Using Dutch coastal management for
protection against the effects of climate
change in Tampa Bay, FL, USA
AUTHORS
Sophie Baartman (10374388)
Lisa Bibbe (10432981)
Dorien van Kranenburg (10381007)
Bram Vonsée (10210660)
EXPERT: DHR. DR. K.F. RIJSDIJK TUTOR: MW. DR. M.F. HAMERS
2 TABLE OF CONTENTS Abstract ... 3 Introduction ... 4 Theoretical framework ... 6 Climate change ... 6 Resilience ... 7 Sustainability ... 8
Collective Action Theory ... 9
Research Methods ... 10
Results ... 11
Tampa Bay versus south-west netherlands ... 11
Coastal protection in south-west Netherlands ... 11
Tampa and Tampa Bay ... 12
New Orleans example ... 15
Resilience ... 16
Modelling storm surges ... 16
Oosterschelde versus Tampa Bay ... 18
Conclusion and discussion ... 20
Recommendations ... 21 References ... 22 Appendixes ... 26 Appendix I ... 26 MATLAB script ... 26 Appendix II ... 30
3
ABSTRACT
In this paper, a possible solution for the protection against the effects of climate change for the coastal city of Tampa, Florida is examined. The IPCC (2013) predicts an increase in magnitude and frequency of storms in the tropical region. One of the effects of these hurricanes is a high storm-surge, which together with high tide pose a big threat for coastal cities such as Tampa (FLOCC, 2010). The proposed solution for Tampa’s situation is the implementation of a storm-surge barrier based on the structure in the Oosterschelde, the Netherlands. The aim of the study is to assess the influence of the implementation of the storm-surge barrier on the local resilience of Tampa Bay. This study is conducted using interdisciplinary research, which combines the knowledge and theories of ecology, earth sciences and political science and finds common ground (Rutting et al., 2014). The used theories are climate change, resilience, sustainability and the collective action theory. Using literature study and MATLAB modelling simulations, Tampa Bay and the Oosterschelde are compared. The implementation of a storm-surge barrier has some difficulties. Water quality is a main stressor for the ecological resilience, the amount of stakeholders involved in the project is a problem according to the collective action theory and the short-term vision of the politicians also complicates the situation. However when regarding the resilience of the whole social-ecological system, a storm-surge barrier will improve this.
4
INTRODUCTION
The scientific evidence of climate change becomes stronger; sea levels are rising, the average global temperature is increasing and storms are becoming more intensive and their frequency is increasing (Field, 2014). Coastal zones are particularly prone to sea level rise and higher storm intensity (Field, 2014), endangering millions of people living in coastal cities. In order to increase the resilience and enhance sustainability of these coastal regions, adaptation and protection against the effects of climate change is needed. For this paper, a case study will be done for Tampa; a city at the west coast of Florida, USA (fig.1), which is one of the most vulnerable cities for the effects of climate change in the US (Rahmstorf, 2012). Tampa is situated at an estuary: Tampa Bay. It is the largest estuary of Florida comprising 103627 hectares of open water and surrounded by a densely populated area. This study will look at the impacts of a coastal protection structure at the mouth of the Tampa Bay estuary. As the Netherlands is a country, which is highly specialized in water protection, its
knowledge could be used for implementing coastal protection in Tampa Bay. In this study, the Dutch Deltaworks in the south-west Netherlands will be compared to Tampa Bay because that particular area was found to be best fit for the situation of Tampa Bay. In the Oosterschelde, a storm-surge barrier was implemented, which could also possibly be used as coastal protection in Tampa Bay. The aim and the main research question of this study is to assess how the use of coastal protection technology and policy based on the Dutch Oosterschelde storm-surge barrier will affect the resilience of Tampa Bay, (Florida) USA.
In order to make any statements about the resilience and sustainability of such a system and to assess whether this kind of protection is suitable for the Tampa Bay, the Dutch and Tampa Bay coastal system will be compared. In this comparison, hydrological, environmental, ecological and political factors will be taken into account. Furthermore, the ecological impacts of a storm-surge barrier will be assessed in order to make predictions of the ecological impacts of implementing such a structure in Tampa Bay. This comparison and impact assessment will be done using an
5 interdisciplinary approach. This is necessary since implementing a storm-surge barrier is a complex problem, which entails multiple actors. Actors such as politicians and ecosystem services are inter correlated and affect each other in many ways. To be able to research this complex network, relevant theories, methodologies and concepts from multiple disciplines and the insights they generate for a specific problem should be integrated (Rutting et al., 2014). Three disciplines are fundamental to assess whether implementation of the barrier is possible and what the main impacts on nature will be. These disciplines are Earth Sciences, Ecology and Political Sciences and form the basis of this research.
In this paper, the theoretical framework will be addressed first. This paragraph includes the definitions of resilience and sustainability and a section about the effects and future threats of climate change. It also reflects on the implementation of large projects by means of the collective action theory. Next, the research methods will be explained. Then the system of Tampa Bay and the south-west Netherlands will be compared using insights of the previously mentioned disciplines. This section will be followed by the virtual implementation of the barrier, using literature research and computer simulations. In this way the effects of the implementation of the barrier in Tampa Bay will be assessed. The paper will end with a discussion of the results, some recommendations for further research and a general conclusion.
6
THEORETICAL FRAMEWORK
In this section, the theories and concepts that are important for this research will be explained in detail. In order to be completely clear about the definitions of the theories used in the research, it is important that these will be explained. As stated in the introduction, the aim of this research is to increase local resilience in Tampa Bay. It is important to define the concepts resilience and sustainability. These are meaningful concepts when implementing a dyke or barrier in an socio-economic and ecological system. Therefore, the definition of resilience used in this report as well as the application of resilience will be explained. Sustainable development is often implemented in order to increase resilience of a system or an area (IPCC, 2013). Thus, sustainability is closely linked to resilience, and will also be addressed in this theoretical framework. Other theories that will be mentioned are climate change and the collective action theory. Climate change is the reason Tampa is likely to be endangered by floods and therefore pivotal aspect in this research. Collective action theory describes the challenges actors have to overcome in order to handle the implementation of collective goods as efficient as possible.
