Geospatial Tools for Prevention of Urban Floods Case Study: River of El Maleh (City of Mohammedia – Morocco) (original) (raw)
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Pure and Applied Geophysics, 2016
Many scientists link climate change to the increase of the extreme weather phenomena frequency, which combined with land use changes often lead to disasters with severe social and economic effects. Especially floods as a consequence of heavy rainfall can put vulnerable human and natural systems such as transboundary wetlands at risk. In order to meet the European Directive 2007/60/EC requirements for the development of flood risk management plans, the flood hazard map of Evros transboundary watershed was produced after a grid-based GIS modelling method that aggregates the main factors related to the development of floods: topography, land use, geology, slope, flow accumulation and rainfall intensity. The verification of this tool was achieved through the comparison between the produced hazard map and the inundation maps derived from the supervised classification of Landsat 5 and 7 satellite imageries of four flood events that took place at Evros delta proximity, a wetland of international importance. The comparison of the modelled output (high and very high flood hazard areas) with the extent of the inundated areas as mapped from the satellite data indicated the satisfactory performance of the model. Furthermore, the vulnerability of each land use against the flood events was examined. Geographically Weighted Regression has also been applied between the final flood hazard map and the major factors in order to ascertain their contribution to flood events. The results accredited the existence of a strong relationship between land uses and flood hazard indicating the flood susceptibility of the lowlands and agricultural land. A dynamic transboundary flood hazard management plan should be developed in order to meet the Flood Directive requirements for adequate and coordinated mitigation practices to reduce flood risk.
2016
Morocco, dueto its geographical location, is exposed to different types of phenomena: climatic, meteorological, geological, etc. We also distinguish so-called major risks such as earthquakes, landslides, droughts, floods, and tsunamis. Natural hazards have experienced impressive increases (1950: 24 occurrences, 2015: 377 occurrences), resulting mainly from the density of risk areas occupancy, likely to hazards or disastrous events. These zones with potential risks lead to dramatic disasters, causedamage to goods, combine fatal losses to human lives, and eventually cripple the socio-economic development of the regions. In particular, the phenomenon of floods in Morocco began to be felt more strongly during the last two decades, due on the one handto population growth, economic growth and urban development, agricultural, industrial and tourism which entail a growing occupation of vulnerable areas and on the other hand, the worsening of extreme phenomena (drought and floods) due to cli...
Floods Simulation for Arid City Using GIS and HEC RAS: Case of M’chouneche South-East of Algeria
International Journal of Innovative Studies in Sociology and Humanities, 2023
The study of floods is a topic of increasing interest in the field of risk management because it constitutes the most recurring natural disaster in the world that causes significant damage. Algeria is among the Mediterranean countries that are affected by sudden and unpredictable floods. According to the Algerian civil protection services, one out of three municipalities is likely to be flooded, in part or in full. In recent decades, extreme hydrological events have occurred in the arid city of M'chouneche. Their high frequency and dependence on climate change, in addition to the increasing demographic pressure on the shores of valleys, make them a cause for concern and difficult to manage. The use of empirical, hydrodynamic, or conceptual models and geographical information systems (GIS) has become a valuable approach for assessing natural hazards, especially floods. This work aims to simulate floods for a 10-year and 100-year return periods with a one-dimensional (1-D) model using HEC RAS (Hydrologic Engineering Centers River Analysis System) software, GIS (Geographic Information System), and remote sensing (RS). The result is a decision support tool for local authorities based on feedback experience from extreme hydrological events and flood frequency analysis for different return periods to identify probable flood scenarios and provide valuable decision support for emergency response and crisis management.
Developing a GIS tool to assess potential damage of future floods
Risk Analysis VII, 2010
The evaluation of potential damage of future floods is an essential part of flood management project appraisals. Analysis results reliability is an important issue when comparing flood risk reduction project scenarios. Geographic Information System (GIS) technology plays a crucial role on flood risk analyses. On one hand, the evaluation process requires data on flood hazard and on vulnerability of assets at risk, both spatial data. On the other hand, this data must be combined in order to evaluate flood risk. Even though the role of GIS is central in the evaluation process, GIS software does not offer specific tools for achieving flood damage analysis. The use of standard methods for assessing and combining different data influences accuracy and comparability of evaluation results. Few countries in the world have developed national standard methods to assess flood damage potential. The construction of GIS-based methodologies and GIS models can be the first step toward standardisation of the whole evaluation process. In this purpose, this article presents the development of a GIS tool for evaluating future flood damage potential: F.R.A. GIS tool extension, for use with ArcGIS (ESRI). It first explains how GIS technology is used in flood risk analysis procedures. Then, the tool pre-and post-functions as well as structure of the model are detailed. Finally, a brief case study is presented in order to illustrate the functionalities of the model developed in this article. The methodology described here can be used to guide analysts on the realisation or the automation of flood risk analysis using other GIS software.
