Flood Resilience of Private Properties

Thomas Hartmann, Willemijn van Doorn-Hoekveld, Helena F.M.W. van Rijswick, Tejo Spit, Thomas Hartmann, Willemijn van Doorn-Hoekveld, Helena F.M.W. van Rijswick, Tejo Spit

• Verlag: Routledge
• Jahr: 2020
• ISBN:
  9781000227543
• Auflage: 1
• Thema: Sciences biologiques
• Thema: Écologie

Flood Resilience of Private Properties examines the division and balance of responsibilities between the public and the private when discussing flood resilience of private properties.

Flooding is an expensive climate-related disaster and a threat to urban life. Continuing development in flood-prone zones compound the risks. Protecting all properties to the same standards is ever more challenging. Research has focused on improved planning and adapting publicly-owned infrastructure such as streets, evacuation routes, and retention ponds. However, damages often happen on private land. To realize a flood-resilient city, owners of privately-owned residential houses also need to act. Measures such as mobile barriers and backwater valves or avoiding vulnerable uses in basements can make homes more flood-resilient. But private owners may be unaware of flooding risks or may lack the means and knowledge to act. Incentives may be insufficient, while fragmented or unclear property rights and responsibilities entrench inertia. The challenge is motivating homeowners to take steps. Political and societal systems influence the action citizens are prepared to take and what they expect their governments to do. The responsibility for implementing such measures is shared between the public and the private domain in different degrees in different countries.

This book will be of great interest to scholars of water law, property rights, flood risk management and climate adaptation. This book was originally published as a special issue of Water International.

The levee effect along the Jamuna River in Bangladesh

Md Ruknul Ferdous, Anna Wesselink, Luigia Brandimarte, Giuliano Di Baldassarre and Md Mizanur Rahman

ABSTRACT

The levee effect refers to the paradox that the construction of a levee to protect from flooding might induce property owners to invest more in their property, increasing the potential damages should the levee breach. Thus, paradoxically, the levee might increase flood risk. The levee effect was observed for high-income countries. We analyze whether it can also be observed in a low-income country, Bangladesh. In the Jamuna floodplain different levels of flood protection have existed alongside each other since the 1960s, so their effects can be compared.

Introduction

In 1945, Gilbert F. White wrote that ‘floods are acts of God, but flood losses are largely acts of man. Human encroachment upon the floodplains of river accounts for the high annual toll of flood losses’ (White, 1945, p. 2). Following this observation, White postulated the existence of a ‘levee effect’ in flood risk management and presented evidence for this effect in the United States. ‘Levee’ is a universal term for embankments (man-made or natural) that prevent floodwater flowing from a river to the surrounding areas; dikes are the man-made levees. In this article we will use ‘levee’, since White’s hypothesis and subsequent research used this term. The levee effect is when the construction of levees to protect property from flooding induces property owners to invest more in their property, multiplying the risk should the levee breach or be overtopped. Of course, investment in property or economic capital may be exactly why the levee was constructed in the first place. With risk being defined as the product of the probability of events (here: flooding) occurring and the likelihood caused by damage of such events (Di Baldassarre, Castellarin, Montanari, & Brath, 2009; van Manen & Brinkhuis, 2005), the levee effect implies the paradoxical result that the construction of a levee can increase rather than reduce risk: while the frequency of flooding is reduced, the potential damage is magnified. Whether the risk indeed increases when a levee is constructed depends on the relative magnitude of the two factors, which will be different in different places and at different times (Tanoue, Hirabayashi, & Ikeuchi, 2016).

To reduce these risks, societies typically construct stronger levees, which again potentially increases the risk, and so on. The result is a lock-in of inescapable dependence on levees and ever-increasing expenditure for flood defence, with levees a condition for any inhabitation (Di Baldassarre et al., 2018; Logan, Guikema, & Bricker, 2018). This situation is perfectly illustrated by the Netherlands (Wesselink, 2007; Wesselink, Bijker, de Vriend, & Krol, 2007). The awareness of this lock-in has resulted in policy recommendations to ‘go soft’ in flood risk management, i.e., to focus on prevention, preparedness, emergency response and recovery after flooding, as for example in the EU Floods Directive (Gralepois et al., 2016; Hegger et al., 2016; Kreibich et al., 2017; Wesselink et al., 2015). Such ‘soft’ measures are believed to prioritize natural capital, community control, simplicity and appropriateness, while ‘hard’ engineering such as levees, groynes and revetments are capital-intensive, large, complex (and hence out of community control) and inflexible (Sovacool, 2011). This development to include more soft measures is a diversification that is needed in flood risk management; both hard and soft measures are needed for resilience to flooding. Therefore, trade-offs between the advantages and disadvantages of hard and soft measures should be considered carefully, as we will discuss in the concluding section.

Many studies have investigated the levee effect. Our literature survey yielded two types of study (see the following section). Most are single case studies to empirically test White’s hypothesis in high-income countries, using historical records to show trends. A few conceptual studies use agent-based models or dynamic systems models where case study data illustrate simplified hypothetical situations. We found no research that compares adjacent areas at the same time, where social and physical characteristics are similar but flood protection levels differ substantially. Our unique case study, the floodplain along the Brahmaputra/Jamuna River (Bangladesh), enables just this. This floodplain presents different flood protection measures on the two river banks. The Brahmaputra Right Embankment (BRE), a man-made earthen levee, was built in the 1960s parallel to the right bank (BWDB, 1992), but no similar structural investment was made on the left bank, leaving it unprotected. Furthermore, at the present time the BRE shows different characteristics along its length, with stronger levees (reinforced with concrete, and maintained) in the southern part of the right bank, and weaker (unmaintained) levees in the northern part. These differences enable us to compare the effect of different protection levels within an otherwise homogeneous region. Also, our case offers a unique opportunity to test the levee effect in a low-income country.

