A. Burcu Altan-Sakarya

Assessment of sediment yield estimations for large watershed areas: a case study for the Seyhan, Demirköprü and Hirfanlı reservoirs in Turkey

Abstract Analyses of data from reservoir surveys and sediment rating curves are compared to predict sediment yield in three large reservoir watershed areas in Turkey. Sediment yield data were derived from reservoir sedimentation rates and suspended sediment measurements at gauging stations. The survey data were analysed to provide the volume estimates of sediment, the time-averaged sediment deposition rates, the long-term average annual loss rates in the reservoir storage capacity, and the long-term sediment yield of the corresponding watershed areas. Four regression methods, including linear and nonlinear cases, were applied to rating curves obtained from gauging stations. Application of the efficiency test to a power function form of a rating curve with nonlinear regression yielded the highest efficiency values. Based on the analysis of the sediment rating curves, sediment load fluxes were calculated by using average daily discharge data at each gauging station. Comparison of these two sediment yield values for each reservoir showed that the sediment yields from the suspended sediment measurements, SYGS, are 0.99 to 3.54 times less than those obtained from the reservoir surveys, SYRS. The results from the reservoir surveys indicate that all three reservoirs investigated have lost significant storage capacity due to high sedimentation rates.

Optimal scheduling of booster disinfection in water distribution networks

ABSTRACT Booster disinfection stations are the solution alternative to maintain required disinfectant residual concentration in water distribution networks. In the present study, an optimisation problem to determine the optimum injection rates is solved. The minimisation of the total injected mass is considered as the objective function which is subjected to bound constraints on chlorine concentration. Two formulations are used for the linear optimisation problem, with and without considering the initial concentrations as unknowns. Determination of variable network hydraulics and chlorine concentrations is achieved by EPANET. A C++ code was developed to interface with EPANET by means of the EPANET Programmers Toolkit for optimisation of the disinfectant mass applied to the network. Finally, a cross check is achieved in EPANET software for both disinfectant residual concentrations and linear superposition principle.

Optimum design of slurry pipelines by genetic algorithm

Various applications of slurry transportation through pipelines exist. A transportation problem is formulated to determine the pipe diameters and amounts of transported slurry from the production to the consumption points. The minimisation of the cost consisting of the pipe and energy cost terms is considered as the objective function. Pipe cost is given as the function of pipe diameters and the energy cost is defined as the function of pipe diameters and slurry amounts. Energy cost is obtained by using the relation that is previously determined after the experimental studies have been made for the magnetite ore. Genetic algorithm is used as the optimisation method and to apply this method a commercially available software written in the C language is used and modified. The proposed methodology to solve this non-linear programming problem is applied to a transportation system and it is found that the proposed methodology has made the complex, labour-intensive solution process very convenient for the users.

Application of a flow-measurement structure for sediment-laden streams

Generally, measurement of flow in natural streams is accomplished by measuring the flow depth. Hence, the relationship between the water level and discharge should be obtained in advance. However, in streams with high sediment load, the bottom level may change due to sediment deposition, preventing the single relation between water level and discharge. This paper summarizes the application of a flow-measurement structure for sediment-laden streams. The proposed structure is designed and built in Turkey and has been under operation since 1998 without any sedimentation problem. The agreement between the real data obtained from the structure and the theoretical rating curve is quite reasonable.