Extreme rainfalls as a cause of urban flash floods; a case study of the Erbil-Kurdistan Region of Iraq

Abstract

Aim of the study: The current paper aims to give a detailed evaluation and analysis of some extreme rainfall events that happened in the last decade in terms of spatial and temporal rainfall distribution, intensity rate and exceedance probability. Moreover, it examines the effects of each analysed aspect on the resulting flash floods in the study area. Material and methods: American Meteorology Society (AMS) in their glossary of meteorology divided rainfall intensity types into four groups (light, moderate, heavy, and violent). Also, for estimating the exceedance probability, Lognormal distribution was applied as a statistical model of the precipitation probability distribution function. Results and conclusions: Out of six episodes, five of the analysed events were classified as heavy rainfalls. However, the duration of heavy rainfalls was not more than two hours. Four events of maximum daily rainfall (for a 39-year dataset) were rated from 1 – 10% of exceedance probability. To conclude, the current study can be an initial step in modelling hydrological events in the study area and in the process of transforming precipitation into the outflows of urban basins in the future.

Keywords

• climate change
• rainfall intensity
• urban flash floods
• rainfall probability distribution
• rainfall temporal distribution