Investigation of the change in horizontal velocity gradient on the vertical axis caused by wave motion in vegetated areas

Ekolojik açıdan büyük önem arz eden sazlıklı bölgeler (sulak alanlar) hassas bir dengeye sahiptir. Özellikle göç eden kuşlar için önemli bir uğrak ve dinlenme yeri olan bu bölgeler, aynı zamanda içerdikleri zengin besin olanaklarıyla kara ve su canlıları için de önemli bir yaşam alanıdır. Bu bölgelerin korunabilmesi ve sürdürülebilir kullanımı için, mevcut hidrodinamik yapının bilinmesi gereklidir. Sazlıklı bölgelerde gerçekleştirilecek sıcak su deşarjlarıyla ortama eklenen atık suyun davranışının belirlenerek, olumsuz etkilerinin en aza indirilebilmesi bir gerekliliktir. Bu çalışmanın amacı sazlıklı ortama verilen sıcak su deşarjının dalga etkisiyle değişen hız dağılımının tespit edilmeye çalışılmasıdır. Bu amaçla, dalga yüksekliği, başlangıç sıcaklık farkı, deşarj edilen debi ve sazlık olup olmaması bağımsız değişken olarak kabul edilmiş ve bu şartlarda 17 adet kontrollü deney gerçekleştirilmiştir. Ölçülen parametreler; sıcaklık, hız, dalga yüksekliği ve dalga periyodudur. Deneysel çalışma 22×1×0.5 m boyutlarında bir kanalda gerçekleştirilmiştir. Akım hızları Vectrino+ akustik doppler hızölçer ile 50 Hz sıklığında kaydedilmiş ve en düşük kayıt süresi 1 dakika olarak belirlenmiştir. Sıcaklıklar Pt100 tipi 19 adet termometre ile ölçülmüştür. Sonuç olarak hem sazlıklı hem de sazlıksız ortamlar için dalga yüksekliği-hız dağılımı bağıntıları istatistiksel bir yaklaşımla elde edilmiştir. İstatistiksel yaklaşımda çoklu regresyon analiz yöntemi kullanılmıştır. Söz konusu bağıntılar bağıl sıcaklık, boyutsuz hız ve bağıl derinlik parametrelerinin fonksiyonları olarak verilmiştir. Elde edilen fonksiyonların istatistiksel açıdan yeterli hassasiyette olduğu görülmüştür. Sazlıksız ortamdaki hız değerleri klasik yöntemlerle hesaplandıktan sonra elde edilen bu fonksiyonlarla karşılaştırılarak sazlıklı ortamdaki dağılım elde edilebilmektedir. Anahtar Kelimeler: Sıcak su deşarjı, sazlıklı ortam, hız dağılımı. Ecologically important vegetated areas bear a tender equilibrium. These areas are specifically places for birds and the great habitats for animals as well, since these places are very wealthy when it comes to nutrients. Hydrodynamic structures of these places should be known in order to maintain a sustainable development. Thus, this study is done to reveal the hydrodynamic structures of vegetated areas and the behaviour of waste water with thermal water discharges, and eventually to reduce the negative effects of this phenomenon. The changes in the characteristics of thermal water discharges which are induced by vegetation at the receiving environment are examined with the help of an experimental study. Velocity and dispersion coefficients were tried to be determined with previously conducted studies. In addition, drift forces caused by the changes occurred in the flow by one plant or a plant group were tried to be determined. In this study, wave height, temperature difference, flow rate of the discharge, and the existence of vegetation are chosen as independent variables, and 17 sets of experiments are conducted. Temperature, velocity, wave height and wave period are the measured parameters during the experiments. Experiments are conducted in a 22×1×0.5 m dimensioned flume. Flow velocities are measured at least record is 1 minute long. Furthermore, temperatures are recorded with 19 "Pt100" type thermometers. As a result, a velocity dispersion function related to varying wave heights are derived with a statistical approach for vegetated and non-vegetated environments. Multiple regression method is used in the statistical approach and the aforementioned functions are given for the parameters which are relative temperature, dimensionless velocity and relative depth. Note that, multiple regression method was previously used for obtaining the dispersion coefficient and the flow conditions. The thermal water gradient affected by vegetation with respect to the mentioned variables was tried to be determined in the flow field.Excess temperatures for the vegetated experiments were chosen as 5 and 15 oC, where the flow rate was 15 l/min and the generated waves in the flume were 2.5, 5 and 7 cm of height for each temperature value. The experiments of non-vegetated case were carried out with the flow rate values; namely, 10 and 15 l/min for the same wave conditions. Recorded velocity values were divided by wave group velocity (H/T). Multiple regression analyses conducted for velocity are valid for the third and the fourth zone, if the temperatures of the first and the second zone are assumed to be constant. Consequently for the vegetated case experiments, the equation U/(H/T) =3.4457*z/zo - 0.00004*L - 0.0066 DT - 0.0329 Q was obtained as a result of the multiple regression analysis carried out for U/(H/T). And the result of the multiple regression analysis carried out for the non-vegetated case comes out with the equation U/(H/T) =2.7662*z/zo - 0.0001*L - 0.0080*DT - 0.0181*Q. The difference between these two equations reveals the change in the flow affected by the vegetation. This difference may be computed by a subtraction operation between these two equations which leads to the equation [U/(H/T)]s-[ U/(H/T)]= 0.6795 z/zo+ 0.00006*L + 0.0014*DT- 0.0148*Q. Here the index S expresses the result of the vegetated case experiment. The variables of the newly given equation come out as relative depth, horizontal distance, temperature difference between the receiving environment and the discharged fluid, and the flow rate of the discharge, all of which should already be known by any engineer who works on subjects related to thermal water discharge. Therefore, determination of the change in temperature and the velocity gradient becomes a simple issue. Note that, wave steepness and wave period are on the right hand side of the recommended equation (wave steepness is obtained by dividing significant wave height by significant wave period as known), and it is clear that if one knows the design wave height and wave period, it becomes possible to compute the vegetated case velocities after the determination of non-vegetated case velocities with the help of the given equations. Obtained results are valid for the scope and conditions of this study, and more general approaches should be produced by future studies on this issue. Specifically, investigating the effect of variation of the vegetation properties on the mentioned phenomenon can be recommended. Keywords: Thermal discharge, vegetation, velocity variation.

