Rainfall Flood Research Articles

A fine construction method of urban road DEM considering road morphological characteristics

Urban road DEM is not only an important basic geographic information data of the city, but also an important element to describe and express the urban topography, and it is an indispensable part of the construction of the smart digital city, urban planning and urban surface process simulation. Previous methods for constructing urban road DEMs do not sufficiently consider the actual morphological characteristics of urban roads, and morphological distortion is evident in the expression of urban roads, seriously affecting the application of urban rainfall flood simulation and urban pipe network design. In response to these problems, this study proposed a considering morphological characteristics fine (CMCF) method of urban road DEM construction, selected a typical urban road area in the Jianye District of Nanjing City in China as the study area, used the 1:500 digital line graphic as data source, hierarchized roads in accordance with different morphological characteristics from the perspective of DEM construction, constructed the corresponding DEMs, and finally merged all levels of road DEMs to produce a complete high-precision urban road DEM. Results showed that the DEM constructed using the CMCF method not only exhibited higher elevation accuracy than the urban road DEM constructed using previous methods, i.e., inverse distance weighting (IDW) and triangulated irregular network (TIN) methods, with a mean error and a root-mean-square error of 0.015 and 0.060, respectively, but it can also accurately express the spatial element composition form and road morphological characteristics of urban roads, avoiding the distorted expression of road morphological characteristics. This study can provide a reference for a new DEM construction method and data support for smart digital city construction and urban surface simulation.

Inundation Resilience Analysis of Metro-Network from a Complex System Perspective Using the Grid Hydrodynamic Model and FBWM Approach: A Case Study of Wuhan

The upward trend of metro flooding disasters inevitably brings new challenges to urban underground flood management. It is essential to evaluate the resilience of metro systems so that efficient flood disaster plans for preparation, emergency response, and timely mitigation may be developed. Traditional response solutions merged multiple sources of data and knowledge to support decision-making. An obvious drawback is that original data sources for evaluations are often stationary, inaccurate, and subjective, owing to the complexity and uncertainty of the metro station’s actual physical environment. Meanwhile, the flood propagation path inside the whole metro station network was prone to be neglected. This paper presents a comprehensive approach to analyzing the resilience of metro networks to solve these problems. Firstly, we designed a simplified weighted and directed metro network module containing six characteristics by a topological approach while considering the slope direction between sites. Subsequently, to estimate the devastating effects and details of the flood hazard on the metro system, a 100-year rainfall–flood scenario simulation was conducted using high-precision DEM and a grid hydrodynamic model to identify the initially above-ground inundated stations (nodes). We developed a dynamic node breakdown algorithm to calculate the inundation sequence of the nodes in the weighted and directed network of the metro. Finally, we analyzed the resilience of the metro network in terms of toughness strength and organization recovery capacity, respectively. The fuzzy best–worst method (FBWM) was developed to obtain the weight of each assessment metric and determine the toughness strength of each node and the entire network. The results were as follows. (1) A simplified three-dimensional metro network based on a complex system perspective was established through a topological approach to explore the resilience of urban subways. (2) A grid hydrodynamic model was developed to accurately and efficiently identify the initially flooded nodes, and a dynamic breakdown algorithm realistically performed the flooding process of the subway network. (3) The node toughness strength was obtained automatically by a nonlinear FBWM method under the constraint of the minimum error to sustain the resilience assessment of the metro network. The research has considerable implications for managing underground flooding and enhancing the resilience of the metro network.

Vulnerability Assessment of Climate Change in Vietnam: A Case Study of Binh Chanh District, Ho Chi Minh City

