Flood Control Works Research Articles

Flood simulation and impact analysis of Xun River under backwater condition

Abstract The intersection of river channels is easy to cause the backside of the main flow, which greatly influences the change of hydrological conditions of river channels. To study the changing characteristics of river flood under the condition of uplift, a one-dimensional hydrodynamic model was established to simulate the evolution process of river flood under the condition of seeking river uplift. Factors such as distance, height, flood speed, inundation area, inundation depth, and flood speed were selected to analyze the changing rules of the influence of river bullying. The results show that the influence degree of the river following is closely related to the size of the flood. Under the same earthquake magnitude, the backwater distance, backwater height, inundation area, inundation depth, and inundation speed of sub-river flood increase with the increase of flood magnitude, while the flood speed decreases. When the magnitude of the flood is once in 200 years, the flood elements reach the maximum, the reflux distance is 8, 368 m, the reflux height is 3.2 m, and the velocity is reduced by 43.2%. This study can provide relevant data for the flood control work in the Sun River basin and provide a reference for the scheme design of tributary interchanges.

Analysis of Navigation Aid Effectiveness of Tianjin Port Water Depth Signal Tower and Development Protection under New Technical Conditions

The Tianjin Port Water Depth Signal Tower is a navigational aid facility that provides tidal level information. In the last century, it made great contributions to the shipping industry of Tianjin Port and played an indispensable role in local flood control work; However, with the improvement of the accuracy of marine radar sounders, the influence of background lights, the increase of surrounding buildings, and the continuous widening and deepening of navigation channels, it is becoming increasingly rare for ship drivers to obtain tidal level information through their eyes or with the help of telescopes. In addition, whether drivers can obtain tidal level information through these methods is also a topic worthy of attention and research.

Study of Urban Flooding Response under Superstandard Conditions

Superstandard conditions refer to extreme rainfall and river flooding that exceed the flood control system or flood control works. In order to explore the influence of superstandard conditions on urban waterlogging, based on the MIKE FLOOD platform, this paper takes the downtown area of Zhoukou as the research object, and it conducts waterlogging simulation in this area under the extreme rainfall conditions of once in 20 years and once in 50 years combined with the ultra-high water level of the river. The simulation results of inundation depth, inundation range and drainage capacity of a self-flowing river are compared and analyzed. The results show that heavy rainfall is the main cause of waterlogging disaster. When extreme rainfall and river flood occur at the same time, the artesian drainage capacity of the pipeline is seriously affected due to the high water level of the river. The city has a large amount of water, and when the river embankment overflows, it poses a serious threat to the safety of the city.

Pre/Post-Fire Soil Erosion and Evaluation of Check-Dams Effectiveness in Mediterranean Suburban Catchments Based on Field Measurements and Modeling

The present study was conducted in the suburban forest of Thessaloniki city (Seich Sou), which constitutes one of the most significant suburban forests in Greece. In 1997, more than the half of the forest area was destroyed by a wildfire, after which soil erosion and flood control works (check-dams) were constructed in the burned areas. The aim of the study is to estimate the annual soil erosion rate for the last 30 years (pre- and post-fire periods) applying the WaTEM/SEDEM model, in order to investigate the impact of this wildfire on soil erosion, the effectiveness of the flood- and erosion-control works and the level of forest regeneration. It is the first time that WaTEM/SEDEM was calibrated and validated in Greece, taking into account soil erosion records from the 18 check-dams that were constructed in the study area in 2001. The mean annual erosion rate was 0.0419 t/ha/year, 0.998 t/ha/year and 0.08 t/ha/year for the pre-fire period, the first 3 years and 20 years after the fire, respectively. The results showed a very low erosion rate for the pre-fire period, an expected significant increase 3 years after the wildfire and a gradual decrease in the subsequent years until 2021. However, it seems that the post-fire regeneration of the forest has not been fully achieved, since the annual soil erosion rate at the long-term post-fire period is double compared with the pre-fire period. Concerning the check-dams’ effectiveness, it was observed that after 20 years of operation, they were non-silted, and most of them retained a small amount of sediments. This fact could be attributed to multiple factors such as the very thin soil depth, fire severity and catchment geomorphology, though the main reason seems to be the time elapsed between fire occurrence and the check-dams’ construction. The results of this study advance/strengthen the knowledge concerning the pre/post-fire soil erosion processes in already degraded ecosystems, while the calibrated model could serve as a useful tool able to be applied in other Mediterranean catchments of similar characteristics.

