DBPapers
DOI: 10.5593/SGEM2016/B31/S12.085

SENSITIVITY STUDY FOR THE MINOR RIVER BED CALCULATION FOR SMALL HYDROPOWER PLANT CAPRA VII

V.F.Pоraianu, C. Dragoi, C. Ilinca, C.Anghel
Wednesday 7 September 2016 by Libadmin2016

References: 16th International Multidisciplinary Scientific GeoConference SGEM 2016, www.sgem.org, SGEM2016 Conference Proceedings, ISBN 978-619-7105-61-2 / ISSN 1314-2704, June 28 - July 6, 2016, Book3 Vol. 1, 653-660 pp

ABSTRACT
Small hydropower plant (SHPP) represents one of the most used form of renewable energy generation. Modern countries are already using an important percentage of their potential in (small) hydropower (e.g. Austria, Switzerland, Germany, etc.). In Romania, small hydropower plants are considered hydroelectric power plants with installed capacity of maximum 10 MW.
One of the important challenges that this domain is facing is the diminishing of the negative impact on the environment. This impact is generated by the location of the project itself (mountain areas, protected areas), the project specificity according to the natural layout (considerable lengths of penstocks, number of water intakes, power house position, etc.) and due to construction periods (difficult access, works in the river bed). Environmental restriction establishes ground rules for the servitude flow (ecological flow) and for the limitation in impact of the hydropower structures to the minor river bed (e.g. water intakes surfaces and penstocks surfaces occupied in the minor river bed). The estimation of the minor river bed is a challenging task especially when the shape of the river bed is affected by forest exploitation or is based on rock solid mountain structures, like the case of SHPP Capra VII on River Capra in Romania.
This paper presents an analysis regarding the sensitivity study for the determination of the minor river bed in order to comply with the existing norms and regulation issued by Romanian water and environmental authorities. Modelling and simulation was used to obtain knowledge for the fundamentals of design.
In order to make a complete analysis, a topographic measurement was completed for the entire river sector of SHPP Capra VII and a complete hydrological study was obtained. Based on this data, a digital model of the river was developed in HEC-RAS software. A series of water speed measurement were done in different points of each section of the river from the topographic measurement in order to determine the flow and to calibrate the digital model with appropriate Manning roughness coefficient. A validation and calibration of the model was afterwards completed. Based on the hydrological study and the values of specific flows according to the definition of minor river bed, the flow with 80% distribution from the daily average flow duration curve, was used to compute the exact width of the river in every river section in order to compute the surface of the water covering the minor river bed. The results of this research, were used in the design of the main structures of the SHPP in order to minimize the use of minor river bed with the main objective to diminish the negative impact on the environment.

Keywords: small hydroelectric power plant, minor river bed, river simulation