Flood Hazard Index Research Articles

Large-scale flood hazard assessment under climate change: A case study

Climate change represents a set of mechanisms that result in significant impacts toward hydrologic processes both at global and regional scales and usually they are developing countries where face the most challenging consequences. For instance, arid and semi-arid environments experience a high level of uncertainty in rainfall, which results in unforeseen periods of droughts, or high-intensity rainfall, which generates severe floods, increasing the water insecurity and flood damage in these areas. Climate pattern variations are specifically critical to forecast conditions for flood hazard management. General Circulation Models (GCMs) are useful tools to forecast future climate change scenarios. However, the application of GCM in flood hazard management is particularly challenging, given that they operate under high uncertainty and coarse scale. In this context, a five-class Flood Hazard Index (FHI) map was generated by using a multi criteria index approach, based on defining the greater influence of seven factors related to flood generation: runoff coefficient, elevation, slope, distance from the drainage network, rainfall intensity, soil erosion and land use. In this paper, we utilized monthly data for the baseline period (1980–2004), and then the output of 8 GCMs for surface air temperature (SAT) and precipitation were downscaled using a statistical model and evaluated in the baseline period. Consequently, the most suitable models were selected according to their average monthly performance. The Soil and Water Assessment Tool (SWAT) was then used to develop a runoff coefficient map, using the downscaled outputs of the selected GCMs. Accordingly, a flood hazard model was developed at a large basin in the northeast of Iran for baseline and future periods (2040–2064) under RCP 8.5 emission scenarios. Having validated the generated flood map for the baseline period, the future maps were generated and compared. Results show the increase in temperature and decrease in precipitation; however, it was found that rainfall intensities are to be increased. This supports the final flood hazard map for the future climate conditions scenario with an increased relative hazard level. This was particularly observed in flat, and moderate sloped areas, compared to the model results with historic climate data.

Flash flood hazard areas assessment in Bandar Negeri Suoh (BNS) region using an index based approaches and analytical hierarchy process

Flash flood led to high levels of water in the urban areas, causing many problems such as bridge collapse, building damage and the victim died. It is impossible to avoid risks of floods or prevent their occurrence, however, it is plausible to work on the reduction of their effects and to reduce the losses which they may cause. The objective of this paper is to generate a flash flood map in Suoh region, using satellite images, UAVs images and GIS tools. Analytical Hierarchical Process is used to determine the relative impact weight of flood causative factors to get a composite Flood Hazard Index (FHI). The causative factors in this study are flow accumulation (F), rainfall intensity (I), geology (G), land use (U), slope (S), and elevation (E). The presented methodology has been applied to an area in Suoh region, where recurring flood events have appeared. Initially, FIGUSE method resulted in an FHI and a corresponding flood map. A sensitivity analysis on the parameter’s values revealed some interesting information on the relative importance of each criterion, presented and commented in the discussion section.

Application of the GIS based multi-criteria decision analysis and analytical hierarchy process (AHP) in the flood susceptibility mapping (Tunisia)

Flooding is considered as the most dangerous natural catastrophe in the world. This paper develops a spatial multi-criteria decision production prototype for the evaluation of flooding susceptibility for the city of Tunis. Eight criterions were considered in order to identify and assess the spatial distribution of hazardous zones and were integrated in the Geographical Information System (ArcGIS). The analytical hierarchy process (AHP) is a mathematical technique for flood hazard modeling and decision support based on the weight and rank of each flood factor in order to calculate Flood Hazard Index (FHI) to generate a flood susceptibility map. This was classified from very low to very high classes flood potential. Five classes are observed: 2.85% (very low), 7.5% (low), 17.95% (moderate), 20.63% (high), and 51.06% (very high). FHI was coupled with a sensitivity analysis to derive the Flood Hazard Index with sensitivity (FHIS). This index evaluates the effect of each criteria which allows for better assessment of the role of each parameter in flood susceptibility. The results of this study provide a basis to limit the impacts of flood and protect urban zone against inundation.

