Flash flood hazard mapping is a supporting component of non-structural measures for flash flood prevention. Pilot case studies are necessary to develop more practicable methods for the technical support systems of fla...Flash flood hazard mapping is a supporting component of non-structural measures for flash flood prevention. Pilot case studies are necessary to develop more practicable methods for the technical support systems of flash flood hazard mapping. In this study, the headwater catchment of the Xiapu River Basin in central China was selected as a pilot study area for flash flood hazard mapping. A conceptual distributed hydrological model was developed for flood calculation based on the framework of the Xinanjiang model, which is widely used in humid and semi-humid regions in China. The developed model employs the geomorphological unit hydrograph method, which is extremely valuable when simulating the overland flow process in ungauged catchments, as compared with the original Xinanjiang model. The model was tested in the pilot study area, and the results agree with the measured data on the whole. After calibration and validation, the model is shown to be a useful tool for flash flood calculation. A practicable method for flash flood hazard mapping using the calculated peak discharge and digital elevation model data was presented, and three levels of flood hazards were classified. The resulting flash flood hazard maps indicate that the method successfully predicts the spatial distribution of flash flood hazards, and it can meet the current requirements in China.展开更多
Southern Red Sea flooding is common. Assessing flood-prone development risks helps decrease life and property threats. It tries to improve flood awareness and advocate property owner steps to lessen risk. DEMs and top...Southern Red Sea flooding is common. Assessing flood-prone development risks helps decrease life and property threats. It tries to improve flood awareness and advocate property owner steps to lessen risk. DEMs and topography data were analyzed by RS and GIS. Fifth-through seventh-order rivers were studied. Morphometric analysis assessed the area’s flash flood danger. NEOM has 14 catchments. We determined each catchment’s area, perimeter, maximum length, total stream length, minimum and maximum elevations. It also uses remote sensing. It classifies Landsat 8 photos for land use and cover maps. Image categorization involves high-quality Landsat satellite images and secondary data, plus user experience and knowledge. This study used the wetness index, elevation, slope, stream power index, topographic roughness index, normalized difference vegetation index, sediment transport index, stream order, flow accumulation, and geological formation. Analytic hierarchy considered all earlier criteria (AHP). The geometric consistency index GCI (0.15) and the consistency ratio CR (4.3%) are calculated. The study showed five degrees of flooding risk for Wadi Zawhi and four for Wadi Surr, from very high to very low. 9.16% of Wadi Surr is vulnerable to very high flooding, 50% to high flooding, 40% to low flooding, and 0.3% to very low flooding. Wadi Zawhi’s flood risk is 0.23% high, moderate, low, or extremely low. They’re in Wadi Surr and Wadi Zawhi. Flood mapping helps prepare for emergencies. Flood-prone areas should prioritize resilience.展开更多
The city of Jeddah, the second major city in the Kingdom of Saudi Arabia (KSA), was severely damaged on November 25, 2009. A deadly and costly flash flood, which can be exacerbated in arid environments, occurred when ...The city of Jeddah, the second major city in the Kingdom of Saudi Arabia (KSA), was severely damaged on November 25, 2009. A deadly and costly flash flood, which can be exacerbated in arid environments, occurred when more than 90 millimetres (3.5 inches) of rain fell in just four hours. A national disaster was declared. This extreme disaster has been a catalyst for attempts to advance our understanding of flash flood events and how to appropriately respond to their destructive nature. One-hundred and twenty people were killed, around 350 others were reported missing and approximately four billion Saudi riyals (one billion US dollars) of damage was caused. Considered to be one of the great of Saudi’s cities, Jeddah is the economic capital of the country. It is the largest coastal town on the west coast, with a population of about 5.1 million and an estimated area of 5460 square kilometres. Based on its rapid urbanisation and population growth, a function of a multitude of parameters, a multi-criterion analysis using AHP and GIS was performed to comprehensively evaluate the environmental quality of the different municipal wards affected by Jeddah’s flash floods. This research presents an analysis of the different factors that caused these flash flood events. The results indicate that the causes of these floods are related to a number of factors that significantly contribute to the worsening of flood disasters.展开更多
Due to global climatic changes, flash floods are followed as a yearly disaster with high magnitude of influence. During the years 1981, 1988, 2010, 2012 and in January 2013, Tabuk city, northwest of Saudi Arabia suffe...Due to global climatic changes, flash floods are followed as a yearly disaster with high magnitude of influence. During the years 1981, 1988, 2010, 2012 and in January 2013, Tabuk city, northwest of Saudi Arabia suffered huge flash floods. These are major factors affecting on the swelling behavior of expansive Tabuk shale. The examined geotechnical properties of the surface and subsurface lithology of the sedimentary deposits distinguished Tabuk city into three zones. The expansive zone is spread in the middle and the non-expansive zones are distributed in the east and west of the city. The Watershed Modeling System (WMS) and Hydrologic Engineering Center (HEC-1) models were used to delineate and identify the drainage system and basin morphometry, where flash floods and accumulation of water might take place. Integration between geotechnical distribution maps of the expansion soil and surface hydrological data in terms of runoff maps was done. It has been identified the whereabouts the soils which have expansion characteristics and areas prone to flooding and surface runoff. They are helpful in defining the hazard zones map. Based on this map, it can be avoided constructions on the risk neighborhoods such as Al Qadsiyah, Al Maseif, Arrwdah, Al Nakhil and Al Rajhi. Also, it can suggest that the western side of Tabuk city is suitable for future urban extension. These results will help planners and citizens to create alternative development scenarios and determine their impact on the future urbanization patterns. Moreover, the direction of surface runoff flow or storm water discharge should be away from the expansion soil areas. Therefore, constructing dams on the outlet of the high-risk basins, south of Tabuk city is an important solution to control flash flood events, as well as increase groundwater recharge.展开更多
基金supported by the Key Project in the National Science and Technology Pillar Program during the Twelfth Five-Year Plan Period(Grant No.2012BAK10B04)the Specific Research Fund of the China Institute of Water Resources and Hydropower Research(Grant No.JZ0145B032014)
文摘Flash flood hazard mapping is a supporting component of non-structural measures for flash flood prevention. Pilot case studies are necessary to develop more practicable methods for the technical support systems of flash flood hazard mapping. In this study, the headwater catchment of the Xiapu River Basin in central China was selected as a pilot study area for flash flood hazard mapping. A conceptual distributed hydrological model was developed for flood calculation based on the framework of the Xinanjiang model, which is widely used in humid and semi-humid regions in China. The developed model employs the geomorphological unit hydrograph method, which is extremely valuable when simulating the overland flow process in ungauged catchments, as compared with the original Xinanjiang model. The model was tested in the pilot study area, and the results agree with the measured data on the whole. After calibration and validation, the model is shown to be a useful tool for flash flood calculation. A practicable method for flash flood hazard mapping using the calculated peak discharge and digital elevation model data was presented, and three levels of flood hazards were classified. The resulting flash flood hazard maps indicate that the method successfully predicts the spatial distribution of flash flood hazards, and it can meet the current requirements in China.