CLIMATE CHANGE
Table 1: Likelihood terms associated with the outcomes used in the AR (IPCC, 2013)
According to the Intergovernmental Panel on Climate Change (IPCC, 2013), climate change will likely increase the intensity and frequency of storms. Table 1 states the terms of likelihood and the associated probability value used by the IPCC (2013) in their fifth assessment report. Modelling studies have showed it is likely that tropical cyclone frequency and intensity of the most intense tropical storms will increase (IPCC, 2013). Furthermore, climate model simulations predict that it is very likely that overall precipitation will increase for the 21st century in the tropical latitudes, but they also predict a higher variability in precipitation (IPCC, 2013). In combination with sea level rise, this increased intensity and variability could lead to higher flood risks in the tropical region (IPCC, 2013). Together with the population growth and the fact that approximately 40% of the world’s population lives in coastal areas (within 100 km of the coast), this poses a serious problem. The IPCC (2013) states that many water management practices may not be able to cope with these impacts, thus improvement is needed in order to protect coastal cities. This coastal management improvement should be done in a way that incorporates long-term climate impacts into the plan.
In Florida, climate change will likely lead to a higher storm surge, faster flow, higher waves, hydrodynamic pressure and wave impact loads on buildings which will possibly lead to significant
7 damage (Florida oceans and coastal council (FLOCC), 2010). The FLOCC (2010) also predicts that the frequency of major hurricanes in Florida may increase due to climate change. These hurricanes generate a high storm surge, which will be increased by sea-level rise. Storm surge and flood maps can be used in order to assess which regions are most at risk. In the results section of this paper, MATLAB storm-surge modelling outputs will be given for the effects of storms and the
implementation of the storm-surge barrier.
RESILIENCE
The first definition of resilience given in ecology was: “a measure of the persistence of systems and of their ability to absorb change and disturbance and still maintain the same relationships between populations or state variables” (Holling, 1973, p. 14). This definition was followed by others: “the ability of a system to absorb disturbances and still retain its basic function and structure” (Walker and Salt, 2006, p.1). Or in other words, “the concept of resilience in relation to social–ecological systems incorporates the idea of adaptation, learning and self-organization in addition to the general ability to persist disturbance” (Folke, 2006).
As shown, the theory of resilience is still being researched and redefined to find the best way to manage social-ecological systems, in which social-systems and ecosystems are interdependent and integrated into one system (Adger, 2000). Tampa Bay is such a system, in which the social aspects influence the ecological system and vice versa.
A system exists in a stability domain wherein disturbances can be absorbed. If the disturbance exceeds the boundaries of the system, it will shift towards another equilibrium. The stability domain is not defined but subject to change. The dynamic characteristic of the stability domain is called ‘adaptive capacity’ (Scheffer et al., 2001). The adaptive cycle (four-phase model) of Holling (1986) describes this adaptive capacity. It shows how an ecosystem organizes itself and how it responds to changes (ESDN, 2012). Walker and Salt (2006) visualized the concept as shown in figure 3.
The first phase of the adaptive cycle is the rapid growth or exploitation phase (r phase). Examples in ecology are weeds and early pioneers that exploit the freely available resources. At this point resilience is high. When implementing Tampa Bay in this adaptive cycle, this phase could be seen as the start of civilization and rural development in the area. Then the transition to the conservation phase (K phase) occurs, in which competitors are being replaced by specialists and the efficiency of the system grows and components become more connected. Tampa Bay grew out into a vibrant urban area with economic interests and therewith puts pressure on theresources and services of the system. This phase results in loss of flexibility and the system becomes vulnerable for
disturbance. If such a disturbance, for example a flood occurs, the system shifts to the release or creative destruction phase (Ω phase). Climate change, but also the implementation of a storm-surge barrier in Tampa Bay can cause such disturbance. There is loss of structure, but options are open. Next, the system comes in the re-organization or renewal phase (α phase). This phase may lead to a repetition of the previous system, creates a new identity or in the worst case collapses and end in a
8
degraded state (ESDN, 2012). This should of course always be avoided. Therefore this theory will be used to look at the effects of a storm-surge barrier in a phase of conservation.
Politics and management can use the concept of ecological resilience for their decisions although this is not easy, as resilience is difficult to measure. Noticing changes that put the system on a threshold point is hard because it occurs slowly (Walker and Salt, 2006). Furthermore, knowledge about the functioning of very complex ecosystems is limited, and it is unlikely that we gain all the knowledge needed (Holling, 1973). Therefore, in this research, the ecological problems that already occur in the estuary will be examined and discussed to assess the vulnerable parts of ecological resilience. It also examines how the changes in the structure of the social-ecological system can influence this. The structure of the system will change due to the social demand for safety when impacts of climate change become clear. The implementation of the barrier creates disturbances but the reason is to sustain the city and to assure safety for future generations.
SUSTAINABILITY
Though the term sustainability is used very often, not everyone agrees on a clear definition of sustainability. The term is derived from the Latin word ‘sustinere’, which means to maintain, to support or to endure. These words have essentially different meanings, and thus it becomes clear why it is so hard to define sustainability and why several scientists use the term differently. Medovoi (2010) stresses that sustainability is the ability of a system to endure certain impacts, but he does not say in which state the system is after these impacts. The definition of the Oxford dictionary is ‘Able to be maintained at a certain rate or level’, which indicates the importance of a system remaining the same while under the influence of impacts. Though, all these definitions do not incorporate the fact that the Earth is a complicated system that works with balances and feedbacks. Furthermore, the important factor of time is not mentioned, which makes it hard to assess sustainability. Therefore a more holistic definition will be ‘Sustainability creates and maintains the conditions under which humans and nature can exist in productive harmony, that permit fulfilling the social, economic and other requirements of present and future generations (United States environmental protection agency, 2015). This is also the definition that will be referred to when using the term in this paper. When looking at the previously mentioned definition, sustainability has two components; sustaining human life on earth and at the same time not compromising nature by doing so. When implementing this on the situation of the proposed coastal protection structure in Tampa Bay, the human
component is easier to assess than the nature component. The aim of the structure is to protect people living in the cities behind it, therefore the human sustainability will probably be increased by the structure. This will be further assessed in the discussion of this report. This structure could also be called sustainable development or a way of climate resilient pathways, which include strategies, choices and actions that reduce climate change and its impacts (IPCC, 2013). On the other hand it is understandable that the implementation of such a structure will have certain effects on the coastal system. Changes in a systems characteristics and functioning could have effect on the sustainability of that system. In order to assess the sustainability of the system after the alterations by the coastal protection, the changes of the different system characteristics should be fully understood. However, according to Constanza & Patten (1995), it is very difficult to quantify sustainability because the time factor plays a crucial role. As it is the goal of sustainability to sustain a system for future generations, one can only look back from these generations in time if the system was sustained. Making
predictions for future sustainability of a system is therefore extremely difficult. This can only be done using scenario studies, but these usually include a large error margin (Constanza & Patten, 1995). In this study, the different changes in system characteristics will be assessed. By using these changes, the sustainability of the coastal system will be evaluated. Political factors also influence the degree of sustainability because, since the last decade, a tendency from municipal governments towards
9 sustainability was generated (Davidson, 2009). Collective action theory tries to map the problems that could originate from the implementation process of the dike.