Experimental investigation of the effects of beach drainage on erosion in fine-grained beaches

Plajlar ince kumlardan iri kayalara kadar değişen büyüklükte kayaların birikmesiyle oluşmuş jeolojik bölgelerdir. Plajlar kara, hava ve deniz birleşiminde yer almakta olup morfolojileri dalga mekaniği, katı madde özellikleri ve mekaniği, plaj yeraltı suyu akımı ve mekaniği ile rüzgar etkilerinin etkileşimine bağlıdır. Sahil drenajı, sahil altına yerleştirilen perfore drenaj boruları vasıtasıyla dalga ve yeraltı sularının drene edilmesi ve böylece yeraltı su seviyesinin düşürülmesi ile sızma oranının arttırılması prensibine dayanır. Araştırmada ince taneli kuma sahip sahillerde sızma oranının arttırılması ile erozyonun nasıl değişeceği deneysel olarak incelenmiştir. Çalışmanın amacı değişik dalga özelliklerinin etkisinde drenaj borusunun farklı konumlarında profil şeklinin ve drenaj debisinin tayin edilmesidir. Bu amaçla fiziksel bir model geliştirilmiş ve basit analitik çözümler önerilmiştir. Bu çalışmalar daha sonra düzenli dalga koşullarında yapılan laboratuvar çalışmaları ile karşılaştırılmıştır. Drenaj debisinin tahmini, inşaa edilecek su toplama kuyusunun hesabında ve bu kuyudan suları denize deşarj edecek pompa kapasitesinin tayininde kullanılmaktadır. Öte yandan, değişik dalga ve drenaj borusu yerleşim yerleri için erozyon alanının tahmin edilmesi, kıyı duvarları ve kıyı kaplamaları gibi çeşitli yapıların stabilitelerinin belirlenmesi açısından önemlidir. Bu çalışmada hem drenaj debisi hem de erozyon alanı parametrelerinin tahmini için denklemler önerilmiştir. Sahil drenajı ile erozyon alanında azalma yaşanmıştır. Bunun nedeni olarak yer altı su seviyesinin düşmesi ile sızma oranında artma ve buna mukabil katı madde efektif ağırlığında artış söylenebilir. Profil verileri incelendiğinde erozyon alanındaki artışın en önemli nedeni ise dalga tırmanma yüksekliğinde yaşanan azalma görülmüştür.  Anahtar Kelimeler: Sahil drenajı, erozyon, stabilizasyon.Beaches play important roles in both the dissipation of wave energy and for the recreational purposes. They are generally in dynamic equilibrium. But, due to increasing industrial activities and population, human interference into the beaches occurs and the dynamic equilibrium deteriorates. In order to control the cross-shore and alongshore sediment transport in eroding beaches, some structures like breakwaters, groins, seawalls are constructed. These structures are composed of massive concrete blocks which lead to loss in aesthetic vision. Moreover, these structures are very difficult to relocate after construction. Beach drainage is an erosion control method studied in-situ, laboratory and numerically and offers an alternative to massive coastal control structures. Main philosophy lying under this method is lowering the water table and increasing the infiltration through the sediment matrix. As the infiltration rate increases, the probability of liquefaction and effective weight reduction of sediments will be reduced. Also, water that infiltrates during the wave runup will lead to reduction in flow velocity during both in runup and run-down phases. This reduction in flow velocity will lead to reduction in shear stresses. Recently, some numerical studies claim that for fine sediments, in case of infiltration, erosion occurs due to offshore migration of sediments. On the other hand, reports of in-situ investigations reveal that, in case of infiltration either the beach accretes or the erosion is reduced. Experiments are conducted in a narrow flume with 22m in length, 1m in width and 80cm in depth. Slope of beach profile is always kept constant (1:5), the profile and drainage flow rate data are measured.  The median grain size of the sediment is d50=0.3 mm. The diameter of the drainage pipe is 50mm and is laid all width of the flume. The pipe is perforated in 8mm holes to allow the water suction. Geotextile sheet is wrapped over the pipe to prevent the holes from sediment clogging. 6 drainage pipe locations are determined; beach profiles and drainage flow rates are measured in these locations. Between the beach head and the ground water trench, geotextile filter layer is placed to prevent clogging of the holes, which allow the ground water flow through the beach. Ground water level is always kept constant in all experiments as the same as the still water level. According to the experimental analysis, the waves which have lower height than 5.5 cm do not result in erosion in the profile in no-drain case. The area of the erosion is almost linearly increasing with wave height. In case of drainage, the wave height which does not result in erosion in the profile is observed as 8cm. Center of gravity of the offshore bar migrates landwards as the drainage pipe location approaches the intersection of beach profile and still water line. There is no direct relation between the drainage flow rate and erosion area. The important factor is that whether the runup/rundown wave water or the existing ground water is drained. The ground water is drained as the pipe location migrates landwards. According to the experimental analysis results, the most obvious reduction in the erosion area is observed when the pipe is placed in location (2). When the data measured in location (2) is compared with no-drain data, erosion area reduction rate is reduced when the wave height is increased. When the wave height is increased up to 25 cm, drainage has no advantage to reduce erosion Dimensionless drainage flow rate and dimensionless erosion area parameters are derived analytically by using the data measured in pipe locations of 1, 3, 4 and 5. Derived equations are verified by using locations 2 and 6. The increase in the infiltration rate by lowering the water table leads to reduction in the effective weight of the sediments and decrease in the flow velocity of the runup/rundown swash flows. When the profile graphs are investigated, the main reason for the erosion reduction should be the reduction of the wave runup height. Increase in the infiltration rate leads to reduction of the wave runup wave flow velocity and quantity, resulting in the decrease of runup limit of water waves. In the down-rush phase, the flow velocity is also reduced and the ability to carry sediments is decreased. Keywords: Beach drainage, dewatering, erosion, stabilisation