文摘Southern Red Sea flooding is common. Assessing flood-prone development risks helps decrease life and property threats. It tries to improve flood awareness and advocate property owner steps to lessen risk. DEMs and topography data were analyzed by RS and GIS. Fifth-through seventh-order rivers were studied. Morphometric analysis assessed the area’s flash flood danger. NEOM has 14 catchments. We determined each catchment’s area, perimeter, maximum length, total stream length, minimum and maximum elevations. It also uses remote sensing. It classifies Landsat 8 photos for land use and cover maps. Image categorization involves high-quality Landsat satellite images and secondary data, plus user experience and knowledge. This study used the wetness index, elevation, slope, stream power index, topographic roughness index, normalized difference vegetation index, sediment transport index, stream order, flow accumulation, and geological formation. Analytic hierarchy considered all earlier criteria (AHP). The geometric consistency index GCI (0.15) and the consistency ratio CR (4.3%) are calculated. The study showed five degrees of flooding risk for Wadi Zawhi and four for Wadi Surr, from very high to very low. 9.16% of Wadi Surr is vulnerable to very high flooding, 50% to high flooding, 40% to low flooding, and 0.3% to very low flooding. Wadi Zawhi’s flood risk is 0.23% high, moderate, low, or extremely low. They’re in Wadi Surr and Wadi Zawhi. Flood mapping helps prepare for emergencies. Flood-prone areas should prioritize resilience.
文摘The city of Jeddah, the second major city in the Kingdom of Saudi Arabia (KSA), was severely damaged on November 25, 2009. A deadly and costly flash flood, which can be exacerbated in arid environments, occurred when more than 90 millimetres (3.5 inches) of rain fell in just four hours. A national disaster was declared. This extreme disaster has been a catalyst for attempts to advance our understanding of flash flood events and how to appropriately respond to their destructive nature. One-hundred and twenty people were killed, around 350 others were reported missing and approximately four billion Saudi riyals (one billion US dollars) of damage was caused. Considered to be one of the great of Saudi’s cities, Jeddah is the economic capital of the country. It is the largest coastal town on the west coast, with a population of about 5.1 million and an estimated area of 5460 square kilometres. Based on its rapid urbanisation and population growth, a function of a multitude of parameters, a multi-criterion analysis using AHP and GIS was performed to comprehensively evaluate the environmental quality of the different municipal wards affected by Jeddah’s flash floods. This research presents an analysis of the different factors that caused these flash flood events. The results indicate that the causes of these floods are related to a number of factors that significantly contribute to the worsening of flood disasters.
文摘Due to global climatic changes, flash floods are followed as a yearly disaster with high magnitude of influence. During the years 1981, 1988, 2010, 2012 and in January 2013, Tabuk city, northwest of Saudi Arabia suffered huge flash floods. These are major factors affecting on the swelling behavior of expansive Tabuk shale. The examined geotechnical properties of the surface and subsurface lithology of the sedimentary deposits distinguished Tabuk city into three zones. The expansive zone is spread in the middle and the non-expansive zones are distributed in the east and west of the city. The Watershed Modeling System (WMS) and Hydrologic Engineering Center (HEC-1) models were used to delineate and identify the drainage system and basin morphometry, where flash floods and accumulation of water might take place. Integration between geotechnical distribution maps of the expansion soil and surface hydrological data in terms of runoff maps was done. It has been identified the whereabouts the soils which have expansion characteristics and areas prone to flooding and surface runoff. They are helpful in defining the hazard zones map. Based on this map, it can be avoided constructions on the risk neighborhoods such as Al Qadsiyah, Al Maseif, Arrwdah, Al Nakhil and Al Rajhi. Also, it can suggest that the western side of Tabuk city is suitable for future urban extension. These results will help planners and citizens to create alternative development scenarios and determine their impact on the future urbanization patterns. Moreover, the direction of surface runoff flow or storm water discharge should be away from the expansion soil areas. Therefore, constructing dams on the outlet of the high-risk basins, south of Tabuk city is an important solution to control flash flood events, as well as increase groundwater recharge.
