Flood Hazard Zonation using the Fema Instructions Case Kurdan Alluvial Fan

Abstract

Alluvial fans are among the most prominent landscape features throughout the semi-arid and arid regions of the world. The importance of developing qualitative and quantitative understandings of hydraulic processes on these features primarily comes from the rapid and significant development that has taken place on them in the American Southwest over the past four decades, development that is continuing and whose pace may be accelerating. As development and unplanned urban sprawl moved from valley floors onto alluvial fans, the amount and seriousness of damage incurred from infrequent flow events has dramatically increased. Whether the development on alluvial fans is planned or unplanned, seems to make little difference because we have an inadequate understanding of both the size of the flood events that might be expected and how they will behave when they occur. This study has tried to use the guidelines suggested by FEMA (1989) for flood zonation hazard of Kordan Alluvial Fan. While specifying the limits of the Kordan Alluvial fan and stream, in its active and inactive areas, the width and depth of one hundred-year flood is calculated using the Fan Program software and delineated maps of flood zones. This zonation showed that the most dangerous regional flood zoning is located at the head of the alluvial fan area with residential landuse (Kordan Village), therefore, protection of this area is highlighted.