MIKE FLOOD Research Articles

Flood hazard assessment using machine learning and hydrodynamic modeling: case study in the Vu Ga–Thu Bon basin in Vietnam

ABSTRACT The objective of this study was the construction of a theoretical framework to evaluate flood hazards by integrating machine learning and hydrodynamic modeling in Vietnam's Vu Gia–Thu Bon basin. MIKE FLOOD was used to simulate historical floods in 2017 in order to obtain flood depth and velocity. Support vector machine-stochastic gradient descent (SVM-SGD), decision trees (DT), and dagging (DA) were used to determine flood susceptibility. Flood hazard was constructed by combining the flood depth, velocity, and susceptibility using the analytic hierarchy process technique. The statistical indices AUC, RMSE, MAE, and NASH were used to evaluate the precision of the hydrodynamic and machine learning models. The results showed that hydrodynamic modeling was highly accurate, with a NASH value of 0.86. The proposed models achieved AUC values of 0.98 for SVM-SGD, 0.93 for DT, and 0.92 for DA. The results showed that 7.59% of the flood zones is located in the very low flood hazard zone, 108.2 km2 in the low flood hazard zone, 24.59% in the moderate flood hazard zone, 22.53% in the high flood hazard zone, and 10.01% in the very high flood hazard zone.

Application of Numerical Modeling and GIS for Simulating Inundation Under Dam Failure Scenarios

Abstract Dam failure and unsafe dam reservoirs cause extremely serious flooding and affecting the environment and ecosystem in the downstream area. The study applied numerical modelling (MIKE 11, MIKE 21, MIKE FLOOD) combined with GIS technology to simulate flooding due to the collapse of Dong Be reservoir, Thanh Hoa, Vietnam, with flood scenarios of frequency P=1.5% and P=0.5%. The study calibrated and validated the MIKE FLOOD model for two historic flood events in 2010 and 2017. Assessment results show that they were relatively consistent with flood trace survey data. Inundation results in two scenarios show that the inundation area with the P=0.5% scenario tends to increase compared to the P=1.5% scenario. The evaluation of simulation results for flooding under two scenarios, when overlaid with administrative, population, and construction layers, will help assess the impact of dam failure and establish its consequences.

Flood modeling in the Ba River basin using a coupled hydrodynamic model—MIKE FLOOD

AbstractThe problem of flooding in Central Vietnam in general and the lower Ba River in particular is one of the natural disasters that frequently threatens people's lives and socioeconomic development in the region. Especially, climate change is becoming ever more prominent and hotter, making extreme natural disasters more unusual and unpredictable. In this research, MIKE‐FLOOD—a model that connects a 1‐dimensional (1‐D) MIKE 11 Hydrodynamics (HD) model with a 2‐dimensional (2‐D) MIKE 21 HD model—was used to set up. The model was calculated for three floods: (1) flood in October 1993, (2) flood in November 2003, and (3) flood in November 2007; these are floods with high frequency and relatively large magnitude. The results show that the 1993 flood rose and receded quickly. The flood peak inundated an area of 22,600 ha, accounting for 52% of the natural area. The flooded areas deeper than 1, 2, 3, 4, and 5 m were 16500, 11,000, 7000, 4200, and 2200 ha, respectively. In the center of Tuy Hoa city, the flooded area at the time of maximum water level was almost 100%.

Influence of rainfall pattern and infiltration capacity on the spatial and temporal inundation characteristics of urban waterlogging.