Climate change poses additional obstacles to poverty eradication and social justice. Rising temperatures, abnormal rainfall increases, storms, floods, and droughts have become more frequent and severe phenomena in Vietnam. This causes serious consequences for the livelihood security of the poor. Binh Chanh district (Ho Chi Minh City) is an area subject to severe risks of climate change in the Mekong River Delta, Vietnam. Here, the low-income groups are the most vulnerable because their adaptive capacity is still limited and low. This study uses the livelihood vulnerability index (LVI) to assess the level of vulnerability to climate change in households and communes in the Binh Chanh district. LVI includes three components: exposure (E), sensitivity (S), and adaptive capacity (AC) based on 23 indicators selected by reviewing the literature and consulting with experts. The article also conducted surveys with 931 households in 16 administrative communes in Binh Chanh for primary data. The research results showed that Tan Kien and An Phu Tay communes have the highest level of vulnerability since they are areas with mainly low-lying terrain and contiguous location rivers; the people in these towns are also vulnerable groups because they do not have a stable source of income, skills, and have low education and experience in climate change adaptation. The study also proposes some solutions to improve the capacity to adapt to climate change of vulnerable communes specifically: 1) creating diversified livelihoods with stable incomes; 2) deploying community-based climate change adaptation models for communes adjacent to rivers; 3) implementing adaptive agriculture and improving social capital for vulnerable households; 4) building resettlement areas for households heavily affected by disasters; and 5) raising awareness among low-income households to respond to natural hazards in the context of climate change.

Parallel Calculation Method for Urban Two-Dimensional Rainfall Flood Model Based on Compute Unified Device Architecture

Parallel Calculation Method for Urban Two-Dimensional Rainfall Flood Model Based on Compute Unified Device Architecture

Evaluation Of Road Channel As A Drainage Function For Agricultural Land Remediation

The Ring Road section on the West Ring Road - Madiun City is an alternative road which connecting the outside of Madiun city to the Madiun city. That road is a road with both side of it is a rice field. As a road, it must be clean from puddles when it rains. So that it does not cause traffic problems in the form of traffic disorder. Bad road channels have an impact on flooding due to rain and make the level of road service in the area decrease. On the other hand, the road channel in the area can also be used as a channel for removing pollutants from agricultural land in the rice fields. So that the process of remediation of agricultural land can run smoothly. This highway channel is highly influenced by the local climate, especially the existing of rainfall. Based on that, there is a need for Adequacy Evaluation of the Roadside of the Rice Fields as a drainage function in Agricultural Land Remediation, with a case study on the Ring Road channel in the West Ring Road - Madiun City. From the results of the analysis in this study, it was found that there are two size of Highway Channel Size on the Ring Road in the West Ring Road - Madiun City and both of them are in good conditions. Channel A1 with size b = 0.71 m, H = 0.36 m and h = 0.11 m. Channel A2 with size b = 0.75 m, H = 0.38 m and h = 0.11 m. The results of the design flood rainfall calculation show that there are variations in values that do not much differ in the return period of 2 years to 25 years and can be used as a reference in the management of small irrigation, drainage systems, and small-scale weir buildings, including calculation of road channels on the Ring Road in the Ring Road Section West-Madiun City. From the analysis, it was found that the road channels on the West Ring Road of Madiun City are still good and adequate. From the analysis of the square and trapezoidal dimensions, it is found that the channel discharge is > the planned discharge, so the dimensions of the channel can accommodate the flood discharge that will occur in a period of 25 years, both as a function of road drainage and as drainage in Agricultural Land Remediation in the rice fields along the road. It is suggested that the need for channel maintenance on the road sections on the Ring Road in the West Ring Road - Madiun City and for further studies regarding other road infrastructure and facilities to support road service levels and as a function for agricultural land drainage

Analyzing the Application of X-Band Radar for Improving Rainfall Observation and Flood Forecasting in Yeongdong, South Korea

The mountainous Yeongdong region of South Korea contains mountains over 1 km. Owing to this topographic blockage, the region has a low-density rain-gauge network, and there is a low-altitude (~1.5 km) observation gap with the nearest large S-band radar. The Korean government installed an X-band dual-polarization radar in 2019 to improve rainfall observations and to prevent hydrological disasters in the Yeongdong region. The present study analyzed rainfall estimates using the newly installed X-band radar to evaluate its hydrological applicability. The rainfall was estimated using a distributed specific differential phase-based technique for a high-resolution 75 m grid. Comparison of the rainfall estimates of the X-band radar and the existing rainfall information showed that the X-band radar was less likely to underestimate rainfall compared to the S-band radar. The accuracy was particularly high within a 10 km observation radius. To evaluate the hydrological applicability of X-band radar rainfall estimates, this study developed a rain-based flood forecasting method—the flow nomograph—for the Samcheok-osib stream, which is vulnerable to heavy rain and resultant floods. This graph represents the flood risk level determined by hydrological–hydraulic modeling with various rainfall scenarios. Rainfall information (X-band radar, S-band radar, ground rain gauge) was applied as input to the flow nomograph to predict the flood level of the stream. Only the X-band radar could accurately predict the actual high-risk increase in the water level for all studied rainfall events.

