Flooding is recognized as one of the natural disasters that cause significant damage to human societies and the environment annually. Various definitions of flooding have been proposed. A flood refers to a flow with a height and level above the usual limit that leads to the inundation of low-lying surrounding areas. Additionally, a flood is defined as a high discharge flow that causes damage in flood-prone areas. In this research, the HEC-FIA model from the US Army Corps of Engineers was used to estimate flood damage. To assess flood damage, the following steps were taken: identifying damage-causing periods and preparing flood inundation maps in the HEC-RAS environment, simulating cross-sections using ground elevation model maps and hydrological data, and assigning roughness coefficients to cross-sections and simulating steady and unsteady flows. After post-processing, the flood maps were converted into a format readable by the HEC-FIA software. Also, the land use map of the area was updated using satellite images and field visits. Results indicated that most of the area’s land uses were agricultural and orchard, with residential uses being isolated and scattered. Additionally, fish farming ponds were observed along the riverbanks. Consequently, with the use of the HEC-FIA software, flood damage estimation in various areas can be carried out. Flood maps, along with economic, agricultural, and demographic information, were input into the software to eva‎luate the damages to residential, industrial, and agricultural sectors. Results showed that the flood in the Samirum watershed on March 11, 2006, inflicted serious damage to agricultural and structural sectors. The total damage to the agricultural sector was 821,098,959,070 Rials, of which 11,838,851,680 Rials pertained to apple orchards, and 809,260,107,390 Rials related to rice farming. In the structural sector, damages amounted to 3,026,000,820 Rials. Damage assessment was also conducted for different return periods: the 1,000-year return period caused 1,427,226,553,800 Rials damage to agriculture and 44,946,366,260 Rials to structures; the 500-year return period caused 1,208,030,754,000 Rials damage to agriculture and 33,273,453,000 Rials to structures; the 200-year return period caused 1,009,009,761,000 Rials damage to agriculture and 20,198,450,840 Rials to structures; the 100-year return period caused 908,507,238,000 Rials damage to agriculture and 12,053,779,200 Rials to structures; the 50-year return period caused 895,343,983,000 Rials damage to agriculture and 3,076,224,900 Rials to structures; and the 25-year return period caused 774,692,636,000 Rials damage to agriculture and 1,142,597,820 Rials to structures. The 10-year, 5-year, and 2-year return period floods caused no damage to structures but resulted in agricultural damages of 632,462,954,000 Rials, 598,900,842,000 Rials, and 477,146,849,000 Rials, respectively

رضا مدرس , سعيد سلطاني كوپائي

سعيد اسلاميان , سعيد پورمنافي