The rapid development of the city leads to the continuous updating of the land use allocation ratio, particularly during the flood season, which will exacerbate the significant changes in the spatial and temporal patterns of urban flooding, increasing the difficulty of urban flood forecasting and early warning. In this study, the spatial and temporal evolution of flooding in a high-density urban area was analyzed based on the Mike Flood model, and the influence mechanisms of different rainfall peak locations and infiltration rate scenarios on the spatial and temporal characteristics of urban waterlogging were explored. The results revealed that under the same return period, the larger the rainfall peak coefficient, the larger the peak value of inundation volume and inundation area. When the rainfall peak coefficient is small, the higher the return period is, and the larger the peak lag time of the inundation volume is, in which P = 50a, r = 0.2, the peak lag time of the inundation volume reached 32min and 45min for the inundation depths H > 0.03 m and H > 0.15 m, respectively. There are also significant differences in the peak lag time of waterlogging inundation volume for different inundation depths. The greater the inundation depth, the longer the peak lag time of the inundation volume, and the higher the return period, the more significant the effect of lag time prolongation. It is worth noting that the increase in infiltration rate may lead to an advance in the peak time of inundation volume and inundation area, and the peak time of the inundation area is overall more obvious than that of inundation volume. The effect of infiltration rate on the peak time of inundation volume for larger inundation depths was relatively large; the peak times of inundation volume and inundation area were advanced by 4-6 min and 4-8 min for H > 0.03 m and H > 0.15 m, respectively, after the increase in infiltration rate, and the higher the rainfall return period, the longer the advance time. The spatial and temporal characteristics of waterlogging under different peak rainfall locations and infiltration capacities obtained in this study can help provide a new perspective for temporal forecasting and warning of urban waterlogging.

Integration of machine learning and hydrodynamic modeling to solve the extrapolation problem in flood depth estimation

Abstract Flood prediction is an important task, which helps local decision-makers in taking effective measures to reduce damage to the people and economy. Currently, most studies use machine learning to predict flooding in a given region; however, the extrapolation problem is considered a major challenge when using these techniques and is rarely studied. Therefore, this study will focus on an approach to resolve the extrapolation problem in flood depth prediction by integrating machine learning (XGBoost, Extra-Trees (EXT), CatBoost (CB), and light gradient boost machines (LightGBM)) and hydraulic modeling under MIKE FLOOD. The results show that the hydraulic model worked well in providing the flood depth data needed to build the machine learning model. Among the four proposed machine learning models, XGBoost was found to be the best at solving the extrapolation problem in the estimation of flood depth, followed by EXT, CB, and LightGBM. Quang Binh province was hit by floods with depths ranging from 0 to 3.2 m. Areas with high flood depths are concentrated along and downstream of the two major rivers (Gianh and Nhat Le – Kien Giang).

Using a scenario-neutral approach to assess the impacts of climate change on flooding in the Ba River Basin, Viet Nam

Abstract Due to the hydrologic non-stationarity and uncertainty related to the probability assignment of flood peaks under climate change, the use of flood statistics may no longer be applicable. Therefore, a sensitivity analysis (i.e., a scenario-neutral approach) is used to examine the impacts of climate change on flooding in the Ba River Basin. A Delphi method with a set of KAMET rules was used to obtain a representative and a threshold flood event. These inputs are used for hydraulic simulation using a MIKE FLOOD model package. Flood simulations were performed using parametrically varied rainfall and temperature conditions. In total, 22 conditions were explored and are in line with CMIP5 and CMIP6. The results obtained have several implications. Firstly, rainfall change is the primary factor affecting flood impact in the Ba River Basin. Secondly, the flood peak in the Ba River Basin is highly sensitive to an increase in rainfall by up to 10%. Thirdly, the flooded threshold is reached when rainfall increases beyond 20%. Fourthly, the flood extent and depth are expected to increase as rainfall increases. Further research could improve the study using satellite rainfall data, satellite digital elevation models, and stochastic weather generators.

Urban inundation forecasting based on hydraulic models coupling MIKE Flood and MIKE Urban: A case study of Tam Ky City, Vietnam

AbstractUrban inundation has become a growing concern for many coastal cities around the world. Tam Ky City, located downstream of Ban Thach and Tam Ky rivers in central Vietnam, is no exception. According to annual statistics, the city frequently experiences heavy rainfall from tropical storms and monsoons, making inundation a recurring issue. In response to this challenge, this study developed a flood forecasting model specifically tailored for Tam Ky City, based on forecast rainfall and tidal levels. A key strength of the flood forecasting model lies in its integration of rainfall‐runoff processes, effectively connecting the river basin and the city. To ensure the model's accuracy and reliability, the parameters of the flood forecasting model were meticulously calibrated and verified for floods occurred on rivers as well as in urban areas. An experimental flood forecast was performed during Typhoon Nuru on September 28, 2022, and the forecast results of inundation locations and depths in the city well reflected the actual observations.