Depth–Duration–Frequency Relationship Model of Extreme Precipitation in Flood Risk Assessment in the Upper Vistula Basin

The Upper Vistula Basin is a flood-prone region in the summer season (May–October) due to intensive rainfall. From the point of view of water management, it is particularly important to assess the variability in this main factor of flood risk, as well as to establish the depth–duration–frequency (DDF) relationship for maximum precipitation, this having not yet been derived for the region. The analysis of a 68-year (1951–2018) data series of summer maximum precipitation collected by 11 meteorological stations showed the series’ stationarity, which supports the conclusion that there is no increase in the risk of rainfall floods due to the intensification of extreme precipitation. A new approach is proposed for the determination of the DDF relationship, where the best-fitted distribution for each station is selected from among the set of candidate distributions, instead of adopting one fixed distribution for all stations. This approach increases the accuracy of the DDF relationships for individual stations as compared to the commonly used approach. In particular, the traditionally used Gumbel distribution turns out to be not well fitted to the investigated data series, and the advantage of the recently popular GEV distribution is not significant.

Influence of post-pyrogenic successions of the forests of the Urals on the formation of maximum rainfall flood discharges

The issues of losses on the crowns of forest stands in the conditions of forest successions after fires and associated changes in the maximum discharge of rainfall floods are considered. The results of complex field, experimental work, deterministic modelling are presented. It has been established that with the complete burnout of forests in the catchment, the maximum flow rates can increase by 40% compared to the initial state of the forests, and with the restoration of forests, the maximum flow rates of floods again decrease by 15-20% over a 20-year period.

Data analysis reveals that extreme events have increased the flood inundations in the Taquari River´s Valley, southern Brazil

Flood inundations represent more than 62% of the deaths caused by natural disasters in Brazil. The dataset comprises the records of the Encantado´s pluviometric station, a municipality located beside the margin of the Taquari River in southern Brazil, which comprises the rainfall time series (n = 36,466) over 78 years, from April 1943 to December 2020. Complementary datasets also include the annual volume of precipitation per year and the level reached by the Taquari River during 44 flood inundations since 1941. The number of events is subsampled because only 32 years have the complete record of the river level. Three of the five major flood inundations at Encantado occurred after 2001, and the more severe flood recorded the maximum level of the Taquari River (20,27 meters) on July 8th, 2020. Thirty-four percent of all flood inundations in the city were recorded between 2011 and 2020. The months of July to October record 70% of all the events, but there is no record of floods in February and December throughout the data series. The human occupation of the floodplain has been fast in the last decades, and most of the urban area has a potential risk of being affected by flood inundations. Moreover, extreme rainfall events and flood events have been more frequent in the last 30 years. This database can contribute as a starting point for developing predictive models and verifying a possible correlation of floods with extreme events and global climatic changes.

