the sources and mechanisms of the presence of high arsenic levels in groundwater but also to determine the associated consequences with regards to human health. The high arsenic levels in most groundwater (N=33, avg. 162 ppb), surface water (N=9, avg. 76.6 ppb) and geothermal water (N=3, avg. 406 ppb) samples are strongly related to high occurrences of arsenic in rocks and soils of the plain, which range between 7.1 and 833.9 ppm with an average of 49 ppm. These values correspond to several orders of magnitude higher than international standards and world averages in water and soil, respectively. With this motivation, this research also focuses on human health in the study area associated with exposure to these high arsenic levels via numerous pathways. Consequently, more than 1000 individuals were personally surveyed by public health specialists to determine an inventory of diseases in the area. Furthermore, a verbal autopsy study was also conducted with relatives of the deceased, which were further verified with hospital records, to understand the underlying death cause. As a result, certain cancer rates were found to exceed national averages and the results statistically demonstrated a potential link with high arsenic levels mainly through oral exposure.Conference Object The Use of Cokriging Algorithm for Arsenic Mapping in Groundwater Systems(American Society of Civil Engineers (ASCE), 2012) Gündüz, Orhan; Elçi, Alper; Şimşek, Celalettin; Baba, AlperAccurate mapping of the spatial distribution of arsenic in groundwater is an important but equally difficult task to complete due to a number of uncertainties. Classical univariate interpolation algorithms could sometimes be insufficient to capture high concentration and high gradient areas. Under these circumstances, the use of an auxiliary parameter could provide better estimates of arsenic distribution. Based on this premise, arsenic cokriging with a correlated parameter can improve the performance of interpolation and can enhance the quality of predictions. In order to test this hypothesis, a water quality dataset from an arsenic containing aquifer in Simav Plain, Turkey is used to develop arsenic distribution maps. Arsenic is cokriged with correlated parameters such as manganese, iron and dissolved oxygen; and the results are compared with univariate interpolation algorithms such as ordinary kriging and inverse distance weighing. The comparisons were performed with cross validation at sampling locations and assessed based on mean and root mean squared errors. The results revealed that maps developed using arsenic cokriging with iron have given the smallest error value and have shown closest fit to the extreme values in the dataset. Accordingly, arsenic cokriging with iron is believed to be a promising approach in mapping arsenic distributions in groundwater.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.
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