Flood risk mapping for the area with mixed floods and human impact: a case study of Yarkant River Basin in Xinjiang, China

Flooding has been causing severe consequences worldwide, including loss of human life and damage to property. Flood risk mapping, as a nonstructural measure, is efficient for flood protection and disaster alleviation. This study aims at completing the flood risk mapping of the region located at the middle reaches of the Yarkant River Oasis in western China, which has a dry climate and suffers from mixed flooding consisting of glacial outburst floods (GLOFs) and many other floods. In view of the complexity of flooding in the area, the study adopts two typical types of scenarios, namely overflow scenarios and dike-break scenarios, to complete the flood risk mapping. The MIKE FLOOD 1D/2D coupled model is used for two-dimensional flood flow simulation to compute the inundation depths and duration for flood risk assessment. The spatial overlay analysis was then used to combine the modeling results and land use/land cover layers with socioeconomic data to generate flood risk maps and damage losses under different scenarios. It is noted that evaporation and infiltration losses in the study area are not negligible because of the long flood process, the low precipitation, and dry surface/subsurface conditions. Due to the insufficient evaporation and infiltration data, a new method of synthesis loss rate is proposed to compute the evaporation/infiltration loss rate. Based on the water balance principle, the upstream and downstream flow data is utilized to calculate the water attenuation, which is then used to estimate the evaporation/infiltration loss rate. The proposed method can solve the problem of calculating evaporation/infiltration loss rates during the flooding process in such data-scarce areas. The flood risk mapping results indicate that the flood risk is high along the Yarkant River and that floods can cause severe inundation losses.

Apply MIKE models to study the impacts of climate change on flooding and design adaptation measures in Can Tho City in the Vietnamese Mekong Delta.

Can Tho City in the Mekong Delta usually has pluvial and fluvial floods every year. The situation will get worst in the future under climate change. This study aims (i) to apply the MIKE 11, MIKE 21, and MIKE FLOOD model to simulate the impact of climate change scenarios on flooding in Can Tho city (ii) to suggest climate change adaptation measures for sustainable social-economic activities of the city. We considered the combined effect of sea-level rise including RCP 2.6, RCP 4.5, and RCP 8.5, and changes in climate factor (i.e., precipitation) for the years 2025, 2030, and 2050. The results show that the flood model is appropriate to simulate the flood. The flooded areas of the city under the scenarios of RCP 2.6 and RCP 8.5 will be increased from 2025 to 2050, and RCP 4.5 will be increased progressively from the year 2025 to 2030 and reduced to 2050. In the scenario of RCP 8.5, the flooded area of the city will be gradually increased in 2025, 2030, and 2050 at 3,559 ha, 3,719 ha, and 4,476 ha, respectively. Fifteen adaptation measures to climate change from 2021 to 2050 are suggested.

Numerical Simulation of the Flood and Inundation Caused by Typhoon Noru Downstream from the Vu Gia-Thu Bon River Basin

Typhoon Noru (2022) was a historic storm that caused significant damage to the central region of Vietnam. Typhoon Noru has caused strong winds and torrential rainfall in Da Nang, Quang Nam, and Quang Ngai. Quang Nam Province saw many trees and power lines fall, and many areas were flooded. The Da Nang government has reported the typhoon toppled many trees, blew the rooftops of three houses, damaged the walls of several schools, and caused a power outage at some 3200 substations. It resulted in widespread flooding in coastal areas and downstream from the Vu Gia-Thu Bon River river basin. This study evaluates the impact of Typhoon Noru. The results show that: (1) The numerical simulation was applied to re-analyze the offshore meteorological field with the Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) model as an input for 2D wave propagation and hydraulic models; (2) The study couples the 1D and 2D models in MIKE FLOOD to simulate the flood and inundation caused by Typhoon Noru in the study area. The calibration and validation results of the 1D hydraulic model, the 2D wave propagation model, and the 2D hydrodynamic model were reasonably good, with a Nash coefficient ranging from 0.84 to 0.96 and a percent bias (BIAS) of −0.9% to 7.5%. The results of the simulation showed that the flood and inundation caused by Typhoon Noru resulted in significant damage in two districts: Thang Binh in Quang Nam province and Hoa Vang in Da Nang province. The practical significance of these results is that they provide valuable support for warning systems and troubleshooting efforts related to the impact of typhoons.