After reviewing the past studies on levee effects, we present our study area and research approach, and then present and discuss the research findings. We conclude with a few thoughts on policy implications.

Literature review: the levee effect

White’s (1945) publication has shaped the way flooding is perceived and revolutionized the methods by which risk and hazards are conceptualized more generally (Macdonald, Chester, Sangster, Todd, & Hooke, 2011). Indeed, White’s thesis has inspired several studies in which the levee effect was investigated. Below, we briefly review this literature. To focus our review, we selected publications in Web of Knowledge where explicit reference is made to the levee effect in the title or topic, or White (1945) is cited. The themes covered are: investment or land use (i.e., economic development), risk perception, hydraulic conditions, potential damage or vulnerability, and finally risks. The term ‘vulnerability’ is often used in these studies, but not always defined explicitly. It often denotes ‘expected damage’, while in risk research vulnerability is more formally defined as the product of exposure and hazard (Mechler & Bouwer, 2015), where

• exposure is the economic capital that is potentially affected by hazardous events, and

• hazard is the likelihood and severity of events.

However, other authors define vulnerability as the ‘likelihood of damage (including death or other undesirable consequences)’ (Reilly, Guikema, Zhu, & Igusa, 2017), which includes both exposure and vulnerability as defined e.g., by Mechler and Bouwer (2015). We will adopt the definition, where exposure is included in vulnerability, since this is how it is interpreted in most of the literature we discuss below, if often implicitly. Understanding of vulnerability in the socio-ecological systems and development studies literature is different again, with vulnerability closely related to measures of resistance and resilience, besides exposure (Adger, 2006; Gallopin, 2006; Pelling, 2003).

In studies on the levee effect, economic development is most often studied. Burton, Kates, and White (1968) undertook research on human adjustments to natural hazards on the floodplains of the Mississippi River and the Rio Grande. They observed that farmers in protected areas were cultivating more valuable crops than those in unprotected areas. Shin, Hong, Kim, and Kim (2014) describe how inhabitants’ behaviour changed after levee construction along three reaches of the Mankyung River, in South Korea. Levee construction led to a decrease of fallow land and an increase of urban and farmed land, which increases value and productivity. Eakin and Appendini (2008) also illustrate how the construction of levees in the Lerma Valley in Mexico rasied agricultural productivity and the economic value of farmland, but also increased vulnerability to flooding.

Turning to urban and industrial development, Domeneghetti, Carisi, Castellarin, and Brath (2015) examined economic and population dynamics in the Po floodplain in Italy, finding that industrial investment expanded over the last century, particularly in floodplains protected by levees, but their analysis was not conclusive as to a causal relationship between the two. Collenteur, de Moel, Jongman, and Di Baldassarre (2015) came to a similar conclusion in their study of the impact of flood disasters on the spatial population dynamics in floodplain areas of the Mississippi River in the US. They found a positive correlation between the frequency of flood damage and population growth, but they could not show causality. In their historical study of flood risk management in New Orleans, Kates, Colten, Laska, and Leatherman (2006) showed that the construction of levees induced additional development in the city, but also produced the lock-in described above. Montz and Tobin (2008) similarly found that the construction of levees in Yuba County, California, promoted floodplain development, even though protection could not be guaranteed due to poor maintenance.

In the reviewed papers, the inhabitants’ perception of flood risk (rather than the calculated flood risk) is usually seen as the intermediate step between the construction of levees and increased economic development and/or investment. Eakin and Appendini (2008) found that the presence of levees reduced farmers’ perception of flood risk and led to increased investment. Ludy and Kondolf (2012) found that people in California believed that flood risk was completely eliminated by levees, though they are effective only against floods with a return period shorter than 100 years. This sense of safety fostered intense urbanization of flood-prone areas. Fox-Rogers, Devitt, O’Neill, Brereton, and Clinch (2016) studied how flood risk preparedness might be increased in the coastal and riverside town of Bray, in County Wicklow, Ireland. They found that the levee effect could occur even before levees are fully constructed, as the people living in the area felt that flood threat was being reduced. This in turn diminished flood preparedness. Burton and Cutter (2008) examined an additional social factor that increases potential damage: the composition of the population in areas at risk from flooding due to levee failures in the Sacramento–San Joaquin Delta in California. They found that as cities expand and density of people and infrastru...

Inhaltsverzeichnis

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Citation Information
• Notes on Contributors
• Introduction: Increasing flood risk asks for new approaches
• 1 The levee effect along the Jamuna River in Bangladesh
• 2 Managing flood risk in shrinking cities: dilemmas for urban development from the Central European perspective
• 3 The effects of tailor-made flood risk advice for homeowners in Flanders, Belgium
• 4 More than a one-size-fits-all approach – tailoring flood risk communication to plural residents’ perspectives
• 5 Deconstructing the legal framework for flood protection in Austria: individual and state responsibilities from a planning perspective
• 6 Too much water, not enough water: planning and property rights considerations for linking flood management and groundwater recharge
• 7 Dealing with distributional effects of flood risk management in China: compensation mechanisms in flood retention areas
• 8 Sticks and carrots for reducing property-level risks from floods: an EU–US comparative perspective
• Index