scholarly journals Has dyke development in the Vietnamese Mekong Delta shifted flood hazard downstream?

2017 ◽  
Vol 21 (8) ◽  
pp. 3991-4010 ◽  
Author(s):  
Nguyen Van Khanh Triet ◽  
Nguyen Viet Dung ◽  
Hideto Fujii ◽  
Matti Kummu ◽  
Bruno Merz ◽  
...  
Keyword(s):  
Flood Control ◽  
Flood Hazard ◽  
Mekong Delta ◽  
Hydraulic Model ◽  
Water Levels ◽  
Tidal Dynamics ◽  
Flood Peak ◽  
Disastrous Flood ◽  
The Impact ◽  
Flood Characteristics

Abstract. In the Vietnamese part of the Mekong Delta (VMD) the areas with three rice crops per year have been expanded rapidly during the last 15 years. Paddy-rice cultivation during the flood season has been made possible by implementing high-dyke flood defenses and flood control structures. However, there are widespread claims that the high-dyke system has increased water levels in downstream areas. Our study aims at resolving this issue by attributing observed changes in flood characteristics to high-dyke construction and other possible causes. Maximum water levels and duration above the flood alarm level are analysed for gradual trends and step changes at different discharge gauges. Strong and robust increasing trends of peak water levels and duration downstream of the high-dyke areas are found with a step change in 2000/2001, i.e. immediately after the disastrous flood which initiated the high-dyke development. These changes are in contrast to the negative trends detected at stations upstream of the high-dyke areas. This spatially different behaviour of changes in flood characteristics seems to support the public claims. To separate the impact of the high-dyke development from the impact of the other drivers – i.e. changes in the flood hydrograph entering the Mekong Delta, and changes in the tidal dynamics – hydraulic model simulations of the two recent large flood events in 2000 and 2011 are performed. The hydraulic model is run for a set of scenarios whereas the different drivers are interchanged. The simulations reveal that for the central VMD an increase of 9–13 cm in flood peak and 15 days in duration can be attributed to high-dyke development. However, for this area the tidal dynamics have an even larger effect in the range of 19–32 cm. However, the relative contributions of the three drivers of change vary in space across the delta. In summary, our study confirms the claims that the high-dyke development has raised the flood hazard downstream. However, it is not the only and not the most important driver of the observed changes. It has to be noted that changes in tidal levels caused by sea level rise in combination with the widely observed land subsidence and the temporal coincidence of high water levels and spring tides have even larger impacts. It is recommended to develop flood risk management strategies using the high-dyke areas as retention zones to mitigate the flood hazard downstream.

scholarly journals Has dyke development in the Vietnamese Mekong Delta shifted flood hazard downstream?

2017 ◽  
Author(s):  
Nguyen Van Khanh Triet ◽  
Nguyen Viet Dung ◽  
Hideto Fujii ◽  
Matti Kummu ◽  
Bruno Merz ◽  
...  
Keyword(s):  
Flood Control ◽  
Flood Hazard ◽  
Mekong Delta ◽  
Hydraulic Model ◽  
Water Levels ◽  
Tidal Dynamics ◽  
Flood Peak ◽  
Disastrous Flood ◽  
The Impact ◽  
Flood Characteristics

Abstract. In the Vietnamese part of the Mekong Delta (VMD) the areas with three rice crops per year have been expanded rapidly during the last 15 years. Paddy-rice cultivation during the flood season has been made possible by implementing high-dyke flood defenses and flood control structures. However, there are widespread claims that the high-dyke system has increased water levels in downstream areas. Our study aims at resolving this issue by attributing observed changes in flood characteristics to high-dyke construction and other possible causes. Maximum water levels and duration above the flood alarm level are analysed for gradual trends and step changes at different discharge gauges. Strong and robust increasing trends of peak water levels and duration downstream of the high-dyke areas are found with a step change in 2000/2001, i.e. immediately after the disastrous flood which initiated the high-dyke development. These changes are in contrast to the negative trends detected at stations upstream of the high-dyke areas. This spatially different behavior of changes in flood characteristics seems to support the public claims. To separate the impact of the high-dyke development from the impact of the other drivers, i.e. changes in the flood hydrograph entering the Mekong Delta, and changes in the tidal dynamics, hydraulic model simulations of the two recent large flood events in 2000 and 2011 are performed. The hydraulic model is run for a set of scenarios whereas the different drivers are interchanged. The simulations reveal that for the central VMD an increase of 9–13 cm in flood peak and 15 days in duration can be attributed to high-dyke development. However, for this area the tidal dynamics have an even larger effect in the range of 19–32 cm. However, the relative contributions of the three drivers of change vary in space across the delta. In summary, our study confirms the claims that the high-dyke development has raised the flood hazard downstream. However, it is not the only and not the most important driver of the observed changes. It has to be noted that changes in tidal levels caused by sea level rise in combination with the widely observed land subsidence and the temporal coincidence of high water levels and spring tides have even larger impacts. It is recommended to develop flood risk management strategies using the high-dyke areas as retention zones to mitigate the flood hazard downstream.

