Papers by Mathijs van Ledden
National-Level Multi-Hazard Risk Assessments in Sub-Saharan Africa
AGUFM, Dec 1, 2017
Urban Flood Risk Handbook: Assessing Risk and Identifying Interventions
Washington, DC: World Bank eBooks, Aug 2, 2023
This paper describes the development and application of a digital Hurricane Surge Atlas for New O... more This paper describes the development and application of a digital Hurricane Surge Atlas for New Orleans. This innovative tool is able to assess the surge threat of hurricanes in flood-prone delta areas in a few minutes during emergency situation with a high degree of reliability. This tool has been developed in the aftermath of Hurricane Katrina in 2005. A wide variety of storm scenarios from the numerical computations have been chosen as its basis. These results have been stored in a large GIS database and a visualization tool has been built to quickly extract storms from the database which resemble the forecasted storm. It turns out that the Hurricane Surge Atlas provides equal or even better results than the standard forecasting tool for surge levels provided that the hurricane has a reasonable match with the available scenarios in the Atlas. An important advantage of the Hurricane Atlas is that it enables the end-user a tool to quickly assess changes in weather forecasts (e.g. strengthening of the storm, or changes in storm track). It is recommended to further explore the performance of the Atlas for non-typical hurricanes and also integrate the information with levee characteristics to obtain direct insight into the performance of the flood risk reduction system.
IEEE Transactions on Automatic Control - IEEE TRANS AUTOMAT CONTR, 2003
Morphological modelling aims to explain and predict the changes in rivers, seas and estuaries due... more Morphological modelling aims to explain and predict the changes in rivers, seas and estuaries due to these interaction. In recent history, a lot of progress has been made, especially with stability analysis approaches. However, so far only the physical interactions have been taken into account. It is known however, that biological factors are important to the dynamics of the water systems. In this paper a first step is made in the inclusion of biology into the morphodynamic models. This inclusion is based on the effect that benthic organisms have on the erodibility of the bed. This can easily be included by a change of the critical bed shear stress. These changes in the critical bed shear stress then influence the morphology. This idea has been applied to two cases. The results of the first case indicate that this approach can reproduce the influence of benthic organisms on the mud content of the bed in estuaries. The second case shows that even low numbers of organisms can influenc...
Predicting of uncertainties in the morphological behaviour of a graded sediment river
Predicting the uncertainties of morphological effects due to river measures or changing natural c... more Predicting the uncertainties of morphological effects due to river measures or changing natural conditions is necessary for a sustainable development of these systems. Recently, various approaches have been presented to quantify these uncertainties (Van der Klis, 2003; Van Vuren 2005). They have showed that Monte Carlo simulations based on crude sampling (MCS) is a suitable method to quantify uncertainties in the results of morphological models. The MCS method is able to deal with the non-linear behaviour, the time and space dependence and the degree of uncertainty. Overall, these approaches were limited in that they only accounted for river systems with uniform sediment.
A Novel Technique for Rapid Flood Forecasting in Coastal Areas
Journal of waterway, port, coastal, and ocean engineering, Jul 1, 2013
The Lower Mississippi River protrudes into the Gulf of Mexico, and manmade levees line only the w... more The Lower Mississippi River protrudes into the Gulf of Mexico, and manmade levees line only the west bank for 55 km of the Lower Plaquemines section. Historically, sustained easterly winds from hurricanes have directed surge across Breton Sound, into the Mississippi River and against its west bank levee, allowing for surge to build and then propagate efficiently upriver and thus increase water levels past New Orleans. This case study applies a new and extensively validated basin-to channel-scale, high-resolution, unstructured-mesh ADvanced CIRCulation model to simulate a suite of historical and hypothetical storms under low to high river discharges. The results show that during hurricanes, (1) total water levels in the lower river south of Pointe à La Hache are only weakly dependent on river flow, and easterly wind-driven storm surge is generated on top of existing ambient strongly flow-dependent river stages, so the surge that propagates upriver reduces with increasing river flow; (2) natural levees and adjacent wetlands on the east and west banks in the Lower Plaquemines capture storm surge in the river, although not as effectively as the manmade levees on the west bank; and (3) the lowering of manmade levees along this Lower Plaquemines river section to their natural state, to allow storm surge to partially pass across the Mississippi River, will decrease storm surge upriver by 1 to 2 m between Pointe à La Hache and New Orleans, independent of river flow.
The objective of this paper is to describe the impact of climate change on the Mississippi River ... more 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.
An idealized meteorological-hydrdodynamic model for exploring extreme storm surge statistics in the North Sea in an alternative way
Have a water crisis? Time to call the Dutch
In het najaar van 2011 is Thailand zwaar getroffen door overstromingen, met meer dan 800 dodelijk... more In het najaar van 2011 is Thailand zwaar getroffen door overstromingen, met meer dan 800 dodelijke slachtoffers en ongeveer 45 miljard dollar directe schade. Nederlandse expertise werd ingeroepen voor het crisismanagement om de schade te beperken.