Compounding effects of urbanization, climate change and sea-level rise on monetary projections of flood damage

Climate change and urbanization play critical roles in compounding future flood risk due to their adverse impacts on the rainfall regime and sea level rise. Although past studies have predicted the spatiotemporal variations in flood risk, these have appreciable limitations, viz. (i) flood risk is predicted mainly by accounting for one driver at a time (either ocean flooding or fluvial flooding); and (ii) monetization of flood damage due to future flooding had not been investigated. However, multiple drivers could lead to flooding in coastal areas. This study presents an innovative approach for investigating the cumulative effects of urbanization, changes to the rainfall regime, and sea level rise on consequential flood damage in a coastal urban area. A comprehensive flood damage and hazard prediction model was developed by integrating 1D-2D aspects of MIKE FLOOD and GIS technology to assess the flood scenarios for 2040, 2070, and 2100 by investigating three predictor variables: urbanization, rainfall regime, and sea level rise. The factorial design approach was used to construct a total of 27 future flood scenarios. Time horizons of 30 years provided for effectively capturing climate change and its influence on the hydrologic regime. The Generalized Linear Model (GLM) was applied to create a statistical model based on future scenarios for each time horizon. Results confirmed that changes to the rainfall regime significantly influence the average annual damage (AAD) caused by flooding for all time horizons. At the same time, the significance of the effects of urbanization and sea level rise was found to vary. The model predicts that by 2040, urbanization would exacerbate AAD, with a significant contribution from sea level rise. In contrast, sea level rise would provide a marginally greater and more significant contribution to AAD compared to urbanization in 2040 and 2070. Compared to the base year 2017, AAD was 78%, 197%, and 351% higher in 2040, 2070, and 2100, respectively. The proposed flood damage prediction model developed can guide modelers and decision-makers in assessing the compounding flood damage for future flood management in any geographic location.

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.

Influence Of Flood Control Facilities On The Water Level In The Downstream Of The River System Sai Gon - Dong Nai

Ho Chi Minh City, Vietnam’s largest city, located on the lower reaches of the Sai Gon-Dong Nai (SG-DN) river system, is facing increasingly severe flooding due to changes in river flow and water levels. This article presents the results of a study to assess the impact of hydraulic structures located in the upper reaches on the water level in the lower reaches of the SG-DN River. As part of a study to assess the impact of upstream reservoirs and flood control structures on the water level in the lower reaches of the SG-DN River, hydrological data of the river network were collected and a hydraulic model was developed based on a digital elevation model (DEM) using the software package Mike 11, Mike 21 and Mike Flood. The water level of the Sai Gon River from the upper reaches to the Thu Dau Mot measuring station directly depends on the Dau Tieng reservoir, and the Tri An reservoir directly affects the water level in the river section from behind the Tri An dam to the Dong Nai section in the Tam An - Long Phuoc area. In the sections of the Sai Gon and Dong Nai rivers, which are less affected by the two overlying reservoirs, it is necessary to develop preventive measures to supply sufficient fresh water to meet the needs of the population and industries. In areas prone to flooding and underflooding as a result of the operation of anti-flood locks, it is also necessary to reconstruct hydraulic structures (raise the elevations of foundations, expand drainage systems, build reservoirs for collecting flood water etc.)