Porous Shallow Water Modeling for Urban Floods in the Zhoushan City, China

Typhoon-induced intense rainfall and urban flooding have endangered the city of Zhoushan every year, urging efficient and accurate flooding prediction. Here, two models (the classical shallow water model that approximates complex buildings by locally refined meshes, and the porous shallow water model that adopts the concept of porosity) are developed and compared for the city of Zhoushan. Specifically, in the porous shallow water model, the building effects on flow storage and conveyance are modeled by the volumetric and edge porosities for each grid, and those on flow resistance are considered by adding extra drag in the flow momentum. Both models are developed under the framework of finite volume method using unstructured triangular grids, along with the Harten-Lax-van Leer-Contact (HLLC) approximate Riemann solver for flux computation and a flexible dry-wet treatment that guarantee model accuracy in dealing with complex flow regimes and topography. The pluvial flooding is simulated during the Super Typhoon Lekima in a 46 km2 mountain-bounded urban area, where efficient and accurate flooding prediction is challenged by local complex building geometry and mountainous topography. It is shown that the computed water depth and flow velocity of the two models agree with each other quite well. For a 2.8-day prediction, the computational cost is 120 min for the porous model using 12 cores of the Intel(R) Xeon(R) Platinum 8173M CPU @ 2.00 GHz processor, whereas it is as high as 17,154 min for the classical shallow water model. It indicates a speed-up of 143 times and sufficient pre-warning time by using the porous shallow water model, without appreciable loss in the quantitative accuracy.

Identifying Storm Hotspots and the Most Unsettled Areas in Barcelona by Analysing Significant Rainfall Episodes from 2013 to 2018

Urban floods repeatedly threaten Barcelona, damaging the city infrastructure and endangering the safety of the population. The urban planning of the city, the socioeconomic distribution, its topography, and the characteristics of precipitation systems translate into these flood events having a heterogeneous effect across the city. It means that the coping capacity has a strong dependence on local factors that must be considered when management plans are developed by the municipality. This work aims to contribute to the better knowledge of precipitation structures associated with heavy rainfall events and floods in Barcelona based on radar data and an urban rain gauge network. Radar data have been provided by the Meteorological Service of Catalonia (SMC), while precipitation data, impact data, and early warnings, have been provided by Barcelona Cicle de l’Aigua S.A. (BCASA), for the period 2013–2018. A new radar-based methodology has been developed to identify convective rainfall structures from radar reflectivity volumes (CAPPI and TOP products) to make the analysis easier. The high computing speed of the procedure allows efficient analysis of a large set of convective cells without scarifying temporal resolution of radar data. Both rainfall fields (radar and rain gauge, respectively) have been compared. Then through the identified rainfall convective structures, thunderstorm hotspots have been identified. Considering an alert indicator from BCASA and the reported incidents, episodes with the highest impact have been analysed in depth. Results show 207 significant rainfall episodes in the ROI for the six years, which are mainly concentrated between September and November. The fact that significant episodes are usually produced by highly convective rain corroborates the advantage of using radar images as a tool to detect any maxima even when no rain gauge is there. In 64 of the episodes, the level of pre-alert was achieved with a maximum frequency between August and September. The proposed algorithm shows more than 8000 centroids of convective cells from 189 cases. Whilst maximum surface reflectivity over 45 dBZ is more prone to occur near the coastline, the centroids of storm cells tend to concentrate more inland. The final objective is to improve the actions taken by the organisation responsible for managing urban floods, which have seen Barcelona recognised as a model city for flood resilience by the United Nations.

Temporary dependency of parameter sensitivity for different flood types

Abstract Hydrological and climatic data at finer temporal resolutions are considered essential to model hydrological processes, especially for short duration flood events. Parameter transferability is an essential approach to obtain sub-daily hydrological simulations at many regions without sub-daily data. In this study, the objective is to investigate temporary dependency of parameter sensitivity for different flood types, which contributes to research into parameter transferability. This study is conducted in a medium-sized basin using a distributed hydrological model, DHSVM. Thirty-six flood events in the period of 04/12/2006–07/01/2013 in the Jinhua River basin, China, are classified into three flood types (FF: flash flood, SRF: short rainfall flood and LRF: long rainfall flood) by using the fuzzy decision tree method. The results show that SRF is the dominant flood type in the study area, followed by LRF and FF. Runoff simulations of FF and SRF are more sensitive to parameter perturbations than those of LRF. Sensitive parameters are highly dependent on temporal resolutions. The temporary dependency of LRF is the highest, followed by SRF and FF. More attention should be payed to sensitive and highly temporal dependent parameters in a subsequent parameter transfer process. Further study into this result is required to test the applicability.