Civil Engineering and Architecture, 2022
As a part of climate change; flash floods are rapidly increasing and becoming more severe, challenging more and more cities around the world. According to the recent facts published by the UN and the WHO, their risk increases particularly in low- and mid-income countries, where it exceeds the ability of communities to cope with it. This sheds the light on the importance of the community’s pre-impact conditions, which determine its vulnerability to floods. This research develops a vulnerability assessment tool and its associated methodology as an effective tool to be integrated into the strategic planning of existing cities facing flash floods. It is an indicators-based GIS tool to Assess Physical and Social vulnerability. Nuweiba city on the gulf of Aqaba-Egypt was chosen as a case study. However, it is located in an arid zone, and suffers from frequent and severe flash floods. It could be considered the effluent of Wadi Watir's main watershed (3509 km2). A GIS model has been developed to apply the Physical part of the developed assessment tool. So, Detailed data on the city’s urban structure, DEM and satellite images were integrated and processed to extract the evaluated layer for each vulnerability indicator. Then, a weighted overlay of these indicators was applied to produce the final vulnerability map. The results showed a high level of applicability for the developed model, however, the vulnerability map was compared to the available strategic plan for the city. Accordingly, several changes to the plan were recommended to achieve a more sustainable future for the city.
Geospatial analysis of river flood hazard assessment
E3S Web of Conferences
Floods are one of the most damaging natural disasters which occur frequently in the world. They occur every year in Malaysia due to higher precipitation rates, river meandering, and heavily populated suburban areas. Monsoon rains are the major cause of floods and occur two times per year. The heavy floods in the Kelantan River Basin have shown an increasing trend in recent years. Terrain characteristics of the land and meteorological properties of the region are the main natural factors for this disaster. In this study, the Kuala Krai district of the Kelantan River is selected to be reviewed as the case study for flood risk analysis. Geographical Information System (GIS) integrated with Multicriteria Decision Analysis (MCDA) can be used to evaluate the potential flood risk areas. Historically flooded areas can be extracted from the satellite images to determine flood causing factors for the analysis. At the end of the study, a map of flood risk areas can be generated and validated t...
Advances in Remote Sensing
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.
Flood risk mapping forms the basis for disaster risk management and the associated decision-making systems. The effectiveness of this process is highly dependent on the quality of the input data of both hazard and vulnerability maps and the method utilized. On the one hand, for higher-quality hazard maps, the use of 2D models is generally suggested. However, in ungauged regions, such usage becomes a difficult task, especially at the microscale. On the other hand, vulnerability mapping at the microscale suffers limitations as a result of the failure to consider vulnerability components, the low spatial resolution of the input data, and the omission of urban planning aspects that have crucial impacts on the resulting quality. This paper aims to enhance the quality of both hazard and vulnerability maps at the urban microscale in ungauged regions. The proposed methodology integrates remote sensing data and high-quality city strategic plans (CSPs) using geographic information systems (GISs), a 2D rainfall-runoff-inundation (RRI) simulation model, and multicriteria decision-making analysis (MCDA, i.e., the analytic hierarchy process (AHP)). This method was implemented in Hurghada, Egypt, which from 1996 to 2019 was prone to several urban flood events. Current and future physical, social, and economic vulnerability maps were produced based on seven indicators (land use, building height, building conditions, building materials, total population, population density, and land value). The total vulnerability maps were combined with the hazard maps based on the Kron equation for three different return periods (REPs) 50, 10, and 5 years to create the corresponding flood risk maps. In general, this integrated methodology proved to be an economical tool to overcome the scarcity of data, to fill the gap between urban planning and flood risk management (FRM), and to produce comprehensive and high-quality flood risk maps that aid decision-making systems.
GIS-Based Spatial Mapping of Flash Flood Hazard in Makkah City, Saudi Arabia
Flash floods occur periodically in Makkah city, Saudi Arabia, due to several factors including its rugged topography and geological structures. Hence, precise assessment of floods becomes a more vital demand in development planning. A GIS-based methodology has been developed for quantifying and spatially mapping the flood characteristics. The core of this new approach is integrating several topographic, metrological, geological, and land use datasets in a GIS environment that utilizes the Curve Number (CN) method of flood modelling for ungauged arid catchments. Additionally, the computations of flood quantities, such as depth and volume of runoff, are performed in the attribute tables of GIS layers, in order to assemble all results in the same environment. The accomplished results show that the runoff depth in Makkah, using a 50-years return period, range from 128.1 mm to 193.9 mm while the peak discharge vary from 1063 m 3 /s to 4489 m 3 /s. The total flood volume is expected to reach 172.97 million m 3 over Makkah metropolitan area. The advantages of the developed methodology include precision, cost-effective, digital outputs, and its ability to be re-run in other conditions.