Analysis on the Disaster Mechanism of “8.12” Flash Flood in Liulin River Basin

Hubei province is located in the center of China with 56% total area characterized with mountainous area. Thus, flash flood caused by extreme rainfall has become one of the significant obstacles that highly affect the social and economic development of the province. In order to scientifically understand the mechanism of flash flood disasters and provide technological support to the local flood prevention and control work, the IWHR designed and developed a new distributed hydrological model named China-FFMS that can simulate the evolution of natural disasters and make an assessment by setting the flood water sources in line with the flow discharge. The FFMS was further applied to simulate the 8.12 flash flood disaster that occurred in the Liulin county of Hubei province on 12 August (“8.12”) and fed by the data collected from the national flash flood disaster investigation and assessment. The calculated peak flow was 666.22 m3/s with an error of +13% compared with postdisaster investigation data (589 m3/s). The results showed that using a multisourced modelling approach, e.g., mixing spatiotemporal variables and sources, to simulate the flash flood process was able to accurately reproduce the flood process and the consistence of the flow discharge, thereby explaining the underlying reason of the disaster formation and evolution. Regarding the case of the Liulin county, the main factor leading to the disaster was the overlapped peak flow where the Dunne flood peak of three different tributaries from the upper reach met together at the same time. Moreover, the peak flow of the Lianhua river at the downstream of Liulin County also arrived at the same time as the upstream peak, which obstructed the flood progress and increased the damage of the disaster. According to the analysis, several suggestions and recommendations are proposed such as the improvement of the forecast and early warning system of the upstream areas, the optimization of the current flood defense plan, and the enhancement of the residents’ awareness of flash flood disasters.

Temporal variations characteristic of precipitation in the Three Gorges Reservoir area from 1961 to 2016

Abstract As a hot issue, the precipitation characteristics of the Three Gorges Reservoir (TGR) area drew widespread interest from domestic and overseas academic circles. Based on China's surface-based meteorological monthly precipitation data from 1961 to 2016 in the TGR area, the spatial, inter-annual and inter-decadal, and multi-time-scale changes of precipitation in the TGR area are analyzed by using Collaborative Kriging (Co-Kriging, CK) Interpolation, linear regression analysis, Morlet wavelet analysis and 5-year sliding average processing, which provide the reference basis for further discussion on the impact of climate change, flood control and drought relief work in the reservoir area. Research shows that in the past 56 years, the average annual precipitation in most areas of the TGR ranges from 1,000 to 1,200 mm; the variation of precipitation in the TGR area shows a weak decreasing trend, with great fluctuation between year and generation, and the precipitation in each decade has a ‘less-more-less’ changing trend; the annual precipitation in the TGR area has periodic changes on multi-time scales, mainly including 25, 16 and 8 years. The smaller the scale the shorter the average period of precipitation change.

Flood forecasting in urban reservoir using hybrid recurrent neural network

Flood forecasting can provide accurate inferences and early warnings for flood control work during the flood season. Due to the variability of local rainfall and the complexity of geographic conditions, existing prediction methods were unable to accurately predict the flooding process in a particular basin. Additionally, the water level sensor generates a significant amount of noise in the inbound flow data during period measurement. To address these issues, this article proposes a real-time flood forecasting model, which is used to accurately predict flood trends and peak times in the flood period. The model uses a convolution kernel function to smooth out local noise and neighborhood values, minimizing the impact of non-stationary series on the training process while retaining the true evolution of the flood in the original data. In our model, we develop a time series attention mechanism that is used to apply various weights to time series input vectors, such as outflow flow and rainfall from upstream reservoirs, this mechanism also improves the accuracy of short-term series prediction. To obtain additional information about the output of the recurrent neural network layer, we also include a multivariate autoregressive integrated moving average module. This method can add a linear component to the output, allowing the prediction result to adapt to the input period's scale shift. This article develops matching models for interval and full basin floods based on the geographical characteristics of China's urban Reservoir and the river basin, thresholds are established based on the outflow from upstream reservoirs, which enables the flood forecasting system to dynamically adjust model parameters in response to the threshold, it also circumvents the scaling problem inherent in flood time series at various scales. We trained and predicted using 25 different types of floods in Ankang Reservoir from 2010 to 2020. Three on-site real-time forecasts of catastrophic flooding at the Ankang Reservoir were conducted in September 2021 to validate the model's accuracy. The algorithm's efficiency in forecasting flood inflows is demonstrated through comparisons to traditional hydrological models and other machine learning networks, and our model consistently forecasts the peak time and total flood volume with the least amount of error in the comparison algorithm.

