Rainfall Event Analysis for Urban Flooding Study Using Radar Rainfall Data.

Abstract

Urban flooding is one of the most serious challenges facing urban areas and causesdestruction of properties and major problems for people living in urban areas. Itoccurs in an urban area when intense convective rainfall happens that is higher thanthe capacity of the urban drainage system. Rainfall data can be recorded by radar andby rain gauge. It is essential for urban flooding studies to have access to high qualityrainfall data in attempting to reduce and tackle this challenge. The main aim of thispaper is to test the quality of radar data by means of rainfall event analysis. Radardata obtained from Yorkshire Water were analysed and compared to rain gauge dataduring selected rainfall events in a study area located in North Yorkshire in the UK.Rainfall intensity curves within 5 minute and one-hour intervals, cumulative rainfalldepth curves and normalised bias were used as standard methods for comparisonbetween radar and rain gauge data during the selected rainfall events. Available datawere collected for June, July, and October 2008 and were recorded from Blackhill,Harrogate North, and Helmsley rain gauges, and radar data for these same locationswere also collected. The results of this thesis show that certain errors might have animpact on radar data in terms of quality. Some such errors caused overestimation ofradar rainfall data, such as anomalous propagation error and error related tothunderstorm. However, other errors, such as attenuation, caused underestimation inradar rainfall data.