scholarly journals Urbanization and climate change impacts on future urban flooding in Can Tho city, Vietnam

2013 ◽  
Vol 17 (1) ◽  
pp. 379-394 ◽  
Author(s):  
H. T. L. Huong ◽  
A. Pathirana

Abstract. Urban development increases flood risk in cities due to local changes in hydrological and hydrometeorological conditions that increase flood hazard, as well as to urban concentrations that increase the vulnerability. The relationship between the increasing urban runoff and flooding due to increased imperviousness is better perceived than that between the cyclic impact of urban growth and the urban rainfall via microclimatic changes. The large-scale, global impacts due to climate variability and change could compound these risks. We present the case of a typical third world city – Can Tho (the biggest city in Mekong River Delta, Vietnam) – faced with multiple future challenges, namely: (i) the likely effect of climate change-driven sea level rise, (ii) an expected increase of river runoff due to climate change as estimated by the Vietnamese government, (iii) increased urban runoff driven by imperviousness, and (iv) enhancement of extreme rainfall due to urban growth-driven, microclimatic change (urban heat islands). A set of model simulations were used to construct future scenarios, combining these influences. Urban growth of the city was projected up to year 2100 based on historical growth patterns, using a land use simulation model (Dinamica EGO). A dynamic limited-area atmospheric model (WRF), coupled with a detailed land surface model with vegetation parameterization (Noah LSM), was employed in controlled numerical experiments to estimate the anticipated changes in extreme rainfall patterns due to urban heat island effect. Finally, a 1-D/2-D coupled urban-drainage/flooding model (SWMM-Brezo) was used to simulate storm-sewer surcharge and surface inundation to establish the increase in the flood hazard resulting from the changes. The results show that under the combined scenario of significant change in river level (due to climate-driven sea level rise and increase of flow in the Mekong) and "business as usual" urbanization, the flooding of Can Tho could increase significantly. The worst case may occur if a sea level rise of 100 cm and the flow from upstream happen together with high-development scenarios. The relative contribution of causes of flooding are significantly different at various locations; therefore, detailed research on adaptation are necessary for future investments to be effective.

2011 ◽  
Vol 8 (6) ◽  
pp. 10781-10824 ◽  
Author(s):  
H. T. L. Huong ◽  
A. Pathirana

Abstract. Urban development increases flood risk in cities due to local changes in hydrological and hydrometeorological conditions that increase flood hazard, and also to urban concentrations that increase the vulnerability. The relationship between the increasing urban runoff and flooding due to increased imperviousness better perceived than that between the cyclic impact of urban growth and the urban rainfall via microclimatic changes. The large-scale, global impacts due to climate variability and change could compound these risks. We present the case of a typical third world city – Can Tho (the biggest city in Mekong River Delta, Vietnam) – faced with multiple future challenges, namely: (i) climate change-driven sea-level rise and tidal effect, (ii) increase river runoff due to climate change, (iii) increased urban runoff driven by imperviousness, and (iv) enhancement of extreme rainfall due to urban growth-driven micro-climatic change (urban heat islands). A set of model simulations were used to assess the future impact of the combination of these influences. Urban growth of the city was projected up to year 2100 based on historical growth patterns, using a land-use simulation model (Dinamica-EGO). A dynamic limited-area atmospheric model (WRF), coupled with a detailed land-surface model with vegetation parameterization (Noah LSM), was employed in controlled numerical experiments to estimate the anticipated changes in extreme rainfall patterns due to urban heat island effect. Finally, a 1-D/2-D coupled urban-drainage/flooding model (SWMM-Brezo) was used to simulate storm-sewer surcharge and surface inundation to establish the increase in the flood risk resulting from the changes. The results show that, if the city develops as predicted, the maximum of inundation depth and area in Can Tho will increase by about 20%. The impact of climate change on inundation is more serious than that of urbanization. The worse case may occur if the sea level rises 100 cm and the flow from upstream happen in the high-development scenarios. The relative contribution of causes of flooding are significantly different at various locations; therefore, detailed research on adaptation are necessary for the future investments to be effective.


2021 ◽  
Vol 8 ◽  
Author(s):  
Angel Amores ◽  
Marta Marcos ◽  
Rodrigo Pedreros ◽  
Gonéri Le Cozannet ◽  
Sophie Lecacheux ◽  
...  