Beach profile response analysis during storm surges

Bu çalışmada, açıkta oluşan kum tepelerinin konumunun dalga özellikleri ve kıyıyı oluşturan malzemenin özellikleri cinsinden tanımlanması için fiziksel bir model geliştirilmiş ve dalganın kırılması ile harcanan enerji miktarı ile ilişkili basit analitik çözümler yapılmıştır. Bu çözümler daha sonra düzenli ve düzensiz dalga koşullarında yapılan labaratuvar çalışmaları ile karşılaştırılmış ve düzenli dalga ikliminde ortalama kök hatası 4.06%, düzensiz dalga ikliminde ise 6.21% olmuştur. Bütün bu çalışmalar dalganın kırılma-sından sonra katı madde taşınımı için gerekli olan birim hacimdeki enerji miktarının, dalganın kırıldığı anda birim hacimde açığa çıkan enerji miktarı ile profilin denge halinde olabilmesi için gerekli olan enerji miktarı arasındaki farka eşit olduğunu göstermiştir.  Anahtar Kelimeler: Bar oluşumu, dalga yüksekliği, dinamik stabilite, katı madde, kıyı profili.During winter seasons, an increase in wave height and decrease in wave period grounds erosion of foreshore coastal regions where eroded material accumulate at some distance offshore from the coast forming an offshore bar. Knowledge of the characteristics of an offshore bar under wave attack is of great importance in a number of coastal engineering problems particularly in coastal erosion problems. The goal of this investigation is development of a physical model to predict the actual location of offshore bar in terms of wave climates and sediment properties of beach profiles. For this purpose, a simple analytical solution based on energy dissipation relation is developed. The method presented is compared with experimental results where root mean square of 4.06% and 6.21% for regular and irregular waves respectively achieved. Throughout the research, based on dynamic equilibrium profile considerations, the energy required for sediment transport due to wave breaking per unit volume, is expressed in terms of the difference between the actual, and equilibrium levels of wave energy dissipations per unit volume. During experimental studies it is observed that when the wave height increases, the bar formation migrates further offshore progressively, increasing the volume until the equilibrium bar volume is attained.  Keywords: Bar formation, beach profile, dynamic stability, sediments, wave height

Effect of singular vegetative elements on open channel flow characteristics

Son yirmi yıldır artan çevre bilinci ile birlikte akarsu yatağındaki bitkilerin akım alanı üzerine etkisini araştıran çalışmalara olan ilgi oldukça artmıştır. Farklı türde bitki topluluklarının akım alanı üzerine etkisini araştıran pek çok araştırma yapılmış olmasına rağmen geniş gövdeli tekil ağaçlar gibi bitki türlerinin akım alanı üzerine etkisi henüz yeterince anlaşılmış değildir. Bu çalışmada bir akım ortamındaki tekil doğal bitkilerin akımın hız ve türbülans karakteristikleri üzerine etkisini araştırmayı amaçlayan iki boyutlu deneyler gerçekleştirilmiştir. Deneylerin tamamı 26 m uzunluğunda, 0.98 m genişliğinde ve 0.85 m derinliğindeki akım kanalında gerçek bitki fidanları kullanılarak gerçekleştirilmiştir. Taşkın yataklarında sıkça rastlanan bu doğa olayını analiz etmek amacıyla, geniş gövdeli ağaçlar hacim yükseklik değişimleri gözönüne alınarak başlıca üç sınıfa ayrılmıştır. Hız ölçümlerinde üç adet akustik Doppler hız ölçer kullanılmıştır. Analiz aşamasında akım doğrultusundaki ve düşeydeki zamansal ortalama hız bileşenleri, akım doğrultusundaki ve düşeydeki türbülans bileşenleri ve türbülans kinetik enerjileri araştırılmıştır. Buna ilave olarak bitkinin mansab tarafında, bitkiden belirli bir mesafede, bitkinin yapısal özelliklerinin bir fonksiyonu olarak hız profilini veren bir eşitlik elde edilmiştir. Elde edilen eşitliğin geçerliliği deney verileri aracılığı ile sınanmıştır. Ayrıca, deneyler sonucunda geçirimli yapılarına rağmen akım ortamındaki bitkilerin akımı kayda değer ölçüde etkilediği ve neden oldukları türbülans ile önemli miktarda enerjiyi kırdıkları görülmüştür. Anahtar Kelimeler: Açık kanal, hidrolik, bitki, taşkın yatağı, hız profili.In the last two decades with the increasing environment awareness there is a growing interest on studies which attempt to understand the impact of vegetation on flow field in river and flood plain systems. Although in the past great attention has been devoted to explore the impact of vegetation community on flow pattern, the effect of singular vegetative element, such as trees with large trunk, on flow and turbulence pattern is not yet known. The primary aim of the study was to explore the impact of presence of natural singular vegetative elements (trees with large trunk) in flood plains on velocity and turbulence characteristics. In order to achieve the objective stated above two dimensional experimental measurements were conducted in controlled laboratory conditions. All the experiments were performed in the flume, which is capable of supplying steady flow and regular wave, located in Hydraulic Laboratory of Istanbul Technical University. The size of the flume is 26 m in length, 0.98 m in width and 0.85 m in depth.  Tree saplings were utilized to represent the vegetative effect on flow field. In order to analyze this commonly observed nature phenomenon, trees with large trunk were classified into three groups on the basis of their volume versus height relation. The primary difference between those introduced three types was the volume increment gradient along the height. For given successive height intervals, the volume of vegetation pertain to any interval is always larger than the volume of the interval belong to the one closer to bed for Type 1, approximately constant for Type 2, smaller for Type 3. In nature, since each species is unique in terms of architectural and structural properties, three representative species were selected which could characterize those three types mentioned above. Those selected species were Pinus Pinea, Thuja Orientalis, and Cupressus Macrocarpa for Type 1, Type 2 and Type 3, respectively. Throughout the velocity measurements three Acoustic Doppler Velocimeters, two with maximum 200 Hz sampling frequency, one with maximum 25 Hz sampling frequency, were employed. During the data analysis in order to further understand of the impact of presence of vegetation on flow, the time averaged velocity and turbulence kinetic energy characteristics were examined. The experiments that aim to examine the  More specifically, the experiments on velocity profile measurements along the flume were planned to be run for the combination of 2 depth values, 5 discharge values and 3 vegetation species. At the 10 locations velocity profiles were obtained by measurements along the centerline of the flume at the downstream of vegetation. In overall, 15 velocity profiles were acquired for each test condition. At the design stage of some water resources projects, estimating the flow conditions in open channels with an adequate accuracy is important. However, the gap was detected in the literature that there is still no any method or formulation which gives the velocity profile at the downstream of vegetation depending on the vegetative characteristics. In this context, it was considered that generating a formulation which gives the velocity profile at the downstream of vegetation is necessary for river engineers. Based on these facts a formulation which gives the velocity profile at a certain distance from vegetation was introduced. The validity of the proposed formulation was tested with experimental data for verification. It was seen that the velocity results obtained by introduced formulation are in well agreement with the experimental data. It should be kept in mind that the formulation is a function of vegetative characteristics such as volume, projected area, and submergence degree. Hence approximate calculation of the volume of related vegetation in the field with acceptable accuracy is crucial for the success of the application. The similarity between whole vegetation and its branch of related vegetation can be employed as a reference during the calculation of volume of vegetation. Experimental findings revealed that despite their porous structures, the presence of vegetation considerably disturbs the flow field and dissipate a remarkable amount of energy by turbulence. Furthermore experiments showed that sub-canopy flow occurs for three types of vegetation at the downstream of vegetation in the region close to bed. With increasing compactness of vegetation the magnitude of sub-canopy flow increases. In overall assessment it was concluded that presence of any type of tree with large trunk leads to 0-70 % extra sub-canopy flow at the bottom; 30-110 % retaining effect in the region close to the water surface.Keywords: Open channel, hydraulics, vegetation, flood plain, velocity profile