A geospatial approach to flash flood hazard mapping in the city of Warangal, Telangana, India

Abstract Dense urbanization leading to uncontrolled transformations within settlements result in flash flooding with overflowing drains leading to a greater inconvenience for the public and damage to private properties. Hence mapping of flash floods would be useful in identifying the high-risk flood zones for disaster response and urban services, during emergencies with rainfall events of high intensity. This article aims to prepare a flood hazard map of Warangal Municipal Corporation (WMC) in Telangana State, India. WMC is chronically affected due to a rise in water levels resulting in flash floods, with an increase in encroachments. The factors considered in this study are rainfall (curve number), surface slope and surface roughness, type of soil, and distance to main channel, drainage density, and land use cover. To decide the relative weight of the impact of each flood causative factors an Analytical Hierarchical Process (AHP) was used. Accordingly, a composite Flood Hazard Index (FHI) has been derived by using the multiple-criteria decision-making tools by integrating these into a Geographical Information System (GIS). The Soil and Water Assessment Tool (SWAT) in Quantum GIS (QGIS), which is a hydrological model, was used to evaluate the projection of streamflow over the water basin and model parameters were optimized using water balance equations during calibration and validation periods.

Assessing flood risk using analytical hierarchy process (AHP) and geographical information system (GIS): application in Coochbehar district of West Bengal, India

Floods are recurrent events in the floodplains of Coochbehar district inundating and damaging considerable quantities of standing crops and hampering the livelihoods of thousands of peoples. This paper addresses an efficient and reliable methodology for preparing flood risk map for the Coochbehar district based on two essential concepts of hazard and vulnerability. With the aid of analytical hierarchy process, a variety of hazard and vulnerability defining criteria have been weighted according to their contributions and were further processed in the geographical information system environment to observe and assess spatial characters of flood hazard index (FHI) and flood vulnerability index (FVI) that collectively have defined the flood risk index (FRI). Accordingly, the eastern, southeastern, southern, central and north-central parts of the district are prone to frequent floods while vulnerability levels are higher at areas locating particularly along the India-Bangladesh international border in the south, southeast and southwest and in some isolated clusters in the central and north-central parts. The influences of these FHI and FVI in shaping the FRI distribution were observed to be varying at places. The Tufanganj subdivision is found to be the least safe administrative unit followed by the Coochbehar Sadar, Mathabhanga and Dinhata subdivisions. The rest, i.e., the Mekliganj subdivision is observed to be relatively safe but is not immune at all. The flood risk distribution yielded the information of 58 (4.91%) settlements with higher FRI scores followed by 145 (12.29%) villages/towns with moderate and 456 (38.64%) villages/towns under low flooding risks.

GIS-based MCDM – AHP modeling for flood susceptibility mapping of arid areas, southeastern Tunisia

Floods are considered as a major natural disaster due to their devastating effects that lead to socio-economic losses. The present study is an attempt to prepare a flood hazard susceptibility map of the Gabes region using ‘multi-criteria decision making – analytical hierarchy process’ model in geographic information system environment. Eight factors have been used in the flood modeling: elevation, land use/land cover, lithology, rainfall intensity, drainage density, distance from the drainage network, slope, and groundwater depth. The impact of each factor contributing in the flood risk was examined by weights using analytical hierarchy process method. The results obtained shows that the most prominent flood occurrence factor is the elevation (22.5%), around 15% of the total area is flooded and the flood hazard index is equal 6.30. The validation of results by a susceptibility zones histogram showed that 74.51% of the observed flood areas are mainly concentrated in a moderate to very high susceptibility zone.

Coastal Flood Assessment due to Sea Level Rise and Extreme Storm Events: A Case Study of the Atlantic Coast of Portugal’s Mainland

Portugal’s mainland has hundreds of thousands of people living in the Atlantic coastal zone, with numerous high economic value activities and a high number of infrastructures that must be adapted and protected from natural coastal hazards, namely, extreme storms and sea level rise (SLR). In the context of climate change adaptation strategies, a reliable and accurate assessment of the physical vulnerability to SLR is crucial. This study is a contribution to the implementation of flooding standards imposed by the European Directive 2007/60/EC, which requires each member state to assess the risk associated to SLR and floods caused by extreme events. Therefore, coastal hazard on the Atlantic Coast of Portugal’s mainland was evaluated for 2025, 2050, and 2100 over the whole extension due to SLR, with different sea level scenarios for different extreme event return periods. A coastal probabilistic flooding map was produced based on the developed probabilistic cartography methodology using geographic information system (GIS) technology. The Extreme Flood Hazard Index (EFHI) was determined on probabilistic flood bases using five probability intervals of 20% amplitude. For a given SLR scenario, the EFHI is expressed, on the probabilistic flooding maps for an extreme tidal maximum level, by five hazard classes ranging from 1 (Very Low) to 5 (Extreme).

