An improved solution for diffusion waves to overland flow

Diffusion wave equation describes the flood wave propagation which is used in solving overland and open channel flow problems. Therefore, it is important to understand and solve the diffusion wave equations accurately. For this purpose, researchers have previously developed several analytical and numerical methods for the solution of the partial differential equation of diffusion waves. The solution derived by Kazezyilmaz-Alhan and Medina (2007) [12] can be used to solve overland flow problems during rainfall events with both constant and variable rainfall intensity, and with constant hydraulic diffusivity and wave celerity. In this paper, this method is improved by employing the De Hoog algorithm instead of Stehfest algorithm for Laplace inversion and adapting the solution to variable hydraulic diffusivity and wave celerity. In addition, the performances of the Stehfest and the De Hoog algorithms are compared. Synthetic examples are solved by using both Stehfest and De Hoog algorithms incorporated into the existing analytical solution to present the accuracy of the De Hoog algorithm over the Stehfest algorithm. The examples are also solved by using the new method in order to demonstrate the improvement over the existing method. (C) 2011 Elsevier Inc. All rights reserved

Urban Water Atlas for Europe

The Atlas illustrates the role of water in European cities and informs citizens as well as local authorities and experts about good practices and cutting-edge developments that can contribute to ensuring that water is used more efficiently and sustainably, helping to save this valuable resource. Detailed factsheets in the Urban Water Atlas for Europe present the state of water management in more than 40 European cities and regions, together with a number of overseas examples. The atlas also presents cities' 'Urban Water Footprint', a measure of domestic water use as well as water use embodied in agricultural and industrial products consumed. It aims to raise awareness of the large amount of water used to produce food and the striking difference in water needs among different diets. For example, healthier and low-meat diets could save as much as 30% to 40% of water currently used for food production. Apart from providing a wealth of information, the atlas also aims to encourage citizens to take an interest and get involved in water issues by combining the work of scientists, artists, politicians and municipal stakeholders with that of schoolchildren and teachers. The atlas is presented in an innovative, accessible and attractive format. It also attempts to change traditional perceptions of water being a free and infinite resource, and to encourage conservation

Analytical Solutions for Contaminant Transport in Wetlands Incorporating Surface Water and Groundwater Interactions

Wetlands are the transitional zones between uplands and downstream flooded systems; they play an important role in controlling storm water peak flow and downstream water quality. Since surface water/subsurface water interactions affect solute transport within wetlands significantly, contaminant transport models incorporating these interactions need to be investigated for wetland areas. Wetland solute transport dynamics (WETSAND) is a comprehensive wetland model, which has both surface flow and solute transport components. In WETSAND, water quality components are solved by advection-dispersion-reaction equations, which incorporate surface water/groundwater interactions by including the incoming/outgoing mass due to the groundwater recharge/discharge. In this study, analytical solutions for the contaminant transport equations of WETSAND are developed and compared to the numerical solutions obtained by WETSAND. These analytical solutions provide a physical insight to wetland water quality. Results show that analytical solutions are in good agreement with the numerical solutions. Moreover, the effect of interactions on wetland water quality is discussed. (C) 2014 American Society of Civil Engineers

Analytical solutions for contaminant transport in streams

The importance of the effect of surface/ground water interactions on contaminant transport in streams and rivers has been greatly recognized in the last two decades. Bencala and Walters (1983) [Bencala, K.E., Walters, R.A., 1983. Simulation of solute transport in a mountain pool-and-riffle stream - a transient storage model. Water Resources Research 19 (3), 718-724.] developed a mathematical model for the transient storage zone to represent the movement of solute from main streams into stagnant zones and back to the main stream. This model calculates the concentrations of a main channel and a storage zone and the transient storage is represented by the mass exchange due to the concentration difference between the stream and the storage zone. Later, Kazezyllmaz-Alhan and Medina (2006) [Kazezyitmaz-Alhan, C.M., Medina Jr., M.A., 2006. Stream solute transport incorporating hyporheic zone processes. Journal of Hydrology 329 (1-2), 26-38.] made several improvements to this transient storage model by incorporating advection and dispersion into the hyporheic zone and representing the mass transport between the channel and hyporheic zone by mass flux terms. In this study, analytical solutions are derived for both transient storage models for the cases of continuous and finite injections of a tracer. The analytical. solutions provide the researchers with computational speed in obtaining results for contaminant transport problems, and a means to check the validity of the numerical models. The analytical solutions are compared to the numerical solutions for hypothetical problems. Comparison of results shows that the numerical and analytical solutions are in very good agreement. (c) 2007 Elsevier B.V. All rights reserved

MAVİ ŞEHİRLER: Su ve Atık ile Avrupa Akıllı Şehir Stratejisinin Entegrasyonu: Mavi ve Sarı Ayak İzi Kavramlarının İstanbul için Uygulaması

Çevresel sürdürülebilirliği arttırmayı amaçlayan “Akıllı Şehir” yaklaşımı son yıllarda özellikle gelişmiş ülkelerde önem kazanmaktadır. Bu kapsamda, su kaynaklarının korunarak çevresel sürdürülebilirliğin sağlanması için “Akıllı Şehir” yaklaşımı faydalı olmaktadır. Bu anlamda, Akıllı Şehirler su, atık, altyapı, sağlık, güvenlik, çevre, enerji ve ulaşım gibi alanlarda gelişmiş bir kent bilgi sistemine sahip şehirler olarak tanımlanabilir. Bu çalışmada, İstanbul Üniversitesi’nin paydaş olarak yer aldığı Avrupa Birliği Ufuk 2020 Programı kapsamında desteklenen projenin İstanbul saha çalışması yer almaktadır. “Akıllı Şehirler için Mavi Ayak İzi: EIP Akıllı Şehirler ve Topluluklar çerçevesinde Su ve Atık Sektörlerinin Entegrasyonu için bir Yöntem (Mavi Şehirler)” adlı proje kapsamında şehirler için Mavi Ayak İzi ve Sarı Ayak İzi kavramları oluşturulmuştur. Daha sonra 4 pilot şehir seçilerek her şehir için Mavi Ayak İzi ve Sarı Ayak İzi puanları hesaplanmıştır. Ayrıca her şehirde uygulanan çözümler incelenmiştir. Bu sayede iyi durumda olan yani ayak izi değerleri yüksek olan şehirlerdeki uygulamalar diğer şehirler için örnek teşkil etmiştir. Bu çalışmada Mavi Ayak İzi ve Sarı Ayak İzi kavramları anlatılmış ve projede yer alan İstanbul şehri için elde edilen sonuçlar sunulmuştur