- Title
- A screening method for rural flash flooding risk assessment
- Creator
- Senevirathne, Nalin
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2015
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Flash flooding is considered as one of the most disastrous natural hazards, which has had significant impact on human, infrastructure and environment throughout history. By definition, flash flooding occurs within a very short time (usually few hours) of the beginning of rainfall, which results in a limited time frame to issue warnings or prepare for evacuation. Risk assessment can be done using a hydrological model. However, most models require catchment specific data and take considerable execution time. Modelling techniques and the understanding of flash flooding are getting improved with the availability of better quality data such as high resolution Digital Elevation Models (DEM). DEMs allow the automated characterization of the influence of geomorphology on the hydrologic response of catchments. They are particularly useful for small ungauged catchments where available hydrologic data (e.g. rainfall, runoff) are sparse and where site specific studies are rarely done unless some evidence of high risk is available. This research presents new relationships between catchment hydrologic response and instantaneous unit hydrograph (IUH), which led to derive risk indicators that can be used to identify flash flooding risk areas within catchments. New measures are related to the rate of rise of the hydrograph and the catchment response time. Standard terrain analysis methods (pit filling, flow direction, local slope, contributing area, flow velocity and travel time) were used to produce time-area diagram and subsequently IUH, which was calculated for every individual pixel in the catchment. When computing the IUHs, each pixel was considered as the outlet of its own catchment bounded by its contributing area. This allows presenting the hydrological response and risk areas at the finest scale possible for a DEM. To perform this analysis, a fully distributed hydrological model was developed using Python programming language. The model is quite computationally efficient and can be completely automated. The study area includes 37 major river basins covering a 1700km long by 50km wide coastal strip of Eastern Australia. The analysis was done using a high resolution (1 arc second) DEM. Two types of output maps were produced; 1) flash flood risk areas at catchment scale, 2) spatial distribution of hydrologic response within catchments (e.g. high and low responsive areas). Moreover, results were validated using the data of severe flash flooding that occurred around Toowoomba (at the northern end of the coastal strip studied) in January 2011.
- Subject
- flash flooding; instantaneous unit hydrograph; risk assessment; hydrological modelling
- Identifier
- http://hdl.handle.net/1959.13/1313488
- Identifier
- uon:22601
- Rights
- Copyright 2015 Nalin Senevirathne
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
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| View Details Download | SOURCE1 | Abstract | 159 KB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | SOURCE2 | Thesis | 161 MB | Adobe Acrobat PDF | View Details Download |