scholarly journals Comparison of Large Woody Debris Prototypes in a Large Scale Non-flume Physical Model

2018 ◽  
Vol 40 ◽  
pp. 05010
Author(s):  
Brian Perry ◽  
Colin Rennie ◽  
Andrew Cornett ◽  
Paul Knox
Keyword(s):  
Physical Model ◽  
Flood Control ◽  
Large Scale ◽  
Woody Debris ◽  
Water Levels ◽  
Mitigation Strategies ◽  
Large Woody Debris ◽  
Debris Accumulation ◽  
The Impact ◽  
The City

Due to excessive rainfall in June of 2013, several rivers located in and near the City of Calgary, Canada experienced significant flooding events. These events caused severe damage to infrastructure throughout the city, precipitating a renewed interest in flood control and mitigation strategies for the area. A major potential strategy involves partial diversion of Elbow River flood water to the proposed Springbank Off-Stream Storage Reservoir. A large scale physical model study was conducted to optimize and validate the design of a portion of the new project. The goals of the physical model were to investigate diversion system behaviors such as flow rates, water levels, sediment transport and, debris accumulation, and optimize the design of new flow control structures to be constructed on the Elbow River. In order to accurately represent the behavior of debris within the system due to flooding, large woody debris created from natural sources was utilized in the physical model and its performance was compared to that of debris of the same size fabricated from pressed cylindrical wood dowels. In addition to comparing the performance of these two debris types, the impact of root wads on debris damming was also investigated. Significant differences in damming behavior was shown to exist between the natural debris and the fabricated debris, while the impact of root wad on damming affected the dam structure and formation. The results of this experiment indicate that natural debris is preferred for studies involving debris accumulation.

scholarly journals Influence of Ciawi and Sukamahi dam construction on flood early warning system in Katulampa weir

2019 ◽  
Vol 276 ◽  
pp. 04016
Author(s):  
Maulana Asrafi ◽  
Evi Anggraheni ◽  
Dwita Sutjiningsih
Keyword(s):  
Early Warning ◽  
Early Warning System ◽  
Flood Control ◽  
Warning System ◽  
System Level ◽  
Dam Construction ◽  
Monitoring Point ◽  
Flood Peak ◽  
Flood Level ◽  
The Impact

Based on the Comprehensive Flood Management Plan (CFMP), one of the flood control alternatives in the Ciliwung Watershed is using the dry dam construction. Construction of Ciawi dam and Sukamahi dam who are located in Bogor District, are expected to decrease the flood peak and increasing the time concentration in order to reduce the impact caused by a flood in DKI Jakarta due to Ciliwung River. With the construction of Ciawi dam and Sukamahi dam, it is necessary to conduct a research on the effect of both dams construction in Katulampa Weir, one of monitoring point dams on the DKI Jakarta Flood Early Warning System. Hydrological analysis with Win-TR 20 and HEC-RAS was conducted to identify the changes in the flood level of Flood Early Warning System in DKI Jakarta with and without both dams are available. The results of this study indicate that the peak floods decreased by around 2.5% after the implementation of Ciawi dam and Sukamahi dams. The impacts of this reduction will not affect the Flood Early Warning System level at Katulampa Weir significantly.

