Summary:
This thesis analyzes the flood history of East Attica whilst drawing up a comprehensive list of historical floods per water catchment area, calculates the frequency of floods and discusses flood risk assessment strategies and the appropriate medium-long term strategies and measures to address this issue in order to reduce it.
The thesis begins by examining the problem of flooding on a global level, noting that flooding is one of the major types of natural disasters, both in terms of economic impact, and in terms of the cost in human lives. Additionally, charts are presented with the annual number of floods, deaths from floods and the annual economic impact on a global scale. Next, the flood problem in the Greek area is addressed, with serious implications such as damage to infrastructure and property as well as loss of life. Then, the thesis focuses on Attica and more specifically on East Attica, the area that is being studied. Regions and water catchment areas with a strong flood problem in the past, which are captured on photographs, are presented. Examples of areas of Attica where disasters and deaths were caused during flooding are also given. At the end of this first chapter, the objectives of the thesis are presented.
In the second chapter, the study area is presented, defined geographically and maps are drawn with the boundaries of the municipalities according to the Kallikratis plan, the relief, the morphological gradients, the hydrographic network, the boundaries of the catchment areas and main settlements of the study area are presented. Following that, the major water catchment areas are presented and the most important characteristics (geographical limits, basin area, stream, settlements etc.) are listed. Then, the numerous sources of data that are retrieved from a number of various sources such as scientific articles, theses, databases and press articles are presented accompanied by a table. This table mentions the type and name of the source, the time coverage as well as a brief description of the data collected. Subsequently, the steps of the methodology used, the basic idea of which is to collect flood event data, the systematization of data and spatial analysis are presented in detail. At the end of this chapter a schematic representation of the procedure followed is shown.
The third chapter presents the results of this thesis. Initially, based on the collection of flood event data from a variety of sources and then from the systematization of data a list (table) with the flood history of the study area, in East Attica is drawn up. This list shows the exact date of the flood event, the location as well as the water catchment area that flooded. According to the analysis of the flood list, 34 floods are marked during the period from 1980 to 2015 in which the recording is considered complete. Then, a table with the number of floods per year in the study area is drawn up. Additionally, the time variation of flood events is studied, a relevant chart is presented and the average flood repetition frequency is calculated (in years) for the period 1980-2015. Moreover, the seasonality of floods allocated to seasons and months of the year are studied and the corresponding diagrams are made. Then, a more extensive analysis of the flood history at catchment level, the study area, by drawing up a list of flood events per water catchment area takes place. This list (table) shows the water catchment area, the flooding date, the number of flood events per catchment area for the period 1980-2015, which is considered a full record and the total number of recorded floods by water catchment area. Also, after studying and processing, the flood frequency and the average flood repetition frequency (in years) per catchment area for the period 1980-2015 is calculated and the corresponding table is created. Additionally, a spatial analysis of data with drawing up maps with the number of floods, the flood frequency, flood recurrence rate and flood risk index for the study area for the period 1980-2015 takes place. Inundation risks are identified (positions, area) throughout the study area by means of the flood risk index map. Then, the most important water catchment areas are examined, by means of studying temporal variability, seasonality of flooding with their distribution according to months of the year and creating the corresponding diagrams. At the end of this chapter, the characteristics of floods for the study area are indicated by recordings and visual material collected.
The fourth chapter studies the current situation of flood protection in the study area and proposals and flood risk reduction measures are discussed. First, the current situation in East Attica is being examined, ascertaining the big problem of flooding phenomena and the absence of adequate flood protection it presents. At the same time, some flood control projects that have been built to date in the region are presented. Subsequently, the current situation in terms of characteristics and flood protection is addressed in water catchment areas of the study area, with the largest flood problem are examined. Flood control projects that have been built in these catchment areas are presented and are reflected in photographs. Furthermore, the areas and locations with the greatest risk of floods are examined and determined by using maps. At the end of this chapter, in order to effectively address the flood risk in the East Attica region, flood risks coping strategies are proposed for each water catchment area according to the problem presented, the characteristics and the current situation in terms of measures. Finally, the conclusions of the thesis are presented.
Keywords:
Floods, FlashFloods, Greece, EastAttica, HistoricalFloods, FloodRisk, FloodHazard, FloodFrequency
