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The purpose of this study is to explain the formation mechanism of the floods which occurred in the Keçidere basin in 2009. In this study, discharge data in between 1981 and 2009, digital elevation model (DEM), satellite images and field works were used as a main data sources. LPT3 was applied to 29-year maximum flow data to produce different flood return periods such as 2, 5, 50, 100, 200, 500 and 1000-year flood. The DEM was created using 1:25,000 topographic contours with Topo to Raster interpolation techniques in geographical information systems (GIS). Land use and some geometric data were digitized using high resolution satellite images for hydraulic modelling purposes. Simulation of the 2009 flash flood event and different return periods flow data was done using one-dimensional hydraulic modelling with HEC-RAS. In the last phase, results obtained from the simulations and field works were compared based on fits statistics and mean absolute error in terms of extent and depth. An analysis of water extent and depth features observed during the highest flow ever measured in the basin revealed that the result overlapped with 500-year inundation extent. Overall, the results of the research indicate that GIS is an effective environment for floodplain mapping and analysis. 相似文献
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Natural Hazards - Extreme maximum (Tx) and extreme minimum temperature (Tn) frequency distributions during summer and winter for blocked conditions were analyzed within Turkey during the period... 相似文献
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S. I. Efe 《Natural Hazards》2010,55(2):307-319
The study adopted the experimental research design and field survey of the oil-producing region of Nigeria for the past 10 years.
A total of 100 sterilized rain gauges were randomly distributed on the basis of 50 each to the eastern and western division
of the oil company operating in the region. The rainwater samples harvested through this process were transferred into sterilized
plastic containers and kept in coolers and taken immediately to the laboratory for analysis soon after every rain event. The
rainwater samples were analysed in the laboratory with the most appropriate techniques. The physicochemical characteristics
of rainwater harvested were subjected to paired t test and 3-year moving average statistical analysis. The following are the results: There is widespread acid rain in the
region, this is evident from pH values that span 4.98–5.15 and 5.06 mean values. The result also revealed that acid rain (pH)
varied significantly (P > 0.05), and it decreases with increasing distance from gas flare sites throughout the period of study. Other physicochemical
characteristics of rainwater resources conform to safe limit with the exception of turbidity, TSS, Pb and NO3, which is also significant at P > 0.05 with increasing distance from the gas flare sites, as such they decreases with increasing distance. This certainly
has serious environmental effects on the human and other species, soil, water and vegetation resources and calls for the extinction
of gas flaring, in this region. Sources of water that are acidified should be periodically limed to reduce the acid concentration
in such water. 相似文献
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