COLLECTIVE ACTION THEORY
The Collective Action Theory is a fundamental theory regarding the understanding of group behaviour and was first introduced in 1965 by American economist Mancur Olson. The theory was shaped to elucidate and understand collective behaviour of people who intend to provide a collective or public good in a certain way by collaborating with each other and therewith try to push for
collective action. Collective or public goods are goods that are used by many people and that are not competitive and excludable (Olson, 1965). In other words: goods for everybody to use. This could also be an object that exists without people noticing its existence, a dyke for example. Everybody benefits from the dyke, but people are not always aware of its existence. The storm-surge barrier in the project could be considered a collective good. Furthermore, the theory is based on common interests of groups, individuals or other stakeholders. When several groups participate in a project, every single group expects different things of the project. Due to this, the groups differ in the fields of demands and expectations (Olson, 1965).
Olson (1965) found that the size of the groups that try to implement common goods is very important for the outcome of the process. He concluded that a single individual could hardly influence the process, but on the other hand could form a group to gain influence. However, the groups of individuals are dependent on a maximum size. Groups that are too large are very inefficient and do not create ideal circumstances for the implementation of common goods. Small groups are perform better at this and gain more contribution to the implementation process (Olson, 1965). For example, a study by professor John James (1961) shows that active, decision-taking groups had an average group-size of 6.5 members, whereas non-active subgroups had an average of 14 members.
Another pitfall that could be found during the implementation of a collective good is the freerider-problem. The freerider-problem indicates that some stakeholders contribute more to the
implementation of the common good than others, while every stakeholder benefits of the collective good just as much. Freeriders are the actors or people that contribute less and benefit a lot. The freerider-problem could lead to major problems because the relations between the different stakeholders could deteriorate. This could be detrimental for the collaboration (Marwell & Ames, 1979).
During this research, collective action theory will be used to determine which challenges should be overcome in order to maximize the success of the implementation of the storm-surge barrier in Tampa Bay.
10
RESEARCH METHODS
Implementing a storm-surge barrier is a complex problem because it entails multiple agents (e.g. the government and fish species) that are intercorrelated and affect each other in many ways. All these different agents are represented by different academic disciplines, but the complex problem is more than a sum of disciplines (Rutting et al., 2014). Therefore, interdisciplinary research is needed. In interdisciplinary research, relevant theories, methodologies and concepts from different disciplines and the insights they generate for a specific problem, are integrated (Rutting et al., 2014). Therefore, our research contains both reductionism (specific and in-depth knowledge per discipline) and holism (integration of the different insights) (Rutting et al., 2014).
This research is based on the disciplines earth sciences (hydrology and physical geography), ecology and political science. These disciplines will give different insights into the complex problem a storm-surge barrier entails. Earth sciences is of great importance in this matter because it can show whether and how it is possible to build a storm-surge barrier and to what extent the barrier will change hydrology and the environment. Ecology is able to give answers on the ecological effects a storm-surge barrier may induce which is closely related to the hydrological changes. Political science in its turn plays an important role as it can show to what extent national government can make the implementation of a storm-surge barrier successful, taking into account the many different
stakeholders and interests.
In order to answer the research question, the different insights should be integrated by finding common ground and overcome discrepancies in theories and assumptions (Rutting et al, 2014). The theory of collective action is connected with the theory of sustainability, because regulations made in politics have great influence on the degree of sustainability. Furthermore, sustainability and climate change both influence resilience, as the use of resources and the change by climate affect the robustness of “the system”. The resilience of “this system” is the assumption in which all the disciplines need to find common ground. Therefore, modification of the assumptions of resilience is necessary and secondly it needs to be connected around one central idea (Repko, 2012). Earth scientists, ecologists and political scientists all think in their own system. Earth sciences look at the resilience of the environment and hydrology. Ecologists look at the state of the ecosystem(s) and political scientists are mainly interested in the use of sustainable management in order to manage resilience in terms of policy. However, all these systems are interconnected into one system and therefore in this research Tampa Bay is integrated into one system: a social-ecological system. Resilience therefore comprises the degree of protection of Tampa, the robustness of the ecosystem, and the buffer capacity of the environmental changes.
To be able to overview the implications of building a storm-surge barrier in the mouth of the Tampa Bay estuary, several research methods will be used. First of all, a literature study was performed in order to gain knowledge about the area of Tampa and to collect comparative material from Dutch coastal protection structures, both on ecological, hydrological, physical geographical and political aspects. Secondly, a script for a model will be written to perform an assessment of the influence of a storm-surge barrier in the area of Tampa Bay. This script will be written in Matlab. The outcome will
11 Figure 4: Schematic map of barriers in the province of ‘Zeeland’ in the Netherlands. 0-Kreekdam, 1-Zandkreekdam, 2- Veersegaldam, 3-Grevelingendam, 4-Volkerakdam,
5-Haringvlietdam, 6-Brouwersdam, 7-Oosterschelde storm-surge barrier,
8-Philipsdam, 9-Oesterdam (Nienhuis & Smaal, 1994)
be maps, which indicate the flooded places with different storm surges with and without barrier. The maps will also show other weak locations in the protection against flooding.
RESULTS
TAMPA BAY VERSUS SOUTH-WEST NETHERLANDS
COASTAL PROTECTION IN SOUTH-WEST NETHERLANDS
For centuries, the Dutch have been known for their innovative water management. Estuaries have been a problem for them as well as it is becoming for the people in Tampa. Dutch knowledge about coastal protection is used worldwide (Deltaworks, 2004a). In this section the Oosterschelde storm-surge barrier and the storm-storm-surge barrier ‘Nieuwe Waterweg’ in the Netherlands will be discussed on technical, environmental and political aspects to be able to compare the situation of Tampa Bay to that of the Netherlands.