Modelling the influence of storm parameters on storm surges in New Orleans coastal basin
CRC Press eBooks, Nov 1, 2012
After the catastrophic flooding of New Orleans due to hurricane Katrina in the year 2005, the cit... more After the catastrophic flooding of New Orleans due to hurricane Katrina in the year 2005, the city's hurricane protection system has been improved to provide protection against storms with at least a 100 year return period. The aim of this article is to investigate the risk to life in the post-Katrina situation for the New Orleans metro bowl. In a risk-based approach the probabilities and consequences of various flood scenarios have been analyzed to estimate the risk to life. A two-dimensional hydrodynamic model has been used to simulate flood characteristics. Results indicate thatdepending on the flood scenariothe estimated loss of life in case of flooding ranges from about 100 to nearly 500. The highest life loss value is found for breaching of the river levees. Probability and consequence estimates are combined to evaluate the individual risk and societal risk for New Orleans. When compared to risks of other large scale engineering systems (e.g. other flood prone areas, dams and the nuclear sector) and acceptable risk criteria found in literature, the evaluated risk exceeds acceptable risk levels. Thus despite major improvements to the flood protection system, the flood risk of post-Katrina New Orleans is expected to be significant. Effects of risk reduction strategies on the risk level are investigated to assist in providing bases for decision making. Results indicate the necessity of further discussion regarding the management and reduction of the city's risk to flooding.
Journal of Flood Risk Management, Sep 1, 2009
After the catastrophic flooding of New Orleans due to hurricane Katrina plans are developed for t... more After the catastrophic flooding of New Orleans due to hurricane Katrina plans are developed for the improvement of the flood protection system of the city. In the article we apply the principles used in the Netherlands for risk based design of flood protection systems to the New Orleans metropolitan area. In this so-called economic optimization the incremental investments in more safety are balanced with the reduction of the risk to find an optimal level of flood protection. In the analysis a flood protection system has been assumed that consists of three different protected areas (or 'bowls'). Based on these layouts it has been investigated how different levels of flood protection affect the investment costs and the residual level of flood risk (= probability of flooding x consequences) and which economic optimum results from this analysis. Although the analyses are preliminary and not yet fully realistic the presented outcomes indicate that for densely populated areas, such as the central parts of New Orleans, it could be justified to choose a higher protection level than the currently proposed level of 1/100yr-1. The results of the economic optimization can be considered as technical advice that can be used as input for the (political) decision-making.
World Bank policy research working paper, Nov 29, 2022
The Policy Research Working Paper Series disseminates the findings of work in progress to encoura... more The Policy Research Working Paper Series disseminates the findings of work in progress to encourage the exchange of ideas about development issues. An objective of the series is to get the findings out quickly, even if the presentations are less than fully polished. The papers carry the names of the authors and should be cited accordingly. The findings, interpretations, and conclusions expressed in this paper are entirely those of the authors. They do not necessarily represent the views of the International Bank for Reconstruction and Development/World Bank and its affiliated organizations, or those of the Executive Directors of the World Bank or the governments they represent. This paper is a product of the Urban, Disaster Risk Management, Resilience and Land Global Practice. This research received financial support from the European Union (EU) in the framework of the EU-SAR Capacity Building for Disaster Risk Management Program, managed by the Global Facility for Disaster Reduction and Recovery (GFDRR). It is part of a larger effort by the World Bank to provide open access to its research and make a contribution to development policy discussions around the world.
Welfare and Climate Risks in Coastal Bangladesh: The Impacts of Climatic Extremes on Multidimensional Poverty and the Wider Benefits of Climate Adaptation
World Bank, Washington, DC eBooks, Mar 23, 2023
After the catastrophic flooding of New Orleans due to hurricane Katrina plans are developed for t... more After the catastrophic flooding of New Orleans due to hurricane Katrina plans are developed for the improvement of the flood protection system of the city. In the article we apply the principles used in the Netherlands for risk based design of flood protection systems to the New Orleans metropolitan area. In this so-called economic optimization the incremental investments in more safety are balanced with the reduction of the risk to find an optimal level of flood protection. In the analysis a flood protection system has been assumed that consists of three different protected areas (or 'bowls'). Based on these layouts it has been investigated how different levels of flood protection affect the investment costs and the residual level of flood risk (= probability of flooding x consequences) and which economic optimum results from this analysis. Although the analyses are preliminary and not yet fully realistic the presented outcomes indicate that for densely populated areas, such as the central parts of New Orleans, it could be justified to choose a higher protection level than the currently proposed level of 1/100yr-1. The results of the economic optimization can be considered as technical advice that can be used as input for the (political) decision-making.
Application of the Economic Optimization to the Flood Defence System of the New Orleans Metropolitan Area
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Papers by Mathijs van Ledden