Quantitative Flood Damage Evaluation Using Grid-Based Spatial Analysis Data

In Korea, flood damage occurs every year due to typhoons and heavy rains, resulting in increasing damage to human lives and properties in urban areas. To reduce the scale of flood damage, economic analyses of flood-control work are conducted as part of efficient disaster management in the context of a limited budget. In this study, a quantitative evaluation of flood damage in Ulsan due to Typhoon Chaba was conducted using multi-dimensional flood damage analysis (MD-FDA). However, the land cover map applied to MD-FDA has limited data resolution and update intervals. Examination of domestic and foreign research cases to complement these spatial analysis data showed that grid data were being used in disaster-related fields. This study evaluated whether grid data are suitable for quantitative assessment through economic analyses conducted using new spatial analysis data such as road name address digital maps and 100 × 100 m grid-based spatial analysis data. The results of this study confirm that center-point-method grid data constitute spatial analysis data suitable for economic analysis.

Identification of the Key Influencing Factors of Urban Rail Transit Station Resilience against Disasters Caused by Rainstorms

Improving the ability of the urban rail transit system to cope with rainstorm disasters is of great significance to ensure the safe travel of residents. In this study, a model of the hierarchical relationship of the influencing factors is constructed from the resilience perspective, in order to research the action mechanisms of the influencing factors of urban rail transit stations susceptible to rainstorm disaster. Firstly, the concept of resilience and the three attributes (resistance, recovery, and adaptability) are interpreted. Based on the relevant literature, 20 influencing factors are discerned from the 3 attributes of the resilience of urban rail transit stations. Subsequently, an interpretative structural model (ISM) is utilised to analyse the hierarchical relationship among the influencing factors. The key influencing factors of station resilience are screened out using social network analysis (SNA). Combined with ISM and SNA for analysis, the result shows that the key influencing factors are: “Flood prevention monitoring capability”; “Water blocking capacity”; “Flood prevention capital investment”; “Personnel cooperation ability”; “Emergency plan for flood prevention”; “Flood prevention training and drill”; “Publicity and education of flood prevention knowledge”; and “Regional economic development level”. Therefore, according to the critical influencing factors and the action path of the resilience influencing factors, station managers can carry out corresponding flood control work, providing a reference for enhancing the resilience of urban rail transit stations.

Research and application of the mathematical model for extreme weather event in coastal urban areas

Extreme weather event simulation in coastal urban areas is more complex and difficult due to their special geography and climate characteristics, different kinds of land uses, close-packed buildings, and large amounts of flood control works and drainage systems. Urban Flood Simulation Model (UFSM) was integrated in this study to simulate the extreme weather events in the Pudong flood protection area (Shanghai, China). The model is established based on two-dimensional unsteady flow theory and nonstructural and irregular mesh technique. A method based on one-dimensional unsteady flow theory is proposed to deal with small-scale river and road. The calculation of the pumping stations, the water gates is indicated based on the real scheduling discipline. The extreme weather event scenarios (typhoon+rainstorm+ astronomical high tide + upstream flood) are simulated. The results show that the flood risk is higher in the coastal area and the upstream of the Huangpu Rive, and UFSM is a suitable method for simulating the flood inundation of coastal urban areas.

Calculation method of short-duration rainstorm intensity formula considering nonstationarity of rainfall series: impacts on the simulation of urban drainage system

AbstractThe changing nature of the Earth's climate and rapid urbanization lead to the change of rainfall characteristics in urban areas, the stability of rainfall series is destroyed and it is a difficult challenge to consider this change in urban drainage simulation. A generalized additive model (GAMLSS) with time as covariant was established to calculate and predict the design values of extreme rainstorm return period, and the nonstationary short-duration rainstorm intensity formula of three periods was fitted and compared with the stationary formula. The urban water simulation model and the MIKE 21 two-dimensional surface flow model are coupled to simulate the urban flood under different formulas and different return periods. The results show that the nonstationary results are worse in the same period. In the 5-year return period rainfall–runoff simulation performance, the nonstationary inundation area is 18.5% more than the stationary, and inundation water is 23.5% more than the stationary. The nonstationary simulation results show higher inundation depth and slower flood recession process. These gaps will widen in the future, but they will become less significant as the return period increases. It can provide a reference for the study of flood control work and the design of existing drainage infrastructure in the region.