In the Netherlands, coastal protection can be found along the coastline in the form of dykes, dunes or surge barriers. One of the largest deltaworks in the Netherlands is the Oosterschelde storm-surge barrier (Deltawerken, 2004a) (Deltawerken, 2004b). This project created new knowledge about coastal protection and costed about 2.5 billion euros. The decision by the government for an open structure was made after an advice report of the Delta-commission (Deltawerken, 2004c). In the year 1977, the Delta-commission published an advice report on the construction of the Delta Works in the south-west of the Netherlands. One of the main topics in the report was the design of the different storm-surge barriers in the province of Zeeland. Actually, the commission decided that the Westerschelde’ and the ‘Nieuwe waterweg’ (see fig. 4, (Nienhuis & Smaal, 1994)) had to stay open, in accordance with the economic interests of the ports of respectively Antwerp and Rotterdam (Deltacommissie, 1977). Just like these Dutch water bodies, Tampa Bay has to stay open in
accordance with economic and ecological interests. The Oosterscheldekering itself, which is shown in figure 6, did not have to stay open for this particular reason (Nienhuis & Smaal, 1994). The choice for an open construction of the Oosterscheldekering was because the Oosterschelde had to remain salty in order not to harm the unique ecosystem (Deltacommissie, 1977). The suggested project in Tampa will consist of a combination storm-surge barrier that on the one hand is partly open to ensure the passage for ships to the estuary, and on the other hand consists of sluices to ensure that the estuary stays in direct contact with the salty water from the sea.
12 The construction of the Oosterschelde storm-surge barrier took about 7 years. The distance that had to be covered was nearly 9 kilometres in total. The open structure covers 3 kilometres of the total construction; the other 6 kilometres are closed by a dam (Rijkswaterstaat, 2014). The construction shown in figure 5 (Deltawerken, 2004c) is heavy; piers used in the construction weigh approximately 18 ton (Nienhuis & Smaal, 1994). Therefore the floor of the Schelde had to be consolidated and reinforced with synthetic mats filled with sand and gravel. After this treatment, the underground of the barrier was strong enough to carry the weight of the piers and slides. The piers and slides had to be produced with high precision and had to close perfectly in order to stop surges (Deltawerken, 2004c). The slides protect the land up to a storm surge of 5.80 meters above sea level
(Rijkswaterstaat, 2014) and at this moment, the barrier creates safety for the people in the
Netherlands. However climate change is affecting discharges of the Oosterschelde as well as causing sea level rise. Innovation will always be necessary, to keep the people safe and to sustain the environment (Deltawerken, 2004d).
The last construction built in the province of Zeeland, was the ‘Maeslantkering’ (fig. 6). This storm-surge barrier is able to close the Nieuwe Waterweg when the storm storm-surges become high
(Deltawerken, 2004e). In this way, ships are able to pass through, which is not possible at the Oosterschelde storm-surge barrier.
The unique ecosystem of the Oosterschelde estuary had to be maintained. Before the storm surge barrier was built, it consisted of an estuary with unpolluted water with a discharge of 70-80 m3/s. The water in the estuary was well mixed throughout the year because of the North sea and its morphology, the tidal amplitude and the very low freshwater supply by the Oosterschelde. The estuary is not very deep; the deepest part has a mean depth of 12 meters and the other three parts are shallower than 5 meter (Scholten et al., 1990). The water also contains many nutrients, which are used for primary production (Wetsteyn et al., 1990).
TAMPA AND TAMPA BAY
Tampa Bay is a large, shallow (4 m) estuary, which is connected to the Gulf of Mexico. Tampa Bay extends inland by approximately 56 km and consists of three primary segments: the main body of Tampa Bay (Lower and Middle), Old Tampa Bay and Hillsborough Bay, which can be seen in figure 7. Fresh water comes in from four rivers: the Hillsborough, the Alafia, the Manatee and the Little Manatee river with annually flow range around respectively 15, 13, 10 and 6 m3/s , respectively (Zhu et al., 2015). The tidal current amplitudes range between 0.5 and 1.0 m/s and the mean tidal height is 0.7 m (Berman et al., 2005).
Figure 5: The ‘Oosterscheldekering’ (Deltawerken, 2004c)
Figure 6: The Maeslantkering (Deltawerken, 2004e)
13 According to Rahmstorf (2012), Tampa Bay is one of the high vulnerability ‘hotspots’ to sea level rise in the US. The expected sea level rise for 2030 and 2050, compared to 2008, are respectively 0.13m and 0.31m. The height of the storm surges is expected to be 1.57 m above mean high water (MHW) for 2050 and 1.94 m above MHW within a 100 years (Tebaldi et al., 2012).
The morphological features of Tampa Bay have mostly been determined by events of the Pleistocene (Doyle et al., 1989). During periods with a lower sea level, rivers have cut a shallow valley into the bay. Within this valley, channels were cut with a maximum of 2 m deep. Karst systems have also created the valley floor, as sinkholes have developed in the limestone. When the sea level rose again, the valley with its channels and sinkholes was flooded. According to Doyle et al. (1989), the
sediments are dominated by quartz sand and some shell material.
At this moment, Tampa Bay is constantly influenced by storms and tidal currents. The Bay has three inlets to the sea spread over three kilometres: Egmont Channel, Southwest Channel and Passage Channel (Berman et al., 2005). The inlets are considered to be tide dominated. However, the tidal energy is relatively low.
Due to its large size, the gradient of salt- to freshwater and its location in a transition zone of a warm, temperate and tropical climate, the bay provides a suitable environment for many diverse species to settle (Greening and Janicki, 2006). The richness of the area is represented by approximately 40000 wading and shore birds of 25 species that annually nest on the islands in the bay, like the brown- and white pelican and the spoonbill. Furthermore, over 200 fish species spend some part of their lives in the estuary of Tampa Bay. Also silver tarpon, dolphins, sea turtles, and manatees occur (TBEP, 2015). Examples of suitable habitats for species are seagrass beds, salt marshes, mussel reefs, mangrove forests, clam flats, oyster reefs and unvegetated bottom (TBEP, 2015). These habitats are a vital part of the coastal and estuarine ecosystem, providing refugia, migration pathways, spawning grounds, nurseries and feeding opportunities (Greening & Janicki, 2006).
