Thesis Abstract

Abstract
Flood frequency analysis is a critical component of hydrological studies that helps in understanding the probability and magnitude of floods in a given region. One of the primary inputs required for flood frequency analysis is annual peak rainfall data. This research project aims to compare different methods of flood frequency analysis using annual peak rainfall data collected from various locations. The study utilizes data from multiple rain gauge stations to analyze the flood frequency in the region. Two commonly used methods, the Log-Pearson Type III distribution and the Gumbel distribution, are employed to assess the flood frequency for each location. The analysis includes fitting the probability distributions to the annual peak rainfall data and deriving the associated return periods for different flood magnitudes. In addition to comparing the results obtained from the two distribution methods, this research also evaluates the sensitivity of the flood frequency analysis to the duration of the rainfall data. By considering different durations of annual peak rainfall data, ranging from 10 years to 50 years, the study investigates how the length of the data record influences the flood frequency estimates. Furthermore, the research project explores the impact of climate change on flood frequency analysis using historical rainfall data and projected future climate scenarios. By incorporating climate change projections into the flood frequency analysis, the study aims to provide insights into how changing climatic conditions may alter flood risks in the region. The findings of this research have implications for flood risk management and infrastructure planning in flood-prone areas. By comparing different methods of flood frequency analysis and evaluating the influence of data duration and climate change on flood risk assessments, this study contributes to improving the accuracy and reliability of flood frequency estimates. Overall, this research project highlights the importance of utilizing sound statistical methods and reliable rainfall data for flood frequency analysis. By comparing different approaches and considering various factors that can influence flood frequency estimates, this study enhances our understanding of flood risks and aids in developing effective strategies for flood mitigation and adaptation.

Thesis Overview

 Flood is a basic phenomenon of nature, it occurs during or immediately after an intensive rainfall or large and sudden snow-melt due to increase in temperature (in the glacial/temperate countries). Also, flood is a high water stage in which overflows its natural or artificial banks onto normally dry land such as a river inundated its flood pain. When flood spreads to area of steep slope, it accelerate the runoff, the potential energy immediately takes on an additional and high kinetic energy due to increased velocity. The effects of flood on human well being range from unqualified blessings to catastrophes. The regular seasonal spring flood of the Nile River prior to construction of the Aswan high dam, for example were depends upon to provide moisture for the fertile flood pains of its delta. The uncontrolled flood of the Yantze River and the Huang Ho, have however, repeatedly wrought disaster when these rivers habitually re-chart their courses. Uncontrollable floods likely to cause considerable damage commonly result from excessive rainfall over brief period of time, as, for example the Omiyale flood of the Ogunpa river in Ibadan, Nigeria (1958, 1973 and 1980), the flood of Paris, France (1658 and 1910), of wars haw, England (1861 and1964), potentially disastrous floods may, however, also result from ice jams during the spring rise, as with the Danube, Switzerland (1342, 1402, 1501 and 1830), from storm tides such as those of 1099 and 1953 that the coast of England, Belgium, and the Netherlands; and from tsunamis, the mountainous sea waves cause by earthquakes, as in Lisbon (1755) and Hawaii, U.S.A (Hilo, 1946). Flood can be measured by height, peak discharge, area inundated, and volume of  flow, these factors are important to judicious land use, construction of protective levees and storage reservoirs, and, indirectly, the implementation of programs of soil and forest conservation to retard and absorb runoff from storm and more recently monitoring of river flow by computers using specifically designed software. The discharge volume of an individual storm is often highly variable from month to month and year to year. A particularly striking example of this variability is the flash flood, sudden unexpected torrent of muddy and sporadic rainfall: it is uncommon, of relatively brief duration and generally the result of summer thunderstorms in mountains. A flash flood can take place in a singles tributary while the rest of the drainage basin remains dry. The suddenness of its occurrences causes a flash flood to be extremely dangerous.