Chance-constrained linear programming method in determining the reservoir storage capacity and operation policy [Rezervuar hacmi ve işletme politikasinin belirlenmesinde şans kisitli dogrusal programlama yönteminin kullanilmasi]

Chance-Constrained Linear Programming method with the Linear Decision Rule (LDR) has been used for estimating the capacity and operation policy of a reservoir since 1969. Two version of the methods and their algorithm for direct solutions have been given in the references. In this study, a computer program was developed for the method. The program can solve the problem by both the direct and simplex methods. This computer model was applied to several reservoirs in the Seyhan Basin and the results obtained were compared to other widely used methods' solutions

Experimental investigation of boundary shear stress in smooth rectangular channels

ln this study, the results of some experiments are reported concerning the boundary shear stress, boundary shear force and the aspect ratio. Some empirically derived equations are presented giving the percentage of the total shear force carried by the walls as a function of the breadth/depth ratio. These new empirically derived equations are compared with the equations based on experimental data given by Knight et al

Contraction and expansion losses through bridge constrictions

The U.S. Federal Highway Administration (FHA) method for computing bridge backwater was modified on the basis of significantly large prototype data (Neely 1966; Bradley 1978). Both the water surface profile and the backwater amount given by the original FHA method, which was developed after extensive laboratory model studies, differed appreciably from those recorded on natural reaches around highway bridges. Although a satisfactory explanation for this discrepancy was not given, most of the design charts of the FHA method were modified according to the prototype data (Bradley 1978). Here, a clear-cut explanation is given, and a modification for the bridge subroutine of the commonly used package program HEC-2 is suggested

Multi-stage flood routing for gated reservoirs and conjunctive optimization of hydroelectricity income with flood losses

A six-stage operation policy for routing of flood hydrographs of return periods from 1.01 year up to the Probable Maximum Flood (PMF) for any dam having a gated spillway is proposed. The gate opening rules are determined depending on the recent pool level. Regardless of the size and timing of any incoming floods, the fixed rules of the six-stage operation policy will provide optimum routing for all, which are classified into six different groups based on their return periods. 10-, 100-, 1000-, 10 000- 100 000-year floods, and PMF are the upper limits for the six groups. Next, an Incremental Dynamic Programming programme is developed to optimize both the firm and secondary energies of hydroelectric generation at monthly periods. First, the six-stage flood routing programme is applied sequentially to three dams, all on the Seyhan River in Turkey, for 18 combinations resulting from different active storages, and optimum flood operation policies for all three dams for all 18 combinations are determined. Second, the Dynamic Programming programme is applied to these three dams, and optimum hydroelectricity generation policies for all 18 combinations are computed. Finally, the optimum active and flood retention storages for the three dams are determined so as to maximize the net probability-weighted present worth of hydroelectricity benefits minus flood damage costs

Flood frequency analysis of Turkey using L-moments method

The index flood procedure coupled with the L-moments method is applied to the annual flood peaks data taken at all stream-gauging stations in Turkey having at least 15-year-long records. First, screening of the data is done based on the discordancy measure (D i) in terms of the L-moments. Homogeneity of the total geographical area of Turkey is tested using the L-moments based heterogeneity measure, H, computed on 500 simulations generated using the four parameter Kappa distribution. The L-moments analysis of the recorded annual flood peaks data at 543 gauged sites indicates that Turkey as a whole is hydrologically heterogeneous, and 45 of 543 gauged sites are discordant which are discarded from further analyses. The catchment areas of these 543 sites vary from 9·9 to 75121 km 2 and their mean annual peak floods vary from 1·72 to 3739·5 m 3 s -1. The probability distributions used in the analyses, whose parameters are computed by the L-moments method are the general extreme values (GEV), generalized logistic (GLO), generalized normal (GNO), Pearson type III (PE3), generalized Pareto (GPA), and five-parameter Wakeby (WAK). Based on the L-moment ratio diagrams and the |Z dist|-statistic criteria, the GEV distribution is identified as the robust distribution for the study area (498 gauged sites). Hence, for estimation of flood magnitudes of various return periods in Turkey, a regional flood frequency relationship is developed using the GEV distribution. Next, the quantiles computed at all of 543 gauged sites by the GEV and the Wakeby distributions are compared with the observed values of the same probability based on two criteria, mean absolute relative error and determination coefficient. Results of these comparisons indicate that both distributions of GEV and Wakeby, whose parameters are computed by the L-moments method, are adequate in predicting quantile estimates. © 2011 John Wiley & Sons, Ltd