scholarly journals Flooding in the Mekong Delta: the impact of dyke systems on downstream hydrodynamics

2020 ◽  
Vol 24 (1) ◽  
pp. 189-212 ◽  
Author(s):  
Vo Quoc Thanh ◽  
Dano Roelvink ◽  
Mick van der Wegen ◽  
Johan Reyns ◽  
Herman Kernkamp ◽  
...  
Keyword(s):  
Mekong Delta ◽  
High Flow ◽  
Water Levels ◽  
Mekong River ◽  
Low Flow ◽  
Water Level Fluctuations ◽  
Tidal Propagation ◽  
Extreme Flood ◽  
Year 2000 ◽  
The Impact

Abstract. Building high dykes is a common measure of coping with floods and plays an important role in agricultural management in the Vietnamese Mekong Delta. However, the construction of high dykes causes considerable changes in hydrodynamics of the Mekong River. This paper aims to assess the impact of the high-dyke system on water level fluctuations and tidal propagation in the Mekong River branches. We developed a coupled 1-D to 2-D unstructured grid using Delft3D Flexible Mesh software. The model domain covered the Mekong Delta extending to the East (South China Sea) and West (Gulf of Thailand) seas, while the scenarios included the presence of high dykes in the Long Xuyen Quadrangle (LXQ), the Plain of Reeds (PoR) and the Trans-Bassac regions. The model was calibrated for the year 2000 high-flow season. Results show that the inclusion of high dykes changes the percentages of seaward outflow through the different Mekong branches and slightly redistributes flow over the low-flow and high-flow seasons. The LXQ and PoR high dykes result in an increase in the daily mean water levels and a decrease in the tidal amplitudes in their adjacent river branches. Moreover, the different high-dyke systems not only have an influence on the hydrodynamics in their own branch, but also influence other branches due to the Vam Nao connecting channel. These conclusions also hold for the extreme flood scenarios of 1981 and 1991 that had larger peak flows but smaller flood volumes. Peak flood water levels in the Mekong Delta in 1981 and 1991 are comparable to the 2000 flood as peak floods decrease and elongate due to upstream flooding in Cambodia. Future studies will focus on sediment pathways and distribution as well as climate change impact assessment.

scholarly journals Hydrometeorological drivers of flood characteristics in the Brahmaputra river basin in Bangladesh

2021 ◽  
Author(s):  
Sazzad Hossain ◽  
Hannah L. Cloke ◽  
Andrea Ficchì ◽  
Andrew G. Turner ◽  
Elisabeth M. Stephens
Keyword(s):  
Water Level ◽  
Morphological Changes ◽  
High Water ◽  
Water Levels ◽  
Future Climate Change ◽  
South Asian Summer Monsoon ◽  
Large Variability ◽  
Long Duration ◽  
The Impact ◽  
Flood Characteristics

Abstract. While flooding is an annual occurrence in the Brahmaputra basin during the South Asian summer monsoon, there is large variability in the flood characteristics that drive risk: flood duration, rate of water level rise and peak water level. The aim of this study is to understand the key hydrometeorological drivers influencing these flood characteristics. We analyse hydrometeorological time series of the last 33 years to understand flood dynamics focusing on three extraordinary floods in 1998 (long duration), 2017 (rapid rise) and 2019 (high water level). We find that long duration floods in the basin have been driven by basin-wide seasonal rainfall extremes associated with the development phase of strong La Niña events, whereas floods with a rapid rate of rise have been driven by more localized rainfall falling in a hydrological ‘sweet spot’ that leads to a concurrent contribution from the tributaries into the main stem of the river. We find that recent record high water levels are not coincident with extreme river flows, hinting that sedimentation and morphological changes are also important drivers of flood risk that should be further investigated. Understanding these drivers is essential for flood forecasting and early warning and also to study the impact of future climate change on flood.

scholarly journals The large-scale impact of climate change to Mississippi flood hazard in New Orleans

2013 ◽  
Vol 6 (2) ◽  
pp. 81-87 ◽  
Author(s):  
T. L. A. Driessen ◽  
M. van Ledden
Keyword(s):  
Climate Change ◽  
Sea Level Rise ◽  
New Orleans ◽  
Sea Level ◽  
Mississippi River ◽  
Flood Hazard ◽  
Water Levels ◽  
Impact Of Climate Change ◽  
High Flows ◽  
The Impact