Influence of flood control facilities on water level in downstream of river system Sai Gon -Dong Nai

Ho Chi Minh City, Vietnam's largest city, located on the lower reaches of the Sai Gon-Dong Nai (SG-DN) river system, is facing increasingly severe flooding due to changes in river flow and water levels. This article presents the results of a study to assess the impact of hydraulic structures located in the upper reaches on the water level in the lower reaches of the SG-DN River. As part of a study to assess the impact of upstream reservoirs and flood control structures on the water level in the lower reaches of the SG-DN River, hydrological data of the river network were collected. A hydraulic model was developed based on a digital elevation model (DEM) using the software package Mike 11, Mike 21 and Mike Flood. The water level of the Sai Gon River from the upper reaches to the Thu Dau Mot measuring station depends on the Dau Tieng reservoir, and the Tri An reservoir directly affects the water level in the river section from behind the Tri An dam to the Dong Nai section in the Tam An - Long Phuoc area. In the sections of the Sai Gon and Dong Nai rivers, which are less affected by the two overlying reservoirs, it is necessary to develop preventive measures to supply sufficient fresh water to meet the population's and industries' needs. In areas prone to flooding and underflooding due to the operation of anti-flood locks, it is also necessary to reconstruct hydraulic structures (raise the elevations of foundations, expand drainage systems, build reservoirs for collecting flood water, etc.)

APPLICATION OF MIKE FLOOD MODEL FOR INUNDATION SIMULATION IN YEN BAI CITY

Flood is a natural disaster that can cause loss of life and damage to property. The objective of this study is to create a flood map of Yen Bai city, where flood occurs regularly during heavy rain and Thao River's water level rises. The study used Mike Flood model based on the connection of 1D and 2D hydrodynamic models. The model parameters were calibrated and validated againts observed water level data of two major flood events in August 2008 and July 2009 which were measured by Bao Ha and Yen Bai hydrological stations, in addition with historical flood survey data in 2008. Flood map was developed corresponding to the alarm levels. The results show that the most affected areas by flood are 4 communes of Au Lau, Hop Minh, Tuy Loc, and Hong Ha wards.

Urban flooding response to rainstorm scenarios under different return period types

• A new urban rainstorm pattern design method. • Realization of design value of characteristic rainstorm elements in multivariate environment. • The effects of various return period definitions on urban flooding results. Urban flooding research cannot be overemphasized due to its environmental, economic and societal concern. Research on the response of urban flooding under different rainstorm scenarios would be conducive to the design of drainage projects, and helps the government department to master the waterlogging process in advance. Thus, this paper introduces a new rainstorm pattern designing method using Copula theory, Most-Likely design realization method and Monte Carlo simulation based on the rainfall data in a Chinese megacity, Zhengzhou. Furthermore, a coupled one-dimensional and two-dimensional hydrodynamic model, MIKE FLOOD, was used to determine the urban flooding response to various rainstorm scenarios. The results show that more than 75 percent of waterlogging disasters in Zhengzhou city were caused by short duration rainstorms within 3 hours, and the one-hour single-peak rainstorm process plays a main role. The rainstorm volume (RV) under Kendall return period type decreased significantly compared with the radical “Or” return period. And the RV under survival Kendall return period type was improved compared to the conservative “And” return period. Moreover, the rainstorm scenario corresponding to “Or” return period brought about the most serious waterlogging disaster, with the peak inundation volume of 1.8 × 10 5 m³ and the maximum water depth of 1.86 m.

Identifying Modelling Issues through the Use of an Open Real-World Flood Dataset

The present work deals with the reconstruction of the flood wave that hit Mandra town (Athens, Greece) on 15 November 2017, using the framework of forensic hydrology. The flash flood event was caused by a huge storm event with a high level of spatial and temporal variability, which was part of the Medicane Numa-Zenon. The reconstruction included: (a) the post-event collection of 44 maximum water depth traces in the town; and (b) the hydrodynamic simulation employing the HEC-RAS and MIKE FLOOD software. The derived open dataset (which also includes additional data required for hydrodynamic modeling) is shared with the community for possible use as a benchmark case for flood model developers. With regards to the modeling issues, we investigate the calibration strategies in computationally demanding cases, and test whether the calibrated parameters can be blindly transferred to another simulator (informed modeling). Regarding the calibration, it seems that the coupling of an initial screening phase with a simple grid-search algorithm is efficient. On the other hand, the informed modeling concept does not work for our study area: every numerical model has its own dynamics while the parameters are of grey-box nature. As a result, the modeler should always be skeptical about their global use.