Alüminyum yüzey işleme endüstrisi proses atıksularından elektrokoagülasyon yöntemiyle florür giderimi

Fluoride concentration higher than 4 mg/L creates several dental problems and decompositions in the skeletal structure. Daily intake of 6 mg fluoride may cause articulation diseases, weight losses and bone breakages. Therefore, fluoride concentration in drinking water has been strictly regulated as a maximum value of 1.5 mg/L by Turkish Standards Institute (TSE), World Health Organization (WHO) and European Commission (EC). Owing to its high toxicity, legal authorities have established the discharges standards for fluoride from wastewater treatment plants. Therefore, the increasing demand for the control of fluoride being released from industrial activities has led to the search of more effective treatment methods for fluoride bearing effluents. Although, several physico-chemical treatment methods such as adsorption using different types of adsorbents such as activated alumina, activated carbon, fly ash etc., coagulation with alum, chemical precipitation with lime, and electrocoagulation using aluminum electrodes have been addressed for removal of fluoride from the samples bearing moderately low amount of fluoride in the related literature. Among these treatment processes, electrocoagulation (EC) is deemed a promising one in removing fluoride from industrial effluents. The target of the present study is to examine the treatability of an aluminum surface treatment effluent bearing high amount of fluoride by EC with aluminum electrodes and to explore the effect of varying operating parameters such as the applied current density, initial pH, and electrolyte (NaCl) concentration on fluoride abatement as well as organic matter removal and aluminum reduction. In order to assess the effects of the operation parameters on process performance and to determine the optimum operation conditions in terms of removal efficiencies, a detailed experimental study was performed using composite samples taken from an aluminum surface treatment process. An aluminum surface treatment effluent bearing high amount of fluoride (3180-6490 mg/L) and aluminum (2695-4690 mg/L) together with organic matter (485-750 mg/L) was used in the experimental study. NaCl was selected as an electrolyte because of high efficiency on EC. The electrocoagulator consisted of a 10 L-capacity polyethylene reactor equipped with 4 pairs of anodes and cathodes made of aluminum. The process performence was followed by COD, fluoride, and aluminum. In order to determine the effect of the applied current density on EC process performance a wide range of the applied current density varying between 3.7 and 18.6 mA/cm2 was applied at an electrolyte concentration of 500 mg NaCl/L and at original pH of sample (2.52). The results indicated that increasing the applied current density improved fluoride removal efficiencies. Nevertheless, this improvement in fluoride removal was observed after 30 minutes of operation time. In these experiments commenced at an initial pH of 2.52, solution pH gradually increased and reached to ~6.0. The lowest remaining aluminum concentration was obtained at the end of EC process performed at the highest applied current density. The results obtained at EC applications run at an initial pH of 2.54, a high NaCl concentration of 1500 mg/L, and at a wide range of applied current density varying between 3.7 and 29.8 mA/cm2 indicated that increasing the applied current density increased fluoride and aluminum abatement efficiencies and shortened the reaction time. Similar to EC runs conducted at 500 mg NaCl/L solution pHs gradually increased up to 6.0 during these EC applications. Up to 40% COD removal efficiencies were obtained at the end of these EC applications. The effect of electrolyte concentration and initial pH on process performance was investigated at an applied current density of 18.6 mA/cm2 for an NaCl concentrations of 1500 and  3000 mg/L  and at initial pHs of 2.52 and 3.8. EC performed at initial pH of 3.8 yielded better fluoride abatements and aluminum reductions than EC run at original pH of 2.52.While an increase in electrolyte (NaCl) concentration from 1500 to 3000 mg/L slightly enhanced removal efficiencies at the beginning of EC operation, almost the same fluoride abatements as well as COD and aluminum reductions were obtained at the end of 180 minute EC operation. In the present study, the electrocoagulation using aluminum electrodes proved to be a promising treatment method for fluoride removal as well as aluminum and organic matter reductions from an aluminum surface treatment effluent bearing high amount of fluoride and aluminum. Keywords: Aluminum, aluminum surface process, aluminum electrode, electrocoagulation, fluoride.Bu çalışmada, yüksek florür içeriğine sahip atıksuları temsil etmek üzere, alüminyum yüzey işleme endüstrisinden alınan numuneler üzerinde, elektrokoagülasyon (E.K.) prosesi ile florür ve diğer kirleticilerin giderimi ile ilgili deneysel çalışmalar yürütülmüştür. Alüminyum yüzey işleme endüstrisi proseslerinden alüminyum yüzey temizleme ve durulama banyosundan alınan atıksu numuneleri hacimsel olarak 1:1 oranında homojen bir şekilde karıştırılarak kompozit numuneler hazırlanmıştır. Alüminyum yüzey temizleme banyosunda sırasıyla %19, %8.5 oranında hidroflorik asit ve fosforik asit ile birlikte tensit (noniyonik) kullanımından dolayı, pH’sı düşük, florür, alüminyum ve KOİ konsantrasyonu yüksek atıksular meydana gelmektedir. Bu atıksuların arıtımı gerek florür gerekse alüminyum ve KOİ değerlerinin alıcı ortam deşarj standartlarını sağlayabilmesi açısından önem kazanmaktadır. Deneysel çalışmalarda E.K. uygulamalarında işletme parametrelerinin proses performansı üzerine etkileri incelenmiştir. İşletme parametreleri olarak, akım yoğunluğu, elektrolit olarak kullanılan NaCl konsantrasyonu ve pH ele alınmıştır. Ham kompozit numuneler üzerinde uygulanan E.K. denemelerinde artan akım yoğunluğu ve zamana bağlı olarak florür için yaklaşık %97 giderim verimi elde edildiği, artan akım yoğunluğu ve NaCl konsantrasyonuna bağlı olarak alüminyum gideriminde yüksek giderim verimlerine ulaşılabildiği ancak organik maddeyi temsil eden KOİ gideriminin ise %40 civarında kaldığı tespit edilmiştir. Deneysel çalışmaların sonucu olarak ham numunelerin E.K. prosesi ile gideriminde florür, alüminyum ve KOİ parametreleri için alıcı ortam deşarj standartlarının sağlanamadığı tespit edilmiştir. Anahtar Kelimeler: Alüminyum, alüminyum yüzey işleme, alüminyum elektrod, elektrokoagülasyon florür