Flood Control Capacity of the Three Gorges Project for Different Frequency Floods

An accurate assessment of flood control capacity of a reservoir is a prerequisite for ensuring the safety of flood control works. This study used the method of adding side reservoirs and used MIKE1...

Hydrological analysis of the September 2014 torrential floods of the Danube tributaries in the Eastern Serbia

Torrential flood as a rainfall precipitation driven natural hazard occurs in the watershed that responds within several hours due to a rugged topography. The extraordinary torrential flood event from September 15 2014 in the Eastern Serbia with its severe consequences, widespread material damages and casualties, draw an attention of the Serbian public and is a topic of this work. The combined method of Soil Conservation Service and synthetic unit triangular hydrograph is used to calculate the effective rainfall and peak discharges in five affected watersheds (Podvrska, Velika Kamenica, Slatinska, Zamna, and Mala Kamenica) in order to define the extremeness of this event. Special attention is given to the determination of the lag time defining the unit hydrograph and the curve numbers of the studied watersheds on the base of land use and hydrological class of soils with regard to geology, considering antecedent soil moisture conditions. Taking into account the high curve number (due to the high share of soils with an unfavorable hydrological conditions and high share of agriculture areas in land use), the shortest time to peak (due to the highest mean slope of river bed), the highest specific maximal discharge on subject date (4.58 m3s−1 km−2) as well as sediment transport data, the highest priority for erosion and torrential flood control works is attributed to the Mala Kamenica watershed. The results of this work may be a significant contribution to the flood risk assessment on a watershed level in this part of Eastern Serbia that should always start with reviewing and analyzing the historical torrential flood events.

Regional frequency analysis of annual daily rainfall maxima in Skåne, Sweden

AbstractExtreme daily rainfall events are critical for the urban drainage system, human life, agriculture and small catchments. The information about extreme rainfall magnitudes and frequencies is immensely important for civil engineers, city planners, scientists related to water management, rescue operations and flood control works. This study illustrates the results of regional frequency analysis (RFA) of annual maximum daily rainfall (AMDR) of Skåne County, Sweden. L‐moments based heterogeneity measure (H) reveals that the Skåne County is a homogeneous region. Based on the L‐moment ratio diagram and ZDist statistic results, the generalized normal (GNO) distribution is selected as the most suitable regional distribution. The accuracy measures used in K‐fold cross validation indicate that support vector machine (SVM) model is an appropriate model to find the index rainfall at ungauged sites in the region. The sites characteristics, elevation and latitude are identified as the most important variables to explain the variation in mean annual maximum daily rainfall (MAMDR). Finally, spatial maps of predicted MAMDR for different return periods are constructed by using index rainfall combined with regional quantiles. Spatial maps offer an overall view of the expected MAMDR in the region that is helpful for multiple decision makers including infrastructure planners, city planners, emergency managers, engineers and many others.

Study on annual rainfall forecast of Xishan station in Wenzhou City

Wenzhou city is Located in the southeast of Zhejiang Province, it belongs to subtropical climate. The main factors that affect the climate in Wenzhou include strong solar radiation and the regulation of marine water body. The annual variation of rainfall in Wenzhou City is very large. The disastrous weather in Wenzhou mainly includes typhoon, rain and drought. The ways of Typhoon Affecting Wenzhou include direct landing and adjacent area landing. Direct landing is more harmful. Rainfall is the most important factor affecting flood and drought disasters in Wenzhou City, so the analysis of rainfall can provide a reference for flood control and drought relief work in Wenzhou City. In this paper, BP neural network method is used to analyze and forecast the rainfall of Xishan station in the main urban area of Wenzhou City. The results show that the precipitation in Wenzhou City will change greatly in the next ten years. Flood disaster may occur in 2022 and 2028, and drought may occur in 2023.