Habitat response of adult fish species under the influence of ecological flow and hydrodynamic regime in perennial river system

AbstractThe escalating anthropogenic activities in recent decades are constantly affecting the aquatic ecology and posing a threat to freshwater species. In this study, a two‐dimensional ecohydraulic model and multiple criteria decision analysis (MCDA) coupled framework is employed in the Dikhow River, India, to investigate the favourable habitat condition for the nearly threatened Notopterus chitala fish locally known as Chital fish. The habitat residence suitability and habitat suitability indices are calculated at the observed and ecological flows. The ecological flow rates are computed from flow duration curve shifting and flow duration curve analysis methods. The hydrodynamic computations are carried out using a 1D‐2D coupled MIKE FLOOD model. The habitat assessment of the targeted species is carried out by constructing the suitability curves from the computed hydraulic parameters at different environmental management conditions. Results from the habitat assessment curves indicate that the maximum habitat suitability index is found for the targeted fish species at average annual flow. Based on the MCDA analysis, the outer banks of the meander zones are identified as not suitable residence regions for the target species. This study revealed that the coupled approach could be useful to regulate the stream restoration strategies and identify potential habitat preference locations in the domain.

Comprehensive analysis of waterlogging control and carbon emission reduction for optimal LID layout: a case study in campus.

Nowadays, sponge city reconstruction has become the focus of research because of the increasingly serious urban waterlogging. Carbon emission reduction, waterlogging area reduction, cost, and other indicators were considered to explore the optimal sponge allocation scheme in the study area. The two-dimensional coupled model MIKE FLOOD was established to analyze the causes of waterlogging through numerical simulation. Low-impact development (LID) combination scenarios were set to analyze the control effects of waterlogging water and total runoff. The carbon emission reduction capacity and economic benefit of each scenario were calculated and evaluated. The analytic hierarchy process (AHP) was used to comprehensively evaluate the LID combination scenario and explore the optimal cost-benefit LID configuration scheme. The results show that the campus rainwater pipe network is under overload operation, and the number of overflow nodes accounts for up to 58.1% under the 3a rainfall return periods. After setting up LID measures, the runoff control rate can be increased by 26.15-42.84%, and the waterlogging area where the depth exceeds 15cm can be reduced by 72.87-100%. If the energy conservation and emission reduction benefits and costs are considered at the same time, the layout scenario of 9% bioretention facility + 3% green roof + 3% permeable pavement can achieve the best benefits. The research can provide a reference for planning and reconstruction of sponge campus and residential areas.

ASSESSMENT OF IMPACTS OF THE ROAD SYSTEM ON FLOOD REGIME IN THE COASTAL FLOODING AREA OF VU GIA - THU BAN RIVER BASIN, QUANG NAM PROVINCE

Flooding is one of the dangerous types of natural disasters, which has been causing great damage to human values and even human life, leading to negative impacts on socio-economic development, specifically in the lowland areas of the Vu Gia - Thu Bon river basin. The road system contributes to promoting intra-regional and inter-regional connectivity and is an important factor for socio-economic development. However, in certain cases, the road system continues to be expanded and enhanced, turning them into "dyke systems", interfering with the natural flood regime, increasing the area and flooding time. To assess the impact of the road system on the flood regime, the paper uses the Mike Flood modeling module to simulate the change of flood regime for flood events in 1999, 2007, 2020, and the 5% flood scenario. The comparison between the current road system and the old road system shows a certain increase in both depth and flooded area, especially in the case of 5% flood, the flood depth increases by 0.1 - 0.2 m in the upper part of the basin but only a small change in the lower part of the basin from 0.01 - 0.04 m.