Influence of retaining method of reservoir foundation pit on construction deformation of surrounding soil

In order to avoid the summer rainfall flood peak and improve the efficiency of rainwater utilization, many cities have put the construction of storage ponds on the agenda. However, the design of the foundation pit of the storage tank mostly adopts the design method of building foundation pit, that is, the foundation pit supporting structure will be dismantled after the main structure construction to a certain extent, so this has resulted in a greater waste of resources. In view of the above reasons, this paper proposes a economical foundation pit supporting structure of underground storage pond. This structure can be used as both retaining structure and pool body structure in the process of foundation pit excavation, which can reduce the waste of materials in the construction process and reduce the project cost. Through the calculation results of MIDAS-GTS software, it can be seen that the optimized structure has a good supporting effect in the process of foundation pit excavation, and can completely replace the temporary supporting structure in the original design scheme. The calculation results can provide reference for similar engineering construction.

Hydrological Risk Management of Urbanized Areas in Framework of the Smart City Concept

The emergence of new technologies, such as blockchain, Big Data, etc., provides fundamentally new opportunities for the formation of distributed databases necessary for assessing and managing hydrological risks in urbanized areas. At the same time, the use of the most modern technologies is based on adequate modeling and forecasting of hydrological processes, which, in the context of climatic changes and poorly predicted meteorological events for the long term, require close attention and understanding. The article deals with the tasks of risk assessment and prevention of damage from hazardous hydrological processes (rainfall floods, floods, mudflows, etc.) in framework of the Smart City Concept. Natural and anthropogenic factors of floods, methods of risk assessment and risk management in flooded areas are discussed. The issues of hazardous hydrological processes predictability and damage assessment are discussed. Sufficiency and effectiveness of the decisions made in the field of minimizing the negative impact of water, sufficiency of forces and means to ensure population safety and economic facilities are assessed on the example of the Kuban River basin.

Hydrological regime and runoff formation of the Chulym river and its analysis

One of the main problems of hydrology is the formation of rainfall floods and the assessment of the hydrological regime of rivers. Analysis of the factors of river runoff formation helps to calculate the main hydrological characteristics even in the river sections not illuminated by field data. One of the regional methods for calculating hydrological characteristics is the calculation of the dependences of runoff characteristics on the physical and geographical factors of the catchment area. Such calculations are based on the results of generalizing the data of hydrometeorological observations in the design area. There is often a need for runoff characteristics in the design section of the river where there are no field data of hydrometric observations, and this problem is considered in the proposed study. This is the first time this approach has been implemented for the Chulym River. This article examines the analysis of the factors of the river runoff of the Chulym river, which makes it possible to make objective calculations of the main hydrological characteristics in the sections of the rivers not illuminated by field observations.

Impact of Large Floods on Water Resources and Infrastructure of Urban Areas in the Amur River Region

This article considers the impact of rainfall floods of the Amur river on the distribution of suspended sediments and the content of heavy metals in the watercourse. It presents measurement data of these parameters for equal flood rise and fall flows. The authors found out that factors like a high proportion of watercourse width to its depth, the presence of large tributaries, and the branching of the river course have the strongest impact on the heterogeneity of the distribution of terrigenous and chemical substances across the length and width of the river. They also identified the key impacts of large floods that transform the river course and have negative effects on the reliability and conditions of waterworks within urban territories.

High‐resolution flood precipitation and streamflow relationships in two US river basins

AbstractRelationships between rainfall and river discharge are important for governing flood characteristics and predicting flood impacts. Previous studies have examined these relationships, but they lacked the high‐resolution precipitation data necessary to analyse rainfall–streamflow correlations for individual flood episodes. The present study addresses this limitation by examining rainfall–streamflow relationships in two topographically and climatically different river basins: the Wabash River basin in Indiana and the Willamette River basin in Oregon, using high‐resolution, sub‐basin precipitation and discharge data. Results show that flood rainfall–streamflow relationships are highly spatially variable on a sub‐basin scale. In the Wabash basin, strong positive correlations exist between rainfall and streamflow near urban areas and slight terrain gradients during flash floods, while weaker correlations between rainfall and streamflow are observed in other areas of the basin and for slow‐rise floods. In the Willamette basin, strong positive slow‐rise flood rainfall–streamflow relationships occur in referenced gauges in the eastern, mountainous part of the basin, while strong negative correlations occur in non‐referenced gauges near reservoirs along the main rivers. Results suggest that in addition to high‐resolution rainfall variability, the influence of urbanization, topography and water management on flood rainfall–streamflow relationships needs to be considered in order to forecast local flood impacts better.

