DBPapers
DOI: 10.5593/sgem2017H/33/S12.054

UTILIZATION OF AN EXISTING MULTIPURPOSE SMALL WATER RESERVOIR IN REDUCING FLOOD FLOWS

R. Vyleta, P. Valent, M. Danacova
Thursday 23 November 2017 by Libadmin2017

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgemviennagreen.org, SGEM2017 Vienna GREEN Conference Proceedings, ISBN 978-619-7408-27-0 / ISSN 1314-2704, 27 - 29 November, 2017, Vol. 17, Issue 33, 431-438 pp; DOI: 10.5593/sgem2017H/33/S12.054

ABSTRACT

An increasing frequency and magnitude of flash floods motivates water managers and other authorities to focus on enhancing flood protection of small headwater watersheds, which are especially vulnerable to this type of flooding. One of the ways how to achieve this goal is to increase the volume of existing small water reservoirs (SWR) dedicated to store flood wave. This paper investigates the possibilities of utilizing a SWR Vrbovce (west of Slovakia), which is currently being used for water supply and fishery, in reducing flood discharges. Within the work a flood wave of a return period of 100 years was estimated using a design storm approach. The following assumptions were made: the design storm event generated a flood wave of the same return period; the design storm had a constant intensity and its duration was equal to the time of concentration; the shape of the flood wave hydrograph was triangular with a rising:falling limb ratio of 1:2. In order to transform the flood wave through the SWR a simple model was proposed taking into account hydraulics of the SWR’s outlet objects. The flood wave transformation was carried out for the current state of the reservoir’s operation as well as for three alternative scenarios with smaller values of the initial water volume. In addition a relationship was built between the water level and the transformation effect of the SWR. The results showed that even a small decrease of the initial water level could significantly increase the ability of the SWR to flatten the 100-year flood wave.

Keywords: small water reservoir, IDF curve, design flood, flood wave transformation, SCS CN method