Hydropower optimization for the lower seyhan system in Turkey using dynamic programming

Dynamic programming with successive approximation has been used in the past for optimizing multi-reservoir water resources systems. In this study, the State Incremental Dynamic Programming (SIDP) model is developed for energy optimization of multi-reservoir systems. A random file access method is used for reaching initial and intermediate data to cope with the curse of dimensionality of dynamic programming. A conventional dynamic programming method is used for each single reservoir to find the initial trajectory of the reservoirs. Then, the computer program developed in the study is applied to the multipurpose-multi-reservoir system in Lower Seyhan Basin, which has six reservoirs, some of which are serial and some parallel. First, extended historical flows were used to maximize firm energy in the critical period, and then total energy in the total flows. The program was run with 50-year long segments (20 flow scenarios) of the synthetic flow data generated by using the HEC-4 generalized computer program to take into account the stochastic nature of stream flows. An increment of approximately 20 percent in total energy was obtained by using the model for the Lower Seyhan System, as compared to that calculated previously by conventional methods.. © 2005 International Water Resources Association

Shear stress distributions along the cross section in smooth and rough open channel flows

Distributions of shear stresses throughout the entire cross-section within the fully developed boundary layer region in both the smooth and rough surfaces of a rectangular open channel flow were experimentally determined. Velocity measurements were taken for two different surfaces and 48 flow conditions with Froude numbers in the range: 0.12 ? Fr ? 1.23 and with aspect ratios within: 4.2 ? b/h ? 21.6. For all the flow conditions created in the setup, the local shear stress was computed using the universal logarithmic distribution. The relationships between the mean cross sectional shear stresses and the aspect ratio, and Froude numbers were determined for both smooth and rough surfaces. For all the flow conditions formed in the setup, the shear stress distribution along the cross section was succinctly expressed by a second degree polynomial. The maximum shear stress on the bed was found to be about 6-20% greater than the mean bed shear stress for smooth surfaces and 2-16% grater for rough surfaces, respectively

Conjunctive optimization of hydroelectricity benefits and flood damage costs

An Incremental Dynamic Programming program is developed to optimize both the firm and secondary energies of hydroelectric generation at monthly periods. First, the six-stage flood routing program developed in a previous study is applied sequentially to the Yedigoze, Catalan, and Seyhan dams, all on the Seyhan River in Turkey, for 18 combinations resulting from different active storages, and optimum flood operation policies for all three dams are determined. Second, the Dynamic Programming program is applied to these three dams with 18 combinations, and optimum hydroelectricity generation policies for all three dams are computed. Finally, the optimum active and flood retention storages for the three dams are determined so as to maximize the net difference of the probability-weighted present worths of (hydroelectricity benefits) - (flood damage costs)

Hydropower Optimization for the Lower Seyhan Basin System in Turkey using dynamic programming

Dynamic programming with successive approximation has been used in the past for optimizing multi-reservoir water resources systems. In this study, a State Incremental Dynamic Programming (SIDP) model is developed for energy optimization of multi-reservoir systems. A random file access method is used to generate initial and intermediate data and cope with the curse of dimensionality of dynamic programming. The conventional dynamic programming method is used for each single reservoir to find the initial trajectory of the reservoirs. Then, the computer program developed in the study is applied to the multipurpose-multi-reservoir system in lower Seyhan basin, which comprises six reservoirs, some serial and some parallel. Extended historical flows are used to first maximize firm energy in the critical period, and then total energy over the entire period of flow records. The program is run with 50-year long segments (20 flow scenarios) of the synthetic flow data generated by using the hec-4 generalized computer program to account for the stochastic nature of streamflows. A 20% approximate increase in total energy is obtained by using the developed model for the lower seyhan basin system as compared to that calculated previously by conventional methods. © 2006 International Water Resources Association