Effect of chelating agents on reactive dyebaths color removal with high pH ozone oxidation

Bu çalışmada, tekstil endüstrisinde yaygın olarak kullanılan reaktif boyar maddelerden Procion Navy HEXL ile boyama proseslerinde iyon tutucu olarak kullanılan EDTA ve EDTMPA’nın yüksek pH'da ozon ile renk ve organik madde giderimi üzerine etkileri deneysel olarak incelenmiş ve anılan iyon tutucuların ortamda ayrı ayrı ve Procion Navy HEXL ile birlikte bulunmaları durumunda oksidasyon karakterindeki değişimleri karşılaştırmalı olarak değerlendirilmiştir. 15 dakikalık reaksiyon süresi sonunda %72 KOİ giderim verimi elde edilmiş ve rengin tamamına yakını giderilmiştir. EDTMPA ve EDTA'nın ortamda tekil olarak bulunmaları durumunda 90 dakikalık ozonlama sonunda, EDTMPA ve EDTA için sırasıyla 2.81 ve 3.32 mg O3/mg giderilen KOİ ozon tüketim oranında, % 80 ve % 43 KOİ giderim verimleri elde edilmiştir. Boyar madde ve iyon tutucuların ortamda tekil ve birlikte bulunmaları durumunda organik maddenin ozon ile oksidasyonun görünür birinci derece reaksiyon kinetiğine uyum sağladığı belirlenmiştir. Elde edilen KOİ giderim hızları EDTMPA'nın (0.0291 1/dak) EDTA ya (0.0258 1/dak) nazaran daha hızlı okside olduğunu göstermiştir. Yüksek pH’da boyar maddenin ortamda EDTA ile birlikte bulunması durumunda 90 dakikalık reaksiyon süresi sonunda % 78 lik KOİ giderimi 2.88 mg O3/mg giderilen KOİ ozon tüketim oranında gerçekleşmiştir. Ortamda boyar madde ve EDTMPA’nın beraber bulunması durumunda ise bu değerler sırası ile % 90 ve 2.40 mg O3/mg giderilen KOİ olarak bulunmuştur. İyon tutucunun boyar maddenin kromofor grubunun oksidasyonu engellenmediği ancak bu grubun aynı seviyede oksidasyonu için gerekli süreyi uzattığı tespit edilmiştir. Aminopolikarboksilat yapısına sahip ve iyon tutucu olarak kullanılan yardımcı kimyasal maddelerin renk giderim hızını, fosfonik asit yapısına sahip iyon tutuculara nazaran daha fazla yavaşlattığı saptanmıştır. Anahtar Kelimeler: Boya banyoları yardımcı kimyasalları, EDTA, EDTMPA, reaktif boya banyoları, renk ve organik madde giderimi, tekstil endüstrisi, yüksek pH'da ozon ile oksidasyon.Color is one of the characteristic parameters of textile industry wastewaters. Although there are several physical-chemical methods applied for color removal such as adsorption, membrane processes and chemical oxidation, chemical oxidation has become the method of choice due to its high efficiency and ease of operation. Ozone is one of the most effective oxidant used for this purpose. Ozone oxidation of textile industry wastewaters, spent and simulated dye baths has been a focus of investigations (Davis et al., 1982; Grau, 1991; Carriére et al., 1993; Namboodri et al., 1994a,b). Mechanism and kinetics of ozonation of synthetic dye solutions were also extensively studied (Snider and Porter,1974; Perkins et al., 1980; Teramoto et al., 1981; Perkins et al., 1995). Actual dye baths involve the use of several assisting chemicals in addition to dyes. Basic chemicals used in reactive dyeing are NaCl, Na2CO3 and sequestering agents. NaCl is used to facilitate diffusion of the dye to the fiber. Na2CO3 mostly has a dual purpose: it helps the fixing of the dye and increasing and buffering the pH. Sequestering agents are chelate forming ligands that bind the metal ions such as Cu2+, Fe2+, and prevent their interference with dye. Kabdaşlı et al. (2002) studied the effect of assisting chemicals in the dye bath on ozonation of dyestuffs. They found out that sequestering agents exerted a significant effect on the ozone oxidation of the dye by reducing the reaction rate and increasing the amount of ozone being used, while NaCl and Na2CO3 had negligible effect on color removal. Commonly used conventional sequestering agents such as NTA (nitrilo triacetic acid) and EDTA (ethylenediamine tetraacetic acid) contain aminopolycarboxylate groups. Recently a new generation sequestering agents that are based on phosphonic acid derivatives has been introduced. The advantage of these compounds in addition to their capability of strongly binding the metal ions, is their stability at high temperatures employed in reactive dyeing. The study aimed to asses several aspects of oxidation dye bath assisting chemical, by ozonation emphasizing their effect on decolorization at high pH. In the first stage of experiments dyestuff and chelating agents were separately oxidized by ozone at high pH. In the second stage, oxidation of the combination of dyestuff and chelating agent was carried out. The dyestuff used in the experiments was Procion brand Navy HEXL that involved the bifunctional group bis(amino chlorotriazine) and have been frequently used for dyeing cellulosic fibers. The chelating agents selected were, EDTA which has been used commonly as a conventional sequestering agent and a new generation sequestering agents EDTMPA (ethylenediamine tetramethylene phosphonic acid) which has been actually used in textile dyeing and had a similar structure to EDTA. EDTA and EDTMPA concentrations were selected considering the actual concentrations used in the reactive dye baths. Oxidation experiments were conducted at pH 10.5 which was also reflected the actual pH of the spent dye bath. Oxidation of the Procion Navy HEXL was relatively fast providing over 50 % color removal in 3 minutes and reaching almost complete removal in 10 minutes. COD removal efficiency was 72% at the end of the 15 minute reaction time. At the end of the experiment a specific ozone consumption of 0.8 mg O3 /mg COD removed was determined. The evaluation of the single dye ozonation results showed that pseudo-first order kinetic expression was applicable with respect to the COD. 80 % and 43 % COD removal efficiencies were obtained in 90 minutes by the ozonation of 2.293 mM EDTMPA and EDTA solutions respectively. The ozone utilization ratios were of 2.8132 mg O3/mg COD removed for EDTMPA and 3.32 mg O3/mg COD removed for EDTA at the end of the oxidation period. The evaluation of the results showed that pseudo-first order kinetic was also applicable for the oxidation of selected chelating agents with respect to COD. The rate constants were 0.0291 and 0.0258 1/min for EDTMPA and EDTA respectively. As can be seen from the results it can be concluded that EDTMPA could oxidize more rapidly than EDTA. Results of ozone oxidation of combination of the dye and chelating agents at pH 10.5 showed that when they were existed together oxidation rate of both reduced. The same degree of color removal (below 100 Pt-Co) was obtained in 30 minutes for EDTMPA and 60 minutes for EDTA versus 10 minutes when dye existed singly. COD removal characteristics of the systems were also modified when the dye and chelating agents existed in combination as well as pseudo-first order reaction rates. Keywords: Color and organic matter removal, dye bath additive, EDTA, EDTMPA, high pH ozonation, reactive dye baths, textile industry