Variations in Flash Flood–Producing Storm Characteristics Associated with Changes in Vertical Velocity in a Future Climate in the Mississippi River Basin

AbstractThe Mississippi River basin (MRB) is a flash flood hotspot receiving the most frequent flash floods and highest average rainfall accumulation of any region in the United States. Given the destruction flash floods cause in the current climate in the MRB, it is critical to understand how they will change in a future, warmer climate in order to prepare for these impacts. Recent work utilizing convection-permitting climate simulations to analyze future precipitation changes in flash flood–producing storms in the United States shows that the MRB experiences the greatest future increase in flash flood rainfall. This result motivates the goal of the present study to better understand the changes to precipitation characteristics and vertical velocity in flash flood–producing storms in the MRB. Specifically, the variations in flash flood–producing storm characteristics related to changes in vertical velocity in the MRB are examined by identifying 484 historical flash flood–producing storms from 2002 and 2013 and studying how they change in a future climate using 4-km convection-permitting simulations under a pseudo–global warming framework. In a future climate, precipitation and runoff increase by 17% and 32%, respectively, in flash flood–producing storms in the MRB. While rainfall increases in all flash flood–producing storms due to similar increases in moisture, it increases the most in storms with the strongest vertical velocity, suggesting that storm dynamics might modulate future changes in rainfall. These results are necessary to predict and prepare for the multifaceted impacts of climate change on flash flood–producing storms in order to create more resilient communities.

Extreme events and conservation of subtidal habitats: Effects of a rainfall flood on coralligenous reefs

The increase of the intensity and frequency of rainfall-dominated flood is considered a main effect of climate change. The present study evaluated the effect of a rainfall flood event on coralligenous reefs. The flooded site was compared to three control sites using a Before/After-Control/Impact (BACI) design. Sites were sampled using the STAR (STAndaRdized coralligenous evaluation procedure) approach and three ecological indices (ESCA, COARSE and ISLA) were calculated.At the disturbed site the number of species per sample, beta diversity, sensitivity levels of assemblages and the values of the three indices were lower after the flooding event, while the same variables did not decrease at the control sites. Algal turf and Dictyotales increased at the disturbed sites after the flood event, while Udoteaceae, erect sponges, bryozoans and Corallium rubrum decreased. This study provides evidence for identifying floods as a further cause of degradation for the coralligenous reef assemblages.

Modelling typhoon-induced extreme river discharges: A case study of Typhoon Hagibis in Japan

Study regionNine first-class rivers on the north-eastern Japanese Pacific Ocean coast. Study focusThis study shows new confirmative data that the Cell Distributed Runoff Model version 3.1.1 (CDRM) calibrated by the Shuffled Complex Evolution optimization method developed at the University of Arizona (SCE-UA) can accurately forecast real-time river discharges induced by extreme typhoon Hagibis. Furthermore, we discuss reasons for the equifinality of three calibrated parameter sets, relative importance of typhoon features for calibration and quantify the relationship of distances between the trajectories of three typhoons and associated river basins. New hydrological insightsAs a result of climate change impacts, record-breaking disasters with unprecedented heavy rainfalls, typhoon intensities and associated extreme river discharges are increasing, making it important to develop the real-time forecasting tools for extreme river discharges during floods. The CDRM accurately projected river mouth discharges from three Japanese typhoons (Hagibis-2019, Roke-2011 and Chataan-2002) using calibrated parameter sets from each typhoon. We found the equifinality issue among the calibrated parameter sets but they showed satisfactory cross-validation results with respect to river mouth hydrographs; that similar typhoon trajectories were more important for calibration than rainfall intensities and central pressures; that this methodology was accurate for typhoons passing within distances lower than 130 km from associated river basins. These findings contribute to developing the real-time forecasting tools for extreme river discharges during unprecedented heavy rainfall floods.