A methodology for urban micro-scale coastal flood vulnerability and risk assessment and mapping

One of the most dangerous challenges to settlements in the UK comes from flooding. Currently, there is extensive map coverage of flood hazards zones in the UK; however, it is increasingly recognised that risk associated with natural hazards cannot be reduced solely by focussing on the hazard. There is also an urgent need for methods of evaluating and mapping flood vulnerability and risk in detail. Despite its significance, conventional flood risk assessment methodologies often underestimate likely levels of vulnerability in areas prone to hazards, yet it is the degree of vulnerability within a community that determines the consequences of any given hazard. The research presented proposes a general methodology to assess and map Coastal Flood Vulnerability and Risk at a detailed, micro-scale level. This captures aspects that are considered crucial and representative of reality (socio-economic, physical and resilient features). The methodology is then applied to a UK case study (city of Portsmouth). Environment Agency flood hazard data, National Census socio-economic data and Ordnance Survey topographic map data have been used to evaluate and map coastal flood vulnerability, examining neighbourhoods within census wards. This led to a subsequent analysis of Coastal Flood Risk, via the combination of a Coastal Flood Vulnerability Index and a Coastal Flood Hazard Index, for the Portsmouth ward Hilsea. This, consequently, identifies potential weaknesses that could lead to more effective targeting of interventions to improve resilience and reduce vulnerability in the long term and provides a basis for hazard and environmental managers/planners to generate comprehensive national/international vulnerability and risk assessments.

River basin-scale flood hazard assessment using a modified multi-criteria decision analysis approach: A case study

Flood is a major natural hazard with extremely large impact on social-ecological systems. Therefore, developing reliable and efficient tools to identify areas vulnerable to potential flooding is vital for water managers, engineers and decision makers. Moreover, being able to accurately classify the level of hazard is a step forward towards more efficient flood hazard mapping. This study presents a multi-criteria index approach to classify potential flood hazards at the river basin scale. The presented methodology was implemented in the Mashhad Plain basin in North-east Iran, where flood has been a major issue in the last few decades. In the present study, seven factors, selected based on their greater influence towards flooding, were identified and extracted from the basic thematic layers to be used to generate a five-class Flood Hazard Index (FHI) map. The Soil and Water Assessment Tool (SWAT) was used to develop a runoff coefficient map, which was found to be the most influential factor. A sensitivity analysis was performed and the results incorporated to generate a modified Flood Hazard Index (mFHI) map. The accuracy of the proposed method was evaluated against the well-documented flood records in the last 42 years at the study area. The results showed that, for both FHI and mFHI maps, more than 97% of historical flood events have occurred in moderate to very high flood hazard areas. This demonstrates that incorporating hydrological model (such as SWAT) and multi-criteria analysis introduces a robust methodology to generate comprehensive potential flood hazard maps. Moreover, the proposed modified methodology can be used to identify high potential flood hazard zones and work towards more efficient flood management and mitigation strategies.

Flood Hazard Mapping and Assessment on the Angkor World Heritage Site, Cambodia

World Heritage sites in general are exposed to the impacts of natural hazards, which threaten their integrity and may compromise their value. Floods are a severe threat to the Angkor World Heritage site. Studies of regional floods and flood hazard zoning have played an increasingly important role in ensuring sustainability of the Angkor site. This study developed a flood hazard index (FHI) model based on a geographic information system (GIS) and used synthetic aperture radar (SAR) data to extract historical floods at Angkor from 2007 to 2013. Four indices (flood affected frequency, absolute elevation, elevation standard deviation, drainage density) were used to identify flood-prone areas. The Analytic Hierarchy Process (AHP) and the Delphi method were employed to determine the weight of each index. The weighted indices were then used to develop a distribution map of flood hazards at Angkor. The results show that 9 monuments are at risk by potential floods among the 52 components of the Angkor monuments. The high hazard and moderate-to-high hazard areas in the core zone are mainly located surrounding the West Baray but will not bring direct risk impact on the monuments located in the core archaeological zone. The moderate hazard areas are located on both sides of the Siem Reap and Roluos rivers and in the flooded area of the Tonle Sap Lake in the core archaeological zone. These areas cover 19.4 km2, accounting for 9.13% of the total area of the core zone. This moderate hazard zone poses a greater flood threat to the core zone and must be given higher attention. The buffer zone is a small area with fewer sites. As such, flooding has a low impact on the buffer zone. The methods used in this study can be applied to flood hazard assessments of other heritage sites in Southeast Asia.

