پهنه بندي خطر و ارزيابي خسارت سيل با استفاده از hec-georas: مطالعه موردي رودخانه بابلرود

Flood Hazard Zoning and Damage Assessment Using HEC-GeoRAS (Case Study: Babolrood River)

In this research, the HEC-RAS model and its extension HEC-GeoRAS and their applications and capacities, as well as combination with the Arc View software, and introduced and flood zoning concerning the flood plain of Babolrood River was studied and damage to the plain as the result of floods was assessed. For this purpose, maps with 1:1000 scales were prepared and the study began in 103 sections within 5.5 km along the river. Hydrological data were collected and based on the Cawen method the roughness coefficient was determined in ten areas with approximate 500 meter distances between the points. Employing certain methods and operations, maps of the area, depth and velocity of floods in seven flood occurrences in 2, 5, 25, 50, 100 and 200 years ago were prepared, and damage to adjacent rice fields was assessed and related damage curves were drawn. The results had shown that about 89.53% of the flood area over past 200 years is prone to flooding according to the patterns in last 25 years. The damage curve shows that the rate of damage increases with the increase in the flooding depth up to the medium depth (2.82 m) while the damage rate decreases in medium depths more than 2.28 m. among Babolrood section 1, Babolrood section 2 and Sajjadrood, the highest depth of flooding is found in the Babolrood and the velocity of flooding in sections 1 and 2 of Babolrood is higher than the velocity in the Sajjadrood section.