DEFINITION OF FLOOD RISKY AREAS WITH CALCULATION OF STREAM WATER VELOCITY VIA USING NUMERICAL MODEL: CASE STUDY OF FILYOS RIVER, TURKEY

Abstract

The Filyos River is located geographically in the western part of the Black Sea region of Turkey, with a catchment area of about 13,300 km(2). In the region, on the Filyos River, frequently flooding resulting in high costs and loss of life occurs. In this study, the flood risky areas were determined from water velocity and slope of the river using MIKE 11 numerical model. Remote sensing system (RSS) and GIS techniques were used to display slope and velocity properties of the river. The river network plain was divided into 4 streams (Filyos, Arac, Yenice, and Devrek) which has 235 cross sections using over 5,000 data points. The simulation period was established from October 1, 1999 to May 30, 2000. The time step was set to 1 h, and the boundary conditions at downstream discharge area into the sea; defined with constant sea level. Flood events occurred mainly in the river where flow is supercritical (maximum velocity) in steep slope and, then, slope changes to mild slope or the cross section change because of the sediment accumulation. So, the slope, minimum and maximum velocities of the river were calculated to determine the flood risky areas. These results were associated and verified with floods occurred in the region. Results of the numerical model displayed the water velocities, and slope can be adequately used to evaluate the flood risky areas.