Flood hazard assessment of August 20, 2016 floods in Satna District, Madhya Pradesh, India

Floods are one of the most destructive and land sculpting phenomena around the globe and different aspects of them are being studied at different spatial and temporal scales. Magnitude and frequency of floods, the two important components in flood studies, have been studied with enhanced accuracy and quickness because of commencement and advancement in geospatial technology. Accentuation in the studies of floods and hazardous impacts thereof, at different temporal and spatial scales, have been achieved due to increased temporal and spatial resolution of remotely sensed satellite images. Advancement in computational power has also helped us to perform such analysis quickly. Even after such enhanced capabilities and facilities, flood studies at local levels (village or town) are not very common. Lack of such studies poses a serious challenge to hydrologists, climate scientists, geoscientists, planners and policy makers. The present work proceeds to achieve twofold objectives to ease the challenge faced: 1) to assess the flood hazard of August 20, 2016 flood event of Satna district of Madhya Pradesh at village/town level; and 2) to devise a flood hazard index (FHI) using linear combination of only two parameters i.e. flooded area and qualitative turbidity. The flooded areas have been derived from Landsat 8 OLI-TIRS image of August 20, 2016 using tasseled cap wetness index and modified normalised difference water index (MNDWI). The values of MNDWI have been taken as a proxy for qualitative turbidity. Association of FHI with flood-affected arable land and built-up area is positive and statistically significant at 0.01 level that justified the method of FHI computation. As compared to the four parameters-based FHI, devised by Kumar (2016), this study found that the FHI computed with only two parameters is also effective, easy to compute and this approach may be tested in other flood-affected parts of the globe.

Development of Flash Flood Hazard Map in Bima City (NTB) using Analytical Hierarchy Process

Flash flood is one of the hydro-meteorological hazards that often occurs in Indonesia. Some major factors affecting this hazard are high topography and weak soil structure. Every incident of flash flood has caused losses in the form of damage to infrastructure, victims, and the other losses. Therefore, flash flood hazard areas should be mapped so that community and local government can anticipate the event during heavy rainfall. This study developed a flash flood hazard index using a decision-making model, with approach of the Analytic Hierarchy Process (AHP). With this method, four parameters were calculated, namely the distance to the stream channels, slope, cover and soil types. The weight and rank values were assigned to the layers and classes of each layer respectively. A hazard map was obtained using an algorithm that combines factors in weighted linear combinations. The index of flash flood hazard zone with rainfall factor was analysed with sensitivity analysis shows better result since 13 of 16 flash flood points (81.25%) are in high vulnerability to flooding.

Integration of multi-parametric fuzzy analytic hierarchy process and GIS along the UNESCO World Heritage: a flood hazard index, Mombasa County, Kenya

Flood is a natural hazard affecting human life and ecosystem globally causing catastrophic disasters. Most flood-induced socioeconomic losses are exacerbated by unabated urban development, population upsurge, unregulated municipal systems, and indiscriminate land use. Therefore, implementation of a flood prediction system can potentially help mitigate flood-induced consequences. In this study, a framework of multi-criteria analysis incorporating geographic information system, fuzzy analytic hierarchy process, and bivariate statistics-based methods was developed for flood hazard index determination. Flood-prone areas were identified based on six factors (hydrological aspects and land cover): elevation, aspect, slope, flow accumulation, rainfall, and land cover map. To generate a flood hazard index, each one of the factors was classified into five categories: very low, low, moderate, high, and very high; the factors were then combined and processed using the proposed methodology. Obtained overall maps have been adjusted with socioeconomic data such as gross domestic product to relate the flood exposure to economic and demographic factors in Mombasa County, Kenya. Results suggest that the County is largely dominated by areas with a high flood hazard index due to its location and shoreline. Fort Jesus, the UNESCO World Heritage site, is currently under high risk of flood as shown by the flood hazard index, while most of the shoreline is at very high risk of flooding.