The Maldives, with one of the lowest average land elevations above present-day mean sea level, is among the world regions that will be the most impacted by mean sea-level rise and marine extreme events induced by climate change. Yet, the lack of regional and local information on marine drivers is a major drawback that coastal decision-makers face to anticipate the impacts of climate change along the Maldivian coastlines. In this study we focus on wind-waves, the main driver of extremes causing coastal flooding in the region. We dynamically downscale large-scale fields from global wave models, providing a valuable source of climate information along the coastlines with spatial resolution down to 500 m. This dataset serves to characterise the wave climate around the Maldives, with applications in regional development and land reclamation, and is also an essential input for local flood hazard modelling. We illustrate this with a case study of HA Hoarafushi, an atoll island where local topo-bathymetry is available. This island is exposed to the highest incoming waves in the archipelago and recently saw development of an airport island on its reef via land reclamation. Regional waves are propagated toward the shoreline using a phase-resolving model and coastal inundation is simulated under different mean sea-level rise conditions of up to 1 m above present-day mean sea level. The results are represented as risk maps with different hazard levels gathering inundation depth and speed, providing a clear evidence of the impacts of the sea level rise combined with extreme wave events.


2013 ◽  
Vol 6 (2) ◽  
pp. 81-87 ◽  
Author(s):  
T. L. A. Driessen ◽  
M. van Ledden

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.


Eos ◽  
2017 ◽  
Author(s):  
Margaret Hurwitz ◽  
Felipe Mandarino ◽  
Dalia Kirschbaum

NASA-Rio-UCCRN Workshop on Sea Level Rise, Urban Heat Islands, and Water Quality; New York, 14–16 November 2016


2012 ◽  
Vol 5 (1) ◽  
pp. 333-349
Author(s):  
T. L. A. Driessen ◽  
M. van Ledden

Abstract. The objective of this paper is 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 improved model includes two important spillways that are operated during high flow conditions. Subsequently, a weighted multi-criteria calibration procedure was performed to calibrate the model for high flows. Validation for floods in 2011 indicates a very reasonable performance for high flows and clearly demonstrates the necessity of the spillways. 32 different scenarios are defined which includes the relatively large sea level rise and the changing discharge regime that is expected due to climate change. The impact of these scenarios is analysed by the hydrodynamic model. Results show 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. Potential alternatives on how to cope with the flood hazard of this river in the long term, such as river widening and large-scale redistribution of the flow through diversions, are proposed.


2017 ◽  
Vol 46 (3) ◽  
pp. 551-572
Author(s):  
Qi Lu ◽  
Justin Joyce ◽  
Sanaz Imen ◽  
Ni-Bin Chang

This study aims to conduct a multi-temporal change analysis of land use and land cover in New York City via a cellular automata-based Markov chain model that uses fuzzy set theory and multi-criteria evaluation to predict the city’s future land use changes for 2030 and 2050 under potential sea level rise and long-term rainfall-runoff flooding impacts driven by climate change. To determine the future natural forcing impacts on land use in New York City, this study highlights the need for integrating spatiotemporal modeling analyses, such as a statistical downscaling model driven by climate change with remote sensing and GIS to support urban growth assessment. The research findings indicate that the mean rainfall will increase in the future and sea levels will rise near New York City; however, open space is expected to decrease by 1.51% and 2.51% and the urban area is expected to expand by about 1.36% and 2.63% in 2030 and 2050 respectively, taking into account the climate change and sea level rise.


2020 ◽  
Author(s):  
Riccardo Giusti ◽  
Mario Martina ◽  
Clara Armaroli ◽  
Rui Figuereido ◽  
Francesco Dottori

<p>Climate change and subsidence will likely have a significant role to increase coastal flooding risk. The socio-economic impact of inundations can be very relevant, and, in a context of climate change, it is necessary to develop effective methods for assessing coastal flood hazard suitable for large-scale studies. This work focuses on the application of a new modelling approach for mapping flooding hazard for future scenarios characterized by sea level rise and ground lowering due to subsidence. The flood intensity index approach (Iw, Dottori et al. 2015) will be used to quantitatively evaluate the flood extent. This recent methodology allows to create reliable scenarios with low computational costs. The effects of the storm surge are assessed using a base scenario corresponding to 100 years return period event. IW inputs are represented by water height set as storm level plus a part of wave height. The scenarios will be created by quantitatively combining IPCC sea level rise projections with subsidence data that will be compared to high-resolution digital terrain models. The study area of this work is the ∼205 km long coastal plain of Northern Italy, from Venice to Rimini, composed of low-lying sandy beaches and which includes the Po delta area. The coast is characterized by large portions of the territory below mean sea level and by geological features made by recent quaternary sediments which have a natural subsidence rate. In the past (1960-1980) the subsidence rate had an exceptional increase caused by excessive groundwater withdrawal for agricultural and industrial activities, human consumption and by natural gas extraction.</p>


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