Abstract. The objective of this paper was to describe the impact of climate change on the Mississippi River flood hazard in the New Orleans area. This city has a unique flood risk management challenge, heavily influenced by climate change, since it faces flood hazards from multiple geographical locations (e.g. Lake Pontchartrain and Mississippi River) and multiple sources (hurricane, river, rainfall). Also the low elevation and significant subsidence rate of the Greater New Orleans area poses a high risk and challenges the water management of this urban area. Its vulnerability to flooding became dramatically apparent during Hurricane Katrina in 2005 with huge economic losses and a large number of casualties. A SOBEK Rural 1DFLOW model was set up to simulate the general hydrodynamics. This model included the two important spillways that are operated during high flow conditions. A weighted multi-criteria calibration procedure was performed to calibrate the model for high flows. Validation for floods in 2011 indicated a reasonable performance for high flows and clearly demonstrated the influence of the spillways. 32 different scenarios were defined which included the relatively large sea level rise and the changing discharge regime that is expected due to climate change. The impact of these scenarios on the water levels near New Orleans were analysed by the hydrodynamic model. Results showed that during high flows New Orleans will not be affected by varying discharge regimes, since the presence of the spillways ensures a constant discharge through the city. In contrary, sea level rise is expected to push water levels upwards. The effect of sea level rise will be noticeable even more than 470 km upstream. Climate change impacts necessitate a more frequent use of the spillways and opening strategies that are based on stages.

scholarly journals Evaluation Study of Kedunglarangan River To Protect Flood In Pasuruan and Sidoarjo

2019 ◽  
Vol 1 (1) ◽  
pp. 55-62
Author(s):  
Ni Nyoman Adum M
Keyword(s):  
Flood Control ◽  
River Flow ◽  
Water Reservoir ◽  
Evaluation Study ◽  
Water Levels ◽  
Work Study ◽  
Flood Prevention ◽  
River Flood ◽  
Excavation Work ◽  
The Impact

Construction of the Kedunglarangan river flood control system designed to prevent flooding every rainy season in the Bangil sub-district. Kedunglarangan River is a river that flows in two regencies Sidoarjo and Pasuruan which has an area of 282.67 km2 watershed with a river length of 23.7 km. Kedunglarangan river has 4 (four) watershed sub-systems. The scope of this flood prevention work-study is the normalization of the Kedunglarangan River starting from the meeting with the Wrati River downstream up to 7 km. Normalization work is carried out with excavation and river widening to meet flood discharge in accordance with the conditions of the study area. If the river excavation work is done in accordance with the design master will form a basin that causes the creation of a dike. In this condition, it will be a temporary water reservoir where the water velocity is very low. So the work carried out the impact is only temporary. From the results of analysts, it is more efficient to do river widening and embankment raising rather than increasing river depth. River excavation work like that is very risky to create very fast sedimentation. Normalization method with river widening is one way to maintain the river flow downstream and flood water levels

scholarly journals Hydraulic Efficiency of Green-Blue Flood Control Scenarios for Vegetated Rivers: 1D and 2D Unsteady Simulations

Water ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 2620
Author(s):  
Giuseppe Francesco Cesare Lama ◽  
Matteo Rillo Migliorini Giovannini ◽  
Alessandro Errico ◽  
Sajjad Mirzaei ◽  
Roberta Padulano ◽  
...  
Keyword(s):  
Best Management Practices ◽  
Urban Areas ◽  
Flood Control ◽  
Management Practices ◽  
Flood Hazard ◽  
Control Area ◽  
Flood Hazards ◽  
Hydraulic Efficiency ◽  
Peak Reduction ◽  
The Impact

