C. Ntemiroglou, Optimization of the management of hydroelectric reservoir gates - Application to Arachthos dam, Diploma thesis, 164 pages, Department of Water Resources and Environmental Engineering – National Technical University of Athens, November 2020.
Hydroelectric works are equipped with spillway gates are advantageous, since they ensure an increased hydrodynamic potential, which favors in turn the produced energy. However, in the case of a flood event, careful manipulations are essential, to assure the safety of the dam and the downstream works. These are usually employed on the basis of operation rules that are derived empirically, and not as result of a systematic methology that accounts for the flood regime of the study area as well as the complex process that are taken into place during the flood routing. The objective of this thesis is the development of a novel approach for gate management that combines stochastic simulation and multicriteria optimization, applied to the particularly crucial dam of Pournari I, at Arachthos River. Key component is a numerical scheme for flood routing, which implements a hydraulically consistent method for extracting the flow-stage relationship through ogee-type spillways, and a simulation procedure for the manipulation of gates and turbines, using characteristic level thresholds during the rising and fallinf of a flood hydrograph. By employing the aforementioned methologies at Pournari dam, we determined the aforementioned methologies at Pournari dam, we determined operation rule initially for the design flood of 10000 years return period (local rule), and next for a wide spectrum of smaller floods that have been synthetically generated. Starting from the local rule, we emphasized the investigation of competitiveness between the energy and safety criteria, in order to outcome to a compromise formulation of the optimization problem. Next, from the stochastic analyses we concluded to six operation rules, which refer to flood events of small and large return period, and three initial stage scenarios. In these analyses, we gave further weight to economy (i.e. minimization of energy losses due to spill), in contrast to the local rule, which is conservative as it focuses to the safety of the dam and the downstream works. The most representative rule has been applied to the flood event of year 2005, and its performance proved to be comparative with the successful manipulations by the expertise personnel of PCC.