Hydrodynamic modeling of Beysehir Lake for 1998 water year

Bu çalışmada, Beyşehir Gölü’nün üç boyutlu hidrodinamik modeli kurulmuştur. Beyşehir Gölü Türkiye’nin en büyük tatlısu gölüdür. Kurulan hidrodinamik model; 1992-2001 su yıllarının ortalama akımlarını en iyi temsil eden 1998 su yılı için çalıştırılmıştır. Modelleme çalışmasında; Devlet Su İşleri’nden (DSİ) meteoroloji, hidroloji ve batimetri verileri, Elektrik İşleri Etüt İdaresi’nden (EİE) hidroloji ve Devlet Meteoroloji İşleri’nden (DMİ) de meteoroloji verileri günlük olarak temin edilmiştir. Bu çalışmada ELCOM (Estuary and Lake Computer Model) 3D modeli kullanılmıştır. Modele girdi olarak; günlük rüzgâr hızı, rüzgâr yönü, kısa dalga radyasyonu, hava sıcaklığı, bulutluluk oranı, nemlilik, hava basıncı, yağış, giren / çıkan akarsuların debileri ve giren / çıkan akışkanının su sıcaklığı verilmiştir. Ayrıca gölün batimetrisi modele, planda 103x85 ve düşeyde 10 parçaya ayrılarak oluşturulan 87550 grid yardımıyla dijital olarak tanımlanmaktadır. Model; sonlu hacimler metodu ile hesap yapmaktadır. Modelin çıktıları; su sıcaklığı ile akışkanın x, y ve z yönündeki hızlarıdır. Model sonuçlarını daha iyi analiz etmek amacıyla yazar tarafından Matlab dilinde programcıklar yazılmış ve bu programlar kullanılarak model sonuçları detaylı olarak irdelenmiştir. Modelden elde edilen su sıcaklık değerleri ile DSİ tarafından yapılan arazi ölçümleri kıyaslanmış, modelin yeterli doğrulukta olduğu gösterilmiştir. Kurulan model yardımıyla, göldeki su hareketi ve bu su hareketlerine etki eden parametreler belirlenmiştir. Ayrıca gölde modellenen hidrodinamik olayların yıl içi değişimi özetlenmiştir.  Anahtar Kelimeler: Beyşehir Gölü, hidrodinamik modelleme, ELCOM 3D, göl yönetimi. In this study the hydrodynamic model of Beysehir Lake is established. The prepared three dimensional hydrodynamic model is run for an average one year long period (1998 water year). In addition this paper includes the basic equations and modeling techniques used in the modeling studies. The model considers the pressure, air temperature, the turning effect of the earth, the tide force, the saltiness, the wind force, and the surface heat exchanges, the effects of the incoming and outcoming rivers. In the modeling study; the meteorological, hydrological and bathymetry data is provided by DSI whereas EIE delivered the hydrological data and DMI the meteorological data. As inputs for the model simulations; wind speed, wind direction, short wave radiation, air temperature, cloudiness,  humidity, air pressure, precipitation, in-and outflow discharges are considered in daily basis together with the digital bathymetry of the lake. The model is defined in the three dimensional cells. In the plan view from the top side there are 85 and 103 sections, horizontally and vertically, respectively. The lake is divided into 10 sections in depth; 8755 (85*103 = 8755) cells are formed and divided in the program. The selected grid dimensions satisfy the Courant-Friedrichs-Lewy (CFL) condition. The time interval is selected as 3600 seconds. The solution duration of the model becomes longer in case of decreasing the time interval and increasing the grid number. The longest river reaching the Beysehir Lake is the Sarisu River with Number 19-104. This river had the highest discharge on 30 March 1998 (10.5 m3/s). The discharge entries do not affect the lake in general. The mixtures are in the local level even for high discharge entries. The minimum and maximum water temperature differences obtained from the run of the program for the 1998 water year are shown in Figure 2. The stratification clearness is high parallel to the increase in the difference between maximum and minimum temperatures. Either water motions or stratification occurs because of the density difference caused by the water temperature change on the lake. For example, the stratification increases if the water in the upper layer cools and causes to a mixture if it gets warmer. These mixtures and stratifications may occur both horizontally and vertically. With the help of the model, the water motions on the lake and the parameters affecting the water motion have been determined. Besides, the change of the hydrodynamic events on the annual basis has been summarized.  