Flood hazard mitigation in urban areas crossed by vegetated flows can be achieved through two distinct approaches, based on structural and eco-friendly solutions, referred to as grey and green–blue engineering scenarios, respectively; this one is often based on best management practices (BMP) and low-impact developments (LID). In this study, the hydraulic efficiency of two green–blue scenarios in reducing flood hazards of an urban area crossed by a vegetated river located in Central Tuscany (Italy), named Morra Creek, were evaluated for a return period of 200 years, by analyzing the flooding outcomes of 1D and 2D unsteady hydraulic simulations. In the first scenario, the impact of a diffuse effect of flood peak reduction along Morra Creek was assessed by considering an overall real-scale growth of common reed beds. In the second scenario, riverine vegetation along Morra Creek was preserved, while flood hazard was mitigated using a single vegetated flood control area. This study demonstrates well the benefits of employing green–blue solutions for reducing flood hazards in vegetated rivers intersecting agro-forestry and urban areas while preserving their riverine ecosystems. It emerged that the first scenario is a valuable alternative to the more impacting second scenario, given the presence of flood control areas.

The Effect of a Disastrous Flood on the Quality of Life in Dongting Lake Area in China

2004 ◽  
Vol 16 (2) ◽  
pp. 126-132 ◽  
Author(s):  
H.Z. Tan ◽  
Y.J. Luo ◽  
S.W. Wen ◽  
A.Z. Liu ◽  
S.Q. Li ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Social Support ◽  
Flood Control ◽  
Negative Impact ◽  
Control Group ◽  
Lake Area ◽  
Disastrous Flood ◽  
Social Support Scale ◽  
The Impact

We carried out an epidemiological study to assess the impact of flood on the quality of life (QOL) of residents in the affected areas in China. We used a natural experiment approach, randomly selected 494 adults from 18 villages, which suffered from flooding as a result of embankments collapsing, 473 adults from 16 villages, which suffered from, soaked flood, and 773 adults from 11 villages without flood (control group). We used the Generic QOL Inventory-74 (GQOLI-74), social support scale, and questionnaires to assess the QOL of all study participants. The QOL was significantly poorer in soaked group (58.4) and (especially) in collapsed group (55.1) than in control group (59.5, p<0.001). Adjustment for potential confounding factors did not change the results. The impact of flood on QOL was stronger among farmers, seniors, persons with introvert personality, and residents with adverse life-events, whereas social support and extrovert personalities offset the negative impact of flood on QOL. Asia Pac J Public Health2004'; 16(2): 126-132.

scholarly journals Towards automatic calibration of 2-D flood propagation models

2010 ◽  
Vol 14 (6) ◽  
pp. 911-924 ◽  
Author(s):  
P. Fabio ◽  
G. T. Aronica ◽  
H. Apel
Keyword(s):  
Model Calibration ◽  
Degrees Of Freedom ◽  
Flood Control ◽  
Flood Hazard ◽  
Element Model ◽  
Water Levels ◽  
Control Measures ◽  
Automatic Calibration ◽  
Calibration Data ◽  
Model Setup

Abstract. Hydraulic models for flood propagation description are an essential tool in many fields and are used, for example, for flood hazard and risk assessments, evaluation of flood control measures, etc. Nowadays there are many models of different complexity regarding the mathematical foundation and spatial dimensions available, and most of them are comparatively easy to operate due to sophisticated tools for model setup and control. However, the calibration of these models is still underdeveloped in contrast to other models like e.g. hydrological models or models used in ecosystem analysis. This has two primary reasons: first, lack of relevant data against which the models can be calibrated, because flood events are very rarely monitored due to the disturbances inflicted by them and the lack of appropriate measuring equipment in place. Second, 2-D models are computationally very demanding and therefore the use of available sophisticated automatic calibration procedures is restricted in many cases. This study takes a well documented flood event in August 2002 at the Mulde River in Germany as an example and investigates the most appropriate calibration strategy for a simplified 2-D hyperbolic finite element model. The model independent optimiser PEST, that enables automatic calibrations without changing model code, is used and the model is calibrated against over 380 surveyed maximum water levels. The application of the parallel version of the optimiser showed that (a) it is possible to use automatic calibration in combination of 2-D hydraulic model, and (b) equifinality of model parameterisation can also be caused by a too large number of degrees of freedom in the calibration data in contrast to a too simple model setup. In order to improve model calibration and reduce equifinality, a method was developed to identify calibration data, resp. model setup with likely errors that obstruct model calibration.

Sign in / Sign up

Export Citation Format

Share Document