Investigation of sea level trends and the effect of the north atlantic oscillation (NAO) on the black sea and the eastern mediterranean sea

The North Atlantic Oscillation (NAO) has significant effects on sea levels, weather, and climate. In this study, the sea level trends and the effects of the North Atlantic Oscillation Indices (NAOI) on annual mean sea level data were assessed for the Black Sea and the Eastern Mediterranean Sea. The trends of sea level and NAOI were determined using Mann-Kendall dimensionless z statistics. Generally, upward sea level trends were detected for the Black Sea and the Eastern Mediterranean Sea. In the Black Sea, significant and continuous upward trends were detected after the year 1950. Weaker trends were detected for the Eastern part of the Mediterranean Sea. Sea level trends were correlated with trends in NAO indices; negative correlations were detected for the Black Sea, whereas positive correlations were found for the Eastern Mediterranean Sea. Paired t tests were performed to determine the turning points for all sea level data sets. The value of t was positive for all data sets, which means that the mean value of the data set before the turning point was smaller than the mean value of the data set after the turning point

Dispersivite değerlerinin homojen ve heterojen gözenekli ortamlarda deneyler yardımıyla belirlenmesi

Bu çalışmada hem homojen hem de heterojen gözenekli ortamlarda kirliliğin taşınmasını araştırmak için Dokuz Eylül Üniversitesi Mühendislik Fakültesi İnşaat Mühendisliği Bölümü Hidrolik Laboratuarında kapsamlı bir deney sistemi tasarlanmış ve inşa edilmiştir. Yeraltısuyunda kirliliğin yayılmasında önemli bir rol oynayan dispersivite değerleri homojen ve heterojen ortamların her ikisi için üç boyutlu yeraltısuyu akımı durumunda deneysel olarak belirlenmişlerdir. İnşaat Mühendisliği Bölümü Hidrolik Laboratuarında 12 m uzunluğunda, 135 cm genişliğinde ve 60 cm yüksekliğinde yerden 70 cm yukarıda bir kanal inşa edilmiştir. Kanaldaki gözenekli ortamlar farklı boyutlarda kumlar vasıtasıyla oluşturulmuş ve izleyici deneyleri kirletici olarak NaCl kullanılarak gerçekleştirilmiştir. Değişik doğrultulardaki konsantrasyonlar ölçülmüş ve dağılımları belirlenmiştir. Buna bağlı olarak akım boyunca ve akıma dik yönlerdeki dispersivite değerleri deneme yanılma yöntemi ilgili teorik bağıntılara uygulanarak Mass Transport 3 Dimensional (MT3DMS) yazılımının kullanımıyla belirlenmiştir. Heterojen ortam farklı daneli malzemeler içeren üç yatay tabakayla oluşturulmuştur. Konsantrasyon dağılımı gözlenmiş ve dispersivite değerleri adveksiyon-dispersiyon denklemine deneme yanılma yöntemi uygulanarak belirlenmiştir. 3-5 mm kuvars kumu için en iyi uyum boyuna dispersivite değeri 12.2 cm, yatay dispersivite değerinin boyuna dispersivite değerine oranı 0.21 ve düşey dispersivitenin boyuna dispersivite değerine oranı 0.05 değerleri ile elde edilirken, bu değerler 1-3 mm kuvars kumu için 5.5 cm, 0.25 ve 0.07æ 0.6-1.2 mm kuvars kumu için de 3 cm, 0.18 ve 0.055 olarak belirlenmiştir. Bu oranlar arazi çalışmaları sonucu elde edilen ve literatürde verilen değerlerle aynı büyüklüktedir. Deney sistemi gerekli ölçüm cihazları sağlanması şartıyla kararlı rejimde olduğu kadar kararsız akım durumunda da kirlilik taşınmasını araştırmak için tasarlanmıştır. Gerekli ölçüm cihazlarının temin edilip bu araştırmaya kararsız akım durumunda da devam edilmesi faydalı olacaktır. In this study, an elaborate experimental system is designed and constructed in Hydraulics Laboratory of the Civil Engineering Department of Dokuz Eylül University, in order to study contaminant transport in homogeneous as well as heterogeneous porous media. A flume 12 m long, 135 cm wide and 60 cm high is built 70 cm over the floor, within Hydraulics Laboratory of Civil Engineering Department of Dokuz Eylül University. The porous media in the channel are constituted by sands of different size, and the tracer tests are carried out by using NaCl as contaminant. The concentrations in various directions are measured and their distributions are determined. Accordingly, the dispersivity values along the flow and in the two directions vertical to flow are determined applying the trial and error method to the relevant theoretical equation, by using Mass Transport 3 Dimensional (MT3DMS) software. The heterogeneous medium is constituted from three horizontal layers with different kind of granular material. The concentration pattern is observed and dispersivity values are determined by trial and error method applied to the advection-dispersion equation. The best match for 3-5 mm quartz sand is obtained for longitudinal dispersivity value of 12.2 cm. The ratios of horizontal transverse dispersivity to longitudinal dispersivity and vertical transverse dispersivity to longitudinal dispersivity are 0.21 and 0.05, respectively. The corresponding values for 1-3 mm quartz sand are 5.5 cm, 0.25 and 0.07 for 1-3 mm quartz sand and for 0.6-1.2 mm quartz sand 3 cm, 0.18 and 0.055. These ratios are in the order of magnitude with those obtained from in-situ tests, given in the related literature. This experimental system is designed to investigate contaminant transport in steady as well as unsteady flow, provided that some required measurement devices are supplied. It will also be beneficial to procure necessary instruments and pursue this study in the case of unsteady flow

Experimental investigation of the effect of vegetation on dam break flood waves

Dams have an important role in the industrial development of countries. Irrespective of the reason for dam break, the flood can cause devastating disasters with loss of life and property especially in densely populated areas. In this study, the effects of the vegetation on the flood wave propagation in case of dam break were investigated experimentally by using the distorted physical model of Urkmez Dam. The horizontal and vertical scales of the distorted physical model are 1/150 and 1/30, respectively. The dam break scenarios were achieved by means of a gate of rectangular and triangular shape. The results obtained from experiments performed with vegetation were compared and interpreted with those obtained from experiments at which the vegetation configuration was absent. The analysis of the experimental data showed that the presence of vegetation causes a significant decrease in water depths as the flood wave propagates to the downstream and greatly reduces its impact on the settlements. It is also revealed that dam break shape plays an important role in temporal variation of flood wave