Obtaining of the unit hydrograph by selecting appropriate flood prediction method for designing Filyos river levees

Abstract

Purpose Due to the fact that there are airports, settlements and agricultural areas close to the Filyos flood basin, it is the construction of Filyos levees by obtaining the unit hydrograph by selecting the appropriate flood prediction method. Design / Methodology / Approach Floods are one of the most complex and important problems of engineering hydrology. This is a common problem in many countries, including Turkey. Floods create a risk for urban areas, infrastructure, industrial structures and agriculture. Levees are built along the riverbanks including in Turkey to mitigate the effects of flooding due to the overflowing of rivers all over the world and Filyos levees are one of them. The fact that it is close to the airport, residential areas and agricultural areas to the flood area has been important for the construction of the Filyos levees. Precipitation is very high in the flood area downstream of this basin. Several hydrological studies are carried out to identify floods. The hydrograph shows the change in flow rate over time in a stream section. Unit hydrograph is the hydrograph of the direct flow of residual precipitation at a unit height (1 cm) of constant intensity falling into the basin for a certain period of time. Statistical, Rational, Mockus and Synder methods are widely used for flood prediction. Each method has some important limited conditions and these methods give different results for the same site. The maximum flood flow rate was calculated for the maximum flood where any building can remain safe. Deterministic and statistical methods are used for flood flow. In this study, the unit hydrograph method (deterministic) is used. Since the basin area is larger than 1000 km2 , Snyder method can use.Findings Snyder method was selected according to the meteorological, hydrological and topographic conditions of the Filyos Basin and a unit hydrograph was formed. In the calculation of flood peaks of the Filyos river exit basin, which should be repeated 100 years using synthetic methods; precipitation hydrograph peak flows were found to be 2120 (m3 /sec) and peak flow was approximately 31 hours. It was resumed approximately 144 hours after the peak flow.Originality/value Flood (peak) flow and unit hydrograph graphic created according to Snyder method can be taken as basis in the design of flood protection structures to be created in possible floods in the basin. In addition, a good risk and economic analysis should be carried out as floods will cause loss of life and property. Regular and continuous measurements should continue, as the risk of flooding is high due to the rainy season in this basin.