The elements which form a lake, their characteristics, and the parameters affecting these elements are summarized. The loops in the lake, the stratification and the characteristics of the mixture are explained, the affecting external parameters are defined and the basic connections between them are presented. The validation tests are applied to the models and it is shown that the fit between the model and the data is sufficiently well. In addition the parameters effective in the models are investigated and their affects are summarized. The water temperatures obtained from the model are compared with the water temperatures measured by DSI. This comparison is presented in Figure 7. If the R2 value obtained by Equation 4 is close to 1 then the model results are close to the observed values (Bayazıt, 1996). In this study R2 value is found as 0.956. The results obtained can be summarized as follows: - The opposite stratification occurring in the winter is quite obvious, The stratification in the summer months is relatively weak, Beysehir Lake is a dimictic lake,The first three parameters affecting the model are; the precipitation, moisture and wind velocity,The river entries and the discharge abstractions are not effective in the whole lake,The shallow sections of the lake reacts with the external affects in a shorter duration, i.e. the changes in the air temperature cause the warming or cooling of the water. So vertical stratification occurs in the lake.  Keywords: Lake Beysehir, hydrodynamic modeling, ELCOM 3D, lake management.&nbsp

Experimental investigations on tsunami runup height on permeable beachs

Tsunamiler depremlerle tetiklenebilen zemin hareketleri, heyelanlar, kayma, göçme, çökme gibi olaylar ile oluşabilmektedir. Bu dalgalar kıyı batimetrisindeki değişimle birlikte iç kısımlara doğru ilerleyerek büyük hasarlara neden olurlar. Tsunamiler özellikle kıyı çizgisinde tırmanma bölgesinde daha etkili olduğu için tırmanma yüksekliğinin önceden tahmin edilebilmesi kıyı yapılarının boyutlandırılması açısından önemli olacaktır. Bu çalışmada tsunaminin geçirimli yüzeylerde tırmanma yüksekliği deneysel olarak incelenmiştir. 1:5 eğimde geçirimsiz yüzey pürüzsüz, düz saç levha kullanılarak oluşturulmuştur. Aynı eğimde geçirimli yüzey için dane çapı 0.35 mm ve birim hacim ağırlığı 2.63 gr/cm3 olan doğal plaj malzemesi kullanılmıştır. Tırmanma yüksekliğine etki eden parametreler dalga yüksekliği, şev eğimi, su derinliği, eğimi oluşturan malzeme özellikleri olarak belirlenmiş geçirimli yüzeyler için ampirik bir  ifade önerilmiştir.Anahtar Kelimeler: Tsunami, tırmanma yüksekliği, geçirimli kıyı, deney,eğimli kıyı, kum.Tsunamis may be generated by earthquake-triggered movement of the sea bottom, landslides and collapses. With the change of nearshore bathymetry these waves progress towards inland and causes large damage. Prediction of runup height will play an important role in dimensioning coastal structure as tsunamis are more effective in the runup area at the shoreline. In the literature research on runup height, tsunami wave is liken to solitary wave and produced by horizontal movement of a vertical plate, which is a proposed by Goring (1978). In this study, for the simulation of sudden motion of the ocean bottom, tsunami wave generation system is developed by piston attached to an horizontal plate. The piston moves vertically. Experiments were carried out in the glass-side wall wave flume of 22.5 m length, 1 m width, and 0.50 m depth at the Hydraulics Laboratory, Civil Engineering Faculty, Istanbul Technical University. The beach was formed by natural beach sand and had a slope of 1 vertical to 5 horizontal. The specific gravity of sand was 2.63 g/cm3 and the diameter of sand was 0.35 mm. In the experiments it is observed that the waves are not broken. Water surface profiles and velocity values of the waves calculated and generated are compared. Runup height of tsunami waves on permeable beach is analysed and the experimental results, for impermeable slopes are compared with the runup law and it is seen that they are in consistency. Empirical equation are proposed for permeable beach by defining parameters effecting runup height, wave height, slope, water depth, and the characteristics of the material at the slopes. Keywords: Tsunami, run-up height, permeable beach, experiment, slope beach, sand

