American Journal of Engineering, Technology and Society 2015; 2(4): 77-84 Published online June 10, 2015 (http://www.openscienceonline.com/journal/ajets) Determining the Hydraulic Geometry Parameters of Seyhan River M. Ishak Yuce 1 , Musa Esit 1, 2 , Abdullah Muratoglu 3 1 Civil Engineering Department, University of Gaziantep, Gaziantep, Turkey 2 Civil Engineering Department, University of Adıyaman, Adıyaman, Turkey 3 Civil Engineering Department, University of Batman, Batman, Turkey Email address yuce@gantep.edu.tr (M. I. Yuce), mesit@adiyaman.edu.tr (M. Esit), abdullah.muratoglu@batman.edu.tr (A. Muratoglu) To cite this article M. Ishak Yuce, Musa Esit, Abdullah Muratoglu. Determining the Hydraulic Geometry Parameters of Seyhan River. American Journal of Engineering, Technology and Society. Vol. 2, No. 4, 2015, pp. 77-84. Abstract Cross-section of rivers vary by time due to the dynamic structure of hydraulic geometry. The hydraulic geometry parameters of rivers including the width, depth and velocity are related to its discharge as simple power functions at a given cross-section. The characteristics of a river can be determined by using the hydraulic geometry parameters. The aim of this study is to determine the downstream and at-a-station hydraulic geometry parameters of Seyhan River. The hydraulic geometry parameters are estimated by employing the daily discharge values and the cross-sectional data of seven flow measurement stations located on the main river and its tributaries. The results of the analyses show that both the summation of the exponents and the multiplication of the coefficients are almost unity. These outcomes are expected to be helpful in developing water resources projects the basin. Keywords River Geometry, Downstream Hydraulic Geometry, At-a-Station Hydraulic Geometry, Seyhan River, Power Functions 1. Introduction The quantitatively measured hydraulic characteristics of a river, such as the water surface width, the average water depth and the flow velocity, change with its discharge as a simple power function, at a cross-section. The relationship established between the hydraulic characteristics and the discharge of a river is expressed as the hydraulic geometry. This relation is either for (i) downstream or (ii) at-a-station hydraulic geometry (Leopold and Maddock, 1953; Rhoads, 1991; Singh, 2003). Both the downstream and at-a-station hydraulic geometries of the Seyhan River are examined in this study. Determining the hydraulic geometry of a river is essential in canal designing, irrigation works and hydropower production. A number of theories have been suggested to assess the hydraulic geometry of rivers. Some of these theories are related to each other, while some others are based on slightly different principles (Singh, 2003). Almost all of the theories assume that the river flow is uniform and steady. The most effective estimation of the hydraulic geometry was provided by Leopold and Maddock (1953) as in equation 1. B=aQ b H=cQ f V=kQ m (1) where, Q is the discharge of the stream, B is the water surface width, H is the average water depth, V is the average stream flow velocity, a, b, c, f, k and m are numerical constants. The hydraulic geometry parameters, specifically, the water surface width, the average water depth and the average stream flow velocity must satisfy the continuity equation. Therefore, the summation of the exponents and the multiplication of the coefficients must give a mathematical value of unity. Various studies have been conducted and multiple efforts have been made to understand the characteristics of different rivers. Park (1977) has analyzed 139 at-a-station sites and 72 downstream cases. Rhoads (1991) has investigated the hydraulic geometry variations and stated that generally the exponents are less variable than the coefficients. Huang and Nanson (1997) noted that the hydraulic geometry exponents vary significantly from one stream to another. Howard (1980) indicated that the values of hydraulic geometry parameters vary continuously depending on the bed material of alluvial