Flood hazard measurement based on hydrographic unit models in watersheds around Mount Piran

Abstract

Abstract Piran Mountain is the center of seven river basins of the study area. Meanwhile, these basins are different in shape and area, although these watersheds are varied in terms of natural characteristics, which leads to a variety of times of flood and the water flow at the basin output in a specified time. To prove this difference, we used the Unit Hydrography model in this study, which shows that the main condition for flood and the water flow at a specified time in the river’s Watersheds is not only dependent on the catchment area, but more connected to the shape of Watershed, and slope of the drainage network, as in the result of this research presented in Marran Drainage basin from 9 to 12 hours after first rainfall recorded the highest amount of water flow in basin output, and the main reason for this timing is the river basin’s Shape factor. Keywords: River basin, morphometric, hydrographic unit, topography.