Assessing Flood Hazard at River Basin Scale: Comparison between HECRAS-WMS and Flood Hazard Index (FHI) Methods Applied to El Maleh Basin, Morocco

The cartography of floods by two different approaches enabled us to determine the limits and the advantages of each one of them. This cartography has been applied to the El Maleh basin situated in the South-East of Morocco. The HEC-RAS approach consists of a combination of the surface hydrologic model and the digital terrain model data. This combination allows thereafter the mapping of the flood zones by the use of the WMS software. Thus it can predict the probability occurrence of floods at various frequency times and determine the intensity of the flood (depth and velocity of flood water) inside the El Maleh river by using the existing hydrological data. Otherwise FHI method approach introduces a multi-criteria index to assess flood risk areas in a regional scale. Six parameters (flow accumulation, distance from drainage network, drainage network density, slope, land use, and geology) were used in this last method. The relative importance of each parameter for the occurrence and severity of flood has been connected to weight values. These values are calculated following an Analytical Hierarchy Process: AHP, a method originally developed for the solution of Operational Research problems. According to their weight values, information of the different parameters is superimposed, resulting to flood risk mapping. The use of the WMS model allowed us to accurately map the flood risk areas with precisely flood heights in different levels. However, this method is only applicable for a small portion of the basin located downstream of the hydrological station. Otherwise, the FHI method allows it to map the entire basin but without giving an indication of the water levels reached by floods. One method does not exclude the other since both approaches provide important information for flood risk assessment.

Characterizing flood hazard risk in data-scarce areas, using a remote sensing and GIS-based flood hazard index

The frequency in occurrence and severity of floods has increased globally. However, many regions around the globe, especially in developing countries, lack the necessary field monitoring data to characterize flood hazard risk. This paper puts forward methodology for developing flood hazard maps that define flood hazard risk, using a remote sensing and GIS-based flood hazard index (FHI), for the Nyamwamba watershed in western Uganda. The FHI was compiled using analytical hierarchy process and considered slope, flow accumulation, drainage network density, distance from drainage channel, geology, land use/cover and rainfall intensity as the flood causative factors. These factors were derived from Landsat, SRTM and PERSIANN remote sensing data products, except for geology that requires field data. The resultant composite FHI yielded a flood hazard map pointing out that over 11 and 18% of the study area was very highly and highly susceptible to flooding, respectively, while the remaining area ranged from medium to very low risk. The resulting flood hazard map was further verified using inundation area of a historical flood event in the study area. The proposed methodology was effective in producing a flood hazard map at the watershed local scale, in a data-scarce region, useful in devising flood mitigation measures.

Flood risk assessment and mapping based on a modified multi-parameter flood hazard index model in the Guanzhong Urban Area, China

The aim of this study is to promote appropriate land development policies and to improve operations of flood risk in urban areas. This study first illustrated a multi-parameter flood hazard index (FHI) model for assessing potential flood risk areas in the Guanzhong Urban Area (GUA), a large-scale urban area in northwestern China. The FHI model consisted of the following seven parameters: rainfall intensity, flow accumulation, distance from the river network, elevation, land use, surface slope, and geology. The parameter weights were assigned using an analytical hierarchy process and the sum weight of the first three parameters accounted for 71.21% of the total weight and had significant influence on flooding. By combining with population factor, the FHI model was modified to estimate the flood control area in the GUA. The spatial distribution of the flood risk was obviously different in the flood hazard area and flood control area. The very low risk and medium risk area in the flood control area increased by 11.19% and reduced by 9.03% compared to flood hazard area, but there were no obvious differences in other levels of risk areas. The flood control assessment indicated that very high flood risk areas were principally concentrated along river banks (the Weihe River and its tributaries) and in the middle of the Guanzhong Plain. Land use and population distribution are related to flooding. Especially, forestland was located in 84.48% of the very low risk area, while low risk areas were mainly located in 91.49% of high population dispersion area.

Application of Multi-parametric AHP for Flood Hazard Zonation in Coastal Lowland Area of Central Vietnam

Flooding is one of the most commonly occurring natural hazards worldwide. Multiple geomorphic factors such as elevation, slope, topographic wetness index and distance from the river channel impact on flood susceptibility. Determining the effect of each factor and integration of their influence on flood hazard zonation has become an essential need in flood management. This study attempts to develop a hierarchical model for flood hazard zonation in the coastal lowland of Central Vietnam by using a multi-parametric approach. Five factors including elevation based flood inundation, distance from the river channel, land use, slope and topographic wetness index have been taken into consideration for developing flood hazard zonation. The Analytical Hierarchy Process (AHP) method was applied to assign weights according to the pair-wise comparisons of the parameters. These weights were used for calculation of Flood Hazard Index which was then evaluated and classified into four zones of flood hazard susceptibility. The result of flood hazard zonation was compared with field survey flood pillar points and flood inundation map extracted from ALOS PALSAR image in 2007 for validation. The comparison with field flood pillars indicated good correspondence with demarcated zones and estimated depth. Further, nearly 80 percent of inundated areas observed in ALOS PALSAR data fall in the high and very high flood hazard zones. The excellent agreement between flood hazard zonation map and observed inundation demonstrate the effectiveness AHP based method in flood hazard assessment.