Performance modification of vertical faced coastal structures under waves

A sloped face maintained with "rubble-mound" technique, is mostly preferred as far as the coastal structures that are designed and constructed in order to be protected against wave effects are concerned. The main reason is not only the inexpensive and easy handling of rubble-mound operation, but also the satisfactory dissipation of incident waves on this sloped face, decreasing both the dynamic load and the reflected component. The vertical faced coastal structures, on the other side, can be constructed to fulfill many different functions with their constant breadth and suitable draft that can be used both for berthing and handling purposes. However, the vertical faced structures are poor to dissipate reflection or to limit wave run-up, compared to sloped ones, at the same time being exposed to high wave loads especially if they are plain faced. There have been several studies devoted to neutralize these disadvantages and managed to increase the performance of vertical faced structures by means of newly developed front face configurations. On the axis of this very same effort, the main goal of this study is to come up with an optimized structure configuration which will not bring a significant extra cost and will be easy to construct and mount; yet, at the same time which is capable of decreasing wave reflection, wave run-up and wave loads reliably with its high dissipation performance. First, various modifications proposed during past studies for vertical faced coastal structures were gone through. Several theoretical and experimental studies conducted on different variations of chambered breakwaters with a perforated front face have yielded quite satisfactory performance against waves, on the condition that the structure is dimensioned and designed with respect to that specific wave. These breakwaters, called "Jarlan" type after the first one to propose, may give a decreasing performance if incident wave period does not coincide with the resonance properties of their chambers. The partially perforated double chambered structure which is proposed with this study, is able to damp the wave energy with its upper chamber located just above the mean water level, without any strong dependence on the incident wave period, while performing the resonant dissipation to a specific wave frequency with its very shallow lower chamber separated from the upper chamber with a slab-like panel resting at the mean sea level. A plexiglas model of this structure, called as the flow chambered caisson, were manufactured with adjustable chamber breadths and tested under 9 sets of regular and one set of irregular waves, for different frontface perforation ratios and different relative dimensions. All the related performance parameters were derived as dimensionless parameters in order to be valid in any system and both in model and prototype scales. These parameters are reflection and runup coefficients for wave damping; pressure coefficient, force and moment coefficients for dynamic wave loads. The results of physical modeling study were compared to the performance of an equivalent plain vertical structure, tested under control experiments. Theoretical values for wave loads were also calculated in order to make further comparison with experimental results. The method proposed by Goda (1985) for wave load calculation on a vertical structure was employed and all calculated values were converted to the defined dimensionless ones. Experimental data implies that, flow chambered caisson can decrease the reflection coefficients down to 0.1 and  0.5 respectively for regular and irregular waves; also the horizontal wave force and wave moment were measured to be 25% to 35% less than the ones measured/calculated for an equivalent plain vertical faced structure. As a result, it was tried to picture an optimum structural configuration as a front faced coastal structure with its easy construction and handling with no significant extra cost; that can not only be used for port-functional purposes like quays, but also can be constructed as a breakwater in order to protect the coastal region/facility. The resulting flow chambered caisson structure is believed to satisfy these criteria to a significant degree, if a prototype application of this structure is constructed after the case-specific design is optimized with further laboratory experiments. It should be noted that open mindedness of decision makers is a prerequisite in order to achieve more developed and advanced engineering structures. Keywords: Upright coastal structures, perforated breakwaters, physical modelling, wave dissipation, wave loads.Bu çalışmada eğimli kıyı yapılarına göre daha yüksek yansıma, daha yüksek tırmanma ve daha yüksek dalga yükleri ortaya çıkaran düşey yüzlü kıyı yapılarının, sayılan bu dezavantajlarının azaltılabilmesi amacıyla geliştirilmiş bir önyüz konfigürasyonu tanımlanmış, bu özelliklerdeki bir yapı için imal edilen fiziksel model üzerinde düzenli ve düzensiz dalgalarla deneyler gerçekleştirilmiştir. Önerilen bu yapı akım odacıklı keson olarak adlandırılmıştır ve tam sakin su seviyesinde bir levha ile ayrılmış iki sığ odacığı bulunan kısmi delikli önyüze sahip bir keson formundadır. Deney sonuçlarına göre dalga yansıması, tırmanması ve dinamik dalga yükleri boyutsuz parametreler cinsinden ifade edilerek yapının performansı değerlendirilmiştir. Bu sonuçlara göre, yapının yansıma katsayısı düzenli dalgalarda 0.1 düzensiz dalgalarda da 0.5 değerlerinin altına kadar inmiştir. Ayrıca boyutsuz olarak türetilen dalga itkisi ve dinamik dalga momentinin, eşdeğer bir düz düşey yüzeyli yapıya göre bu gelişmiş yapıda % 35~% 25 mertebesinde azaltılabildiği görülmüştür. Bulunan deneysel sonuçlara ve yapılan gözlemlere göre, önerilen yapının oldukça etkili biçimde gelen dalganın enerjisini sönümleyebildiği sonucuna varılmıştır. Bunun yanında, önerilen keson sadece belli bir periyottaki gelen dalgayı değil, üst odacığı sayesinde oldukça geniş bir periyot aralığındaki dalgaları sönümleyebilmektedir. Bu noktada üst odacık genişliği yeteri kadar uzun seçilirse, yalnızca düz düşey yüzlü yapılara kıyasla değil, dalgayı odacığı içindeki rezonans özellikleriyle sönümleyen klasik tipteki perfore dalgakıranlara göre de daha avantajlı bir yapı elde edilebilmektedir. Anahtar Kelimeler: Düşey yüzlü kıyı yapıları, perfore dalgakıranlar, fiziksel modelleme