Environmental Laws in Nigeria: Negligence and Compliance in the Building of Houses on Erosion and Flood Prone Areas in the South-South Region of Nigeria

This research work examined the assessment of Environmental Laws in Nigeria: Negligence and Compliance in the Building of Houses on Erosion and Flood Prone Areas in the South-South Region of Nigeria. Data for this study were collected from primary and secondary sources, through the administration of one thousand, seven hundred and twenty eight (1,728) copies of questionnaire using the random sampling method on respondents. Simple percentages, charts, student’s t-test, anova, and correlation statistical techniques were used in the analysis of the data collected. The results of the analysis revealed that 32.1% were in compliance; while 67.9% were non-compliance with environmental laws in the building of houses on erosion and flood prone areas in the South-South Region of Nigeria. The null hypothesis one was rejected in favour of the alternative hypothesis, which states that, there is a significant difference between the level of compliance in the building on erosion and flood prone areas within the study area. The study therefore recommends that, at present, all levels of Government should place more emphasis on the construction of flood and erosion control works, whenever there is flood and erosion menace. Although, the incorporation of the biological aspect with that of flooding and erosion control measures has proved to be somewhat effective, a more sustainable control of flooding and erosion problem should be advocated.

Design of Flood Control Hydrological Information Measurement and Forecast System in a Certain Area

In recent years, hydrological information in this area has played an important role in flood control and drought relief, and achieved good social, economic and ecological benefits, but there is still a certain gap with the latest requirements of the state in hydrological. With the rapid expansion of hydrological information collection stations and the rapid increase of station network density, considering the current needs of local hydrological information management, hydrological management departments and flood control and Drought Relief Command departments, this paper uses software engineering method to design a hydrological information measurement and reporting system. The system realizes centralized management of water information, real-time information query and analysis, dynamic monitoring and alarm, auxiliary decision-making, remote data collection and other hydrological business functions and provides decision support for leaders of all departments. It plays an important role in the success of flood control and drought relief work to minimize the loss of disasters and ensure the safety of people’s lives and properties with the least human and material resources.

Analysis of urban flood prevention emergency plan in Pinghu City

With the acceleration of urbanization in China, urban flood disasters have gradually become a prominent type of urban disease, seriously affected the normal production and life of urban residents, and brought great challenges to urban flood control and disaster reduction work. Based on the current situation of urban flood control in Pinghu City and the latest Guidelines for the Compilation of Urban Flood Control Emergency Preparedness Plan, this paper analyses the scope of application, key defense objects and key points of urban flood control in Pinghu City, and puts forward the organizational system and responsibilities of urban flood control, preventive and early warning measures, emergency response actions, public defense guidelines, personnel transfer and placement, etc. Specific non-engineering measures for urban flood control are put forward for Pinghu City.

Critical dependence of morphodynamic models of fluvial and tidal systems on empirical downslope sediment transport

The morphological development of fluvial and tidal systems is forecast more and more frequently by models in scientific and engineering studies for decision making regarding climate change mitigation, flood control, navigation and engineering works. However, many existing morphodynamic models predict unrealistically high channel incision, which is often dampened by increased gravity-driven sediment transport on side-slopes by up to two orders of magnitude too high. Here we show that such arbitrary calibrations dramatically bias sediment dynamics, channel patterns, and rate of morphological change. For five different models bracketing a range of scales and environments, we found that it is impossible to calibrate a model on both sediment transport magnitude and morphology. Consequently, present calibration practice may cause an order magnitude error in either morphology or morphological change. We show how model design can be optimized for different applications. We discuss the major implications for model interpretation and a critical knowledge gap.

Calculation of Early Warning Indicators for Small Watersheds Based on Mathematical Statistics

The early warning and forecasting of mountain flood disasters is an indispensable part of mountain flood prevention and control work. Reasonable selection of rainfall warning indicators is the key to mountain flood warning and forecasting work. This paper proposes a method for calculating the critical rainfall warning indicator based on mathematical statistics. That is, the characteristic period is determined based on the confluence time and watershed characteristics of the upstream watershed of the disaster prevention object. The stimulated rainfall of each characteristic period and its corresponding antecedent precipitation index is calculated based on the rainfall data of the flooding. Using the regression analysis method to draw the critical rainfall line, calculate the critical rainfall warning indicator and take the typical disaster prevention objects of Chahekou Village in Muping District of Yantai City, Shandong Province as an example, and the historical rainfall records of 2014-2018 were used as verification data to verify the early warning indicators. The results show that the critical rainfall accuracy calculated by this method is about 80%, which can provide reference for the application of early warning indicators for mountain flood disasters.