Evaluation of Climate Change Impact And Groundwater Vulnerability Assessment In Rangpur District, Bangladesh

Groundwater vulnerability assessment was carried out in Rangpur district due to climate change and with an aim to assess the climatic change evaluation and groundwater vulnerability. The climatic parameter such as rainfall and temperature were used to evaluate the changes of climate. Moisture index, drought hazard index, flood hazard index and groundwater vulnerability assessment were calculated following the Thornthwaite model (1948), Shahid and Behrawan (2008) and GIS based DRASTIC model. The analysis reveals that rainfall related flood hazards may increase over the years as the duration and magnitude of rainfall may increase. As temperature of Rangpur may change, so potential evaporation will change. Risk ranking revel that severity and frequency rainfall flood is higher than meteorological drought and the highest flood risk indicate moderate-to-high flood risk condition. The highest meteorological drought risk indicates drought risk condition sufficiently high. Groundwater level is declining at an alarming rate which causing the groundwater moderate vulnerable to high vulnerable condition.

Flood hazard assessment of 2014 floods in Sonawari sub-district of Bandipore district (Jammu&Kashmir): An application of geoinformatics

Massive flooding in the Kashmir valley was induced by heavy rainfall due to combined effects of western disturbances and Indian summer monsoon during September 04–10, 2014. The populous Sonawari sub-district was severely affected by flood waves that caused complete damage to standing crops and disrupted man-made linear structures (embankment, canal, and road network). High value land use classes (cropped land, built-up and plantation), which encroached on swamps and wetlands between 1972 and 2014, were badly damaged. The main aim of this study is to assess flood hazard at village level in the sub-district. Village-wise standardised flood hazard indicators were flood affected areas, mean turbidity, mean flood depth and duration. These indicators were derived from the Landsat 7 ETM+, Landsat 8 OLI-TIRS images and SRTM (30m) DEM. Linear combination of these standardised indicators in GIS environment formulated Flood Hazard Index (FHI). Furthermore, the computed FHI values were divided into four flood hazard zones. Low, moderate, high and very high flood hazard zones occupied 16, 32, 34 and 19% of the total area, respectively. Further, these zones accounted for 21, 23, 33 and 23% of the total number of villages and towns (43), respectively. FHI was validated with overall changes in NDVI values with the help of linear regression model that showed a fair association between village-wise FHI and changes in mean NDVI values as the coefficient of determination (R2) was 0.75 with a least standard error of 0.05. Village-wise flood hazard assessment has immense importance to plan future land use and to implement flood management strategies during pre and post- floods in the sub-district.

A cascading flash flood guidance system: development and application in Yunnan Province, China

Yunnan Province, located in Southwest China, suffers from massive flash flood hazards due to its complex mountainous hydrometeorology. However, traditional flash flood forecasting approaches can hardly provide an effective and comprehensive guide. Aiming to build a multilevel guidance system of flash flood warning for Yunnan, this study develops a Cascading Flash Flood Guidance (CFFG) system, progressively from the Flash Flood Potential Index (FFPI), the Flash Flood Hazard Index (FFHI) to the Flash Flood Risk Index (FFRI). First, land cover and vegetation cover data from MODIS products, the Harmonized World Soil Database soil map, and SRTM slope data are used in generating a composite FFPI map. In this process, an integrated approach of the analytic hierarchy process and the information entropy theory is used as a weighting method. Then, three standardized rainfall amounts (average daily amount in flood seasons, maximum 6 h and maximum 24 h amount) are added to derive FFHI. Further inclusion of GDP, population and flood prevention measures as vulnerability factors for the FFRI enabled prediction of the flash flood risk. The spatial patterns of the CFFG indices indicate that counties in east Yunnan are most susceptible to flash floods, which agrees with the distribution of observed flash flood events. Compared to other approaches, the CFFG system could be a useful prototype in mapping characteristics of China’s flash floods in a cascading manner (i.e., potential, hazard and risk) for users at different administrative levels (e.g., town, county, province and even nation).