These habitats however have been declining since the 1950s because of water quality degradation and physical disturbance. The current water quality of Tampa Bay is heavily influenced by the
14 growing urban areas around the coastline. Eutrophication caused by increasing nitrogen
concentrations pose a serious problem (Wang et al., 1999). Other sources of sediment that influence the water quality of Tampa Bay are storm water, river runoff, dredging and transportation activities (Chen et al., 2007). These effects haves the biggest impact on seagrass meadows, that cannot get enough light because of the presence of excessive amounts of phytoplankton that arise due to eutrophication (Wang et al., 1999). This is a serious problem, because seagrasses have been
identified as a key environmental resource (Larkum et al., 2007). Seagrasses provide habitat for many environmentally and economically important shellfish and fish species, and function as a food source for marine mammals (e.g. manatee) and other wildlife. Furthermore, it plays an important role in improving stability of bottom sediments and nutrient cycling (Larkum et al. 2007).
With regard to monetary value, seagrass meadows and submerged algal beds have been estimated to be worth approximately $3,116 per ha per year (in 1994 U.S. dollars) in providing ecosystem services (Costanza et al. 1997). In total, the current estimate of seagrass is 12,000 ha (Greening & Janicki, 2006) which means that it provides an income of $37.392.000 (in 1994 U.S. dollars) per year. Its functions and value show that seagrass is important for the social-ecological system.
Environmental stakeholders are able to protect (for example) sea grass meadows during joint decision-making processes. During this research, the interests of three environmental actors were examined. These are ‘Tampa Audubon Society’, ‘Tampa Bay conservancy’ and ‘Tampa Baywatch’. By examining the interests of these stakeholders, a common thought was generated: All organisations aim for the conservation and restoration of the Tampa Bay ecosystem and thereby protect natural habitats, native wildlife and scenic views. (Tampa Audubon Society, 2015), (Tampa-Bay conservancy, 2015), (Tampa Baywatch, 2015). Table 2 gives an overview of some important stakeholders present in Tampa Bay.
Table 1: An overview of the key-actors in the decision-making process concerning the implementation of the storm-surge barrier in the Tampa-Bay estuary.
15 The shape of the barrier plays an important role concerning passage possibilities for industrial
stakeholders. This section will indicate the monetary value of the Bay’s ports.
Tampa Bay estuary comprises three seaports, with Port Tampa Bay as the most important
stakeholder. Combined, the three ports contribute 15 billion dollar to the local economy and provide the state with about 130 thousand jobs (Tampa Port, 2014). Furthermore, the port takes the 22nd place in the field of ‘total trade value’. In 2013, this amount stated 32.5 million tons (AAPA, 2015). This number includes data of imports, exports, domestic- and foreign trade. Finally, the port plays a key role in the field of tourist transportation and accessibility. The average number of passengers per year reached 900 thousand passengers. This is an average of nearly 200 cruise ships a year (Tampa Port, 2014).
Municipalities represent the Tampa-Bay citizens’ interests, and therefore are considered
stakeholders and exert pressure on Governmental stakeholders. In terms of population, the need for an storm-surge barrier is needed. In 2013, the Tampa Bay area possessed an total population of 4.35 million people. The projection for 2018 totals up to 4.55 million (Tampa Bay Demographics, 2015). At the moment, the American Congress (the largest governmental stakeholder), consists of a majority of republicans in relation to democrats. This goes for both the Senate and the House of Representatives (American Congress, 2015). The current republican state of the Congress, combined with a democratic president could lead to problems, mainly because the interests of these parties differ. Most Republicans deny human activity as the main cause for global warming (Dunlap & McCright, 2008). Floridian Governor Rick Scott is republican and does not believe in climate change caused by human activities (Caputo, 2015). This could lead to implementation issues concerning environmental projects like the one in this research.
NEW ORLEANS EXAMPLE
Since there has never been an environmental coastal protection project in the United States like the one this project proposes, research has to be done on the basis of assumptions and previous projects that show some similarity with our project. In order to illustrate American national implementation policy in a more concrete way, a decision-making chronology on the basis of a project from 1965 in New Orleans described by Woolley (2007) is briefly discussed in appendix II. It describes the chronology of the implementation of a ‘Barrier-plan’ in New Orleans as a reaction on high water levels in the area.
The New Orleans example shed light on some elements during the implementation of large projects. It described a funding that was partly generated by Congress (70%) and partly by local sponsors (30%). At first, to guarantee contribution from both Congress and sponsors, policy makers in Tampa Bay have to assure that the bay’s economical attractiveness can be maintained. This could be done by implementing a special structure into the surge barrier, similar to the Dutch Maeslantkering, in order to create a passageway for container vessels and cruise ships. Secondly, policy makers have to make sure they are able to provide an overview of all costs that are involved with the construction of the barrier. Thirdly, policy makers have to assure that all ecological effects are mapped within an ‘Environmental Impact Statement’ (EIS). The content of the EIS has to correspond with the content stated in the ‘National Environmental Policy Act’ (NEPA).
Lebel et al. (2006) argues that governance for example is not only influenced by state policy; it arises from the interaction between actors of all kinds. According to collective action theory, the
collaboration between many stakeholders in Tampa Bay with corresponding interests could be problematic. Moreover, the group size of Congress combined with a majority of republicans could hinder implementation plans according to collective action theory.
16 Table 3: Height storm surges of evacuation levels Figure 8: Digital Elevation Model of Tampa
RESILIENCE
When implementing a construction like a storm-surge barrier, as described in the theoretical framework, the resilience of the system is important. In this part, multiple factors of resilience in Tampa Bay will be assessed to research how it is affected. These factors include the degree of protection of Tampa, the robustness of the ecosystem, and the buffer capacity of the environmental changes.
First, convincing the politicians of Florida of the implementation of a storm-surge barrier in Tampa Bay will be difficult. As mentioned before, the majority of republicans and governor Scott do not believe in climate change as an effect of human activity. Moreover, dealing with long-term dynamics is a difficult task, both in science and in practical decision making (Klauer et al., 2013; Clark &
Dickson, 2003). Only when collective action problems, short-term oriented policy and denial of climate change can be overcome, there is a chance of implementing a barrier. However, first it should be determined whether the implementation of a barrier can actually protect the city, in order to secure the resilience of the social factor (e.g. the people) of the socio-ecological system.
MODELLING STORM SURGES
To protect Tampa, the Tampa Bay estuary (fig. 8 ) has to be enclosed with an open structure. As mentioned earlier, the seafloor of Tampa Bay consists mainly of quartz sediments and limestone (Doyle et al., 1989). Quartz is a relatively robust material, but limestone is not, so consolidation might be needed. The main barrier will cover a distance of about 12 kilometres.
In order to assess the impact of storm surges in Tampa Bay, a model was written in Matlab (see Appendix I). A barrier was implemented in the original digital elevation model of Tampa Bay. This Digital Elevation Model was provided by National Centers for Environmental Information in the USA(2015) . The evacuation guideline of the area gives an indication of the storm surge possible in Tampa Bay, as shown in table 3. Storm surges are
dependent on factors like wind speed, direction and air pressure. It is therefore hard to say something about when such high storm surges occur. Hurricanes of category 4 have hit Tampa Bay in history and it is expected to happen again (Weisberg & Zehn, 2006). The last time a hurricane of this category hit Tampa Bay, it caused storm surges between 3 and 3.5 meters (Ballinburg, 2006).
Evacuation level Storm surge height in meters
A 1,2-2,5
B 2,5-4,3
C 4,3-5,8
D 5,8-7,9
17 Figure 9: Output DEM, storm surge of 2.5 meters
with barrier
Figure 10: Output DEM, storm surge of 3 meters with barrier
Figure 12: Output DEM, storm surge of 4.3 meters with barrier
Figure 11: Output DEM, weak locations in Tampa Bay
First, the model was runned with a storm-surge height of 2.5 meters. After each run, the storm-surge height was increased with 0.5 m.
18 Figures 9 and 10 indicate that the barrier can hold the water up to 2.5 m storm-surge. When
exceeded, the surrounding areas will flood. Therefore, in order to protect Tampa against such high storm-surges, barriers on other vulnerable locations have to be implemented as well. Figure 11 shows these locations, which need extra protection. There are 2 locations through which the water enters the bay and surrounding areas (visible in the circles in fig. 11). If these locations are enclosed by a barrier or dam, the water can be hold up to a higher level. It should at least be possible to protect the area from storm surges of 4.3 meters, at which the evacuation plan is covered until level B (figure 12).
OOSTERSCHELDE VERSUS TAMPA BAY
Before the implementation of the storm-surge barrier in the Oosterschelde, research was done on the effects of the construction by for instance Delta Commision. The environmental effects of a complete closure of the Oosterschelde would have been drastic, thus a storm-surge barrier has been implemented. Because the barrier allows the tides to enter the estuary, it safeguards the essential dynamics of the ecosystem (Smies & Huiskes, 1981).
However, the storm surge-barrier still decreased the exchange of water between the North Sea and the Oosterschelde. After the construction of the Oosterschelde storm surge barrier, a couple of things changed. The tidal current was lowered by 25%, as a result of the decreased width of the mouth of the estuary (Deltawerken, 2004), which also reduced turbulence and caused a higher transparency of the water. This resulted in a higher light availability for primary producers (e.g. water plants, algae and phytoplankton) which led to a higher primary production of the ecosystem
(Wetsteyn et al., 1990). It was however counteracted by the lowered nutrient concentrations, which was caused by the decreased freshwater inflow by the Rhine and Meuse which are blocked by dams (Scholten et al., 1990). This formed a new limiting factor for the primary producers, but production remained in equilibrium.
The Oosterschelde and Tampa Bay are both ebb-tidal systems, so they are comparable systems. For that reason, an increase of the transparency of the water will probably also occur in the Tampa Bay estuary as well. However, Tampa Bay has a lower average tide of 0.7 m compared to the tide of 2.9 m of the Oosterschelde. Therefore, it can be suggested that the effect of the storm surge barrier on the tidal system will be relatively low for Tampa Bay. Moreover, the effect probably will be different because when considering the ecological impact of a storm-surge barrier, one main difference between the Dutch and American estuaries should be taken into consideration. This difference is that the Oosterschelde was and still is relatively unpolluted and lies in a scarce inhabited area (Nienhuis and Smaal, 1994). On the contrary, Tampa Bay is a densely populated area and suffers disturbance and pollution (Chen et al., 2007). Thus, although the tidal change will be less, the system in Tampa Bay will be more vulnerable for change.
This pollution is the source of eutrophication. As already mentioned in this report, it causes excessive blooming of phytoplankton (Wang et al., 1999) with reduction of sea grass meadows as a
consequence (Gallegos, 2001). Transparency due to the implementation of a storm-surge barrier will enhance the growth of phytoplankton even more and loss of sea grass beds will increase as well. Since sea grass beds have a valuable role in the ecosystem, this would have great impact on the health of the estuary (TBEP, 2015).
However, if management practices are able to limit the effects of eutrophication and make nitrogen a limiting factor again, the opposite effect could appear. Primary production would increase like in the Oosterschelde (Wetsteyn et al., 1990), and sea grasses would be better able to return, making use of the increased light availability caused by the higher transparency of the water.
19 Furthermore, the channels in the Oosterschelde changed orientation. This reorientation could be caused by the interaction between the longshore current and the tidal current, which changed. There was an overall decrease in morphological activity, which meant less formation of bedforms and less bed level changes. Wave-driven morphological activities became more important (Eelkema et al., 2013). These effects enhanced erosion of intertidal flats. This caused a reduction of oyster banks and saltmarshes, and subsequently a decrease in food provision for birds. Measures now take place to reduce the impacts, including the placement of artificially constructed oyster banks and the
restoration of saltmarshes (Cozolli et al., 2014). Moreover, less inundation of salt marshes caused a transient change in zonation of the vegetation (de Leeuw et al., 1994). On the other hand,
improvements for macrozoobenthic species occurred in the Oosterschelde estuary. The quality of the sub-tidal benthic habitat increased. Because the current stress lowered, macrozoobenthic organisms could colonize a vast part of the Oosterschelde, which usually were confined to more sheltered portions of the estuary (Cozolli et al., 2014).
Overall, the decrease in intensity of tidal currents is the main effect in the ecosystem of the Oosterschelde estuary. Yet the biological communities only showed quantitative shifts into other assemblages (Cozolli et al., 2014), little effects in the zonation of saltmarsh vegetation (de Leeuw et al., 1994) and changes in species dominance. Therefore, the assumption can be made that the ecological resilience of the Oosterschelde estuary was high enough for the system to adapt to the barrier in order to stay in the same stability domain.
It is plausible that the ecosystem of the Tampa Bay estuary will experience similar effects in quantitative shifts, zonation and changes in species dominance. However, the latter will have a damaging effect in Tampa, which is not the case for the Oosterschelde. As an effect of enhanced eutrophication, the increased dominance of phytoplankton will harm the ecosystem. It will especially cause decrease in sea grass which forms a valuable habitat, thus a decrease will affect the entire ecosystem. There can be concluded that sea grass meadows form a weakness in the Tampa Bay estuary, which affects ecological resilience. Since building a storm-surge barrier will enhance this vulnerability, resilience will be put on the test even more.
20
CONCLUSION AND DISCUSSION
In this interdisciplinary research report, the resilience of the social-ecological system of Tampa was assessed after the virtual implementation of a storm-surge barrier. First it should be said that based in the model predictions made during this study and the outcomes of the fifth assessment report of the IPCC (2013), the impacts of climate change on the resilience and sustainability of Tampa Bay without coastal protection will be significant. However, the effects of the implementation of the barrier should also be assessed. The Oosterschelde and Tampa Bay were compared in order to gain knowledge about the possible implementation of the Oosterschelde storm-surge barrier and its effects on the resilience of the socio-ecological system. During this research, several complications and possible negative effects were found. Therefore, the resilience of the socio-ecological system will probably change after the implementation of the barrier. Though, as previously mentioned,
resilience is rather difficult to measure. Therefore, a few vulnerable spots in the system that could affect the resilience will be mentioned in this section. Based on these, a few recommendations are made for further research on this topic.
The Oosterschelde storm surge barrier and the Measlant barrier required a high precision during the construction. The sea floor had to be able to carry a construction with heavy piers and slides. All parts had to be designed for the specific locations (Deltawerken, 2004c,e), but the concept could be applied to different locations as well. This means that it is probably possible to implement a structure like the Oosterschelde storm-surge barrier and the Maeslant barrier in the Tampa Bay estuary. As the ocean floor of Tampa Bay partly consists of porous limestone (Doyle et al., 1989), it probably has to be consolidated as well. However, a large storm-surge barrier on itself is not likely to offer enough protection for Tampa. The area around the bay is too low for storm surge heights above 2.5 m. At least two locations have to be heightened, either by other storm-surge barriers and/or dams. The structure proposed for allowing ships to pass through could be implemented on a smaller scale as well. However, even then the surrounding coastal zone is not high enough to protect the land from storm surges higher than approximately 4.3 m. Such storm surges could occur and are mentioned in the evacuation plan of the area.
However, when the technical problems can be overcome there is another problem which occurs. Many different stakeholders have interests by the implementation of such a structure. The collective action theory states that when the amount of stakeholders is too large it can be hard to make decisions on collective goods. Furthermore, the short term vision of the politicians in Tampa Bay as well as in Florida and in the National Government is problematic when dealing with adaptation to climate change. Moreover, the New Orleans case-study cannot be considered completely covering with regards to the Tampa Bay case, since the area differs in the fields of politics, ecology and geography.
A weak spot in the resilience of the ecosystem is the decrease in water quality and the risk of increasing eutrophication and its effects on the primary producers. As the barrier allows the tides to enter the estuary it safeguards the essential dynamics of the ecosystem. However, tidal current will be lowered by a quarter. This will cause effects of quantitative shifts, different zonation and changes in species dominance. Decreased tidal current will mainly cause the water in the bay to become clearer as sediment particles will precipitate more easily. This could enhance the already upcoming dominance of phytoplankton due to eutrophication. The valuable habitat of sea grass meadows already suffers from phytoplankton blooming and will be threatened even more. To overcome this problem, measures against eutrophication should be taken to stop the excessive blooming of algae. Then, it is assumed that the clearer water caused by the storm-surge barrier could even enhance the rehabilitation of the sea grass beds as more light is available.
21 In this search for resilience in the socio-ecological system, not all the necessary disciplines are taken into account. The barrier could not be designed by a geo engineer and the cost could not be
predicted by an economist. Both influence the socio-ecological system and therefore the resilience of Tampa Bay.
In conclusion it can be said that assessing the resilience of a socio-ecological system when implementing coastal protection is a complex problem with no definitive solution. Though, weak spots in the system can be identified and should be overcome or closely monitored in order for the system to remain resilient and sustainable for human life. However, this sustainability can only be assessed after the implementation of the structure, since it involves the influence on future generations.
RECOMMENDATIONS
If the area desires protection against climate change, it is highly recommended for the government to take a good look at the construction this research proposed and to also consult other possibilities for coastal protection. Dutch knowledge could play a key role in this research. However, the governor of Florida does not believe in climate change, although Florida is one of the most vulnerable places on earth for climate change.
If one is to implement such a structure as suggested in this paper, more research will be needed. First, technical research is needed on the practical implementation of the structure, for example the preparation of the sea floor. Furthermore, it is necessary to conduct research on a temporary excavation site from which the piers included in the structure can be built. Secondly, more research is needed to map the involved political and non-political actors and their corresponding interests, in order to guarantee and monitor full collaboration of the stakeholders. There is also an urgent need for knowledge on the distribution of habitats and species, in order to predict the possible effects a barrier will have on the marine ecosystem. This paper has tried to address as many ecological impacts as possible, but due to poor knowledge on species distribution, only little can be predicted. Last, the costs should be taken into account when planning to implement coastal protection.
22
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26
APPENDIXES
APPENDIX I
MATLAB SCRIPT
%% USING DUTCH COASTAL MANAGEMENT FOR PROTECTION AGAINST THE EFFECTS OF.. % CLIMATE CHANGE IN TAMPA BAY (FLORIDA), USA
% RESULTS, VIRTUAL IMPLEMENTATION OF BARRIERS, MODELLING STORM SURGES % COURSE: INTERDISCIPLINARY PROJECT
% SUPERVISORS: MAARTJE HAMERS AND KENNETH RIJSDIJK
% WRITTEN BY: DORIEN VAN KRANENBURG, SOPHIE BAARTMAN, LISA BIBBE AND .. % BRAM VONSEE
%%%%%%%%%%% INITIALISATION %%%%%%%%%%%%%%%%%%%% CLOSE ALL
% LOAD DATA
% DEM_TAMPA = IMREAD('TAMPA_DEM.TIF');
% DEM_TAMPA = DEM_TAMPA(:,5000:LENGTH(DEM_TAMPA'));
% CONTROL CONSTANTS
[NRROW, NRCOL] = SIZE(DEM_TAMPA); % NR OF ROWS AND NR OF COLUMS IN DEM
% SYSTEM PARAMETERS
SURGE = 3 % STORM SURGE IN METERS
% SYSTEM VARIABLES
DEM_FLOOD = ZEROS(NRROW, NRCOL); % EMPTY DEM FOR CREATING STORM SURGE
DEM_BARRIER = ZEROS(NRROW, NRCOL); % EMPTY DEM FOR CREATING BARRIER
DEM_TBARRIER = DEM_TAMPA; % BASIS OF DEM TAMPA BAY WITH BARRIER ..
% STARTS WITH ORIGINAL DEM OF TAMPA ITERATIONS = 0; % NR OF ITERATIONS
%%%%%%%%%%%% CREATING DEM_TBARRIER, THE BARRIER IN TAMPA BAY %%%%%%%%%%%%% % DEM1 = (DEM_TAMPA>=12); % CREATING A DEM WHICH INDICATES LAND ABOVE 12 METERS
% FIGURE
% IMAGESC(DEM1)
%COORDINATES DERIVED FOR THE LARGE BARRIER FROM THIS FIGURE: (8168,5469)(9483,6784) % FROM THESE COÏ¿½RDINATES THE FUNCTION Y = X -2699 CAN BE DERIVED
27 % Y = X - 2699;
FOR Y = 5460:5476; % BARRIER IS 16 GRIDCELLS BROAD, NOT ...
% REALISTIC BUT WATER CANNOT GO THROUGH
FOR X = 8168:9483 ; % BARRIER STARTS IN X DIRECTION AT 8168 ...
% AND STOPS AT 9483
DEM_BARRIER(Y,X) = 12; % BARRIER IS 12 METERS HIGH
Y = Y+1; % CREATING A SLANTING LINE BY COUNTING UP END
END
% COORDINATES DERIVED FOR A WEAK LOCATION IN THE SURROUNDING AREA OF THE % BAY: (6700,4800)(7500, 5400) FROM THESE COORDINATES THE FUNCTION Y = % 0.75X -225 CAN BE DERIVED FOR Y = 4795:4805 FOR X = 6700:7500 DEM_BARRIER(Y,X) = 12; END END
% COORDINATES DERIVED FOR A WEAK LOCATION IN THE SURROUNDING AREA OF THE % BAY: (7600,1800)(8100, 1100) FROM THESE COORDINATES THE FUNCTION Y = % 0.75X -225 CAN BE DERIVED FOR Y = 1795:1805 FOR X = 7400:8100 DEM_BARRIER(Y,X) = 12; Y = Y-1; END END
% FOR ALL THE ROWS AND ALL THE COLUMNS REPLACING VALUES IN THE
% DEM_TBARRIER THAT ARE LOWER OR EQUAL TO THE DEM OF THE BARRIER WITH THE % VALUES OF THE BARRIER
FOR I = 1:NRROW; FOR J = 1:NRCOL;
IF DEM_TAMPA(I,J) >= DEM_BARRIER(I,J); DEM_TBARRIER(I,J) = DEM_TAMPA(I,J); ELSE DEM_TBARRIER(I,J) = DEM_BARRIER(I,J);
28
END END END
CLEAR DEM_BARRIER
CLEAR DEM_TAMPA
%%%%%%%%%%% CREATING A FLOOD %%%%%%%%%%%%%%%%%%%%%%%%%%%%
DEM_FLOOD = DEM_TBARRIER; % EMPTY DEM_FLOOD IS FILLED WITH THE
% VALUES OF DEM_TBARRIER
DEM_FLOOD(5000, 4000) = DEM_FLOOD(5000, 4000)+ SURGE; % ONE POINT IN THE
% WATER GETS HEIGHT OF SURGE
% FROM THE POINT(I,J) OF CALCULATION THE DEM_FLOOD WILL BE COMPARED WITH % THE GRIDCELL NEXT TO IT ONE COLUMN BEFORE AND AHEAD OF IT AS WELL AS THE % ROWS ABOVE AND UNDERNEATH THE GRIDCELL, THE 'NEW GRIDCELL'. WHEN THE NEW % HAS A LOWER VALUE THAN THE CENTRAL GRIDCELL, THE VALUE OF THE
% 'NEW GRIDCELL' WILL BE REPLACED WITH THE VALUE OF THE CENTRAL GRIDCELL.
EDGE = [5000,4000]; % STARTING POINT OF CALCULATIONS STORM SURGE
WHILE SIZE(EDGE, 1) > 0 % AS LONG AS THERE ARE POINTS THAT HAVE
% TO BE CALCULATED THE LOOP WILL BE REPEATED NEW_EDGE = []; FOR P = 1:SIZE(EDGE, 1) POINT = EDGE(P, :); I = POINT(1); J = POINT(2);
IF J < NRCOL && DEM_FLOOD(I, J) > DEM_FLOOD(I,J+1) DEM_FLOOD(I,J+1) = DEM_FLOOD(I, J);
NEW_EDGE = [NEW_EDGE; I,J+1]; END
IF I < NRROW && DEM_FLOOD(I, J) > DEM_FLOOD(I+1,J) DEM_FLOOD(I+1,J) = DEM_FLOOD(I, J);
NEW_EDGE = [NEW_EDGE; I+1,J]; END
IF I > 1 && DEM_FLOOD(I, J) > DEM_FLOOD(I-1,J) DEM_FLOOD(I-1,J) = DEM_FLOOD(I, J); NEW_EDGE = [NEW_EDGE; I-1,J];
END
IF J > 1 && DEM_FLOOD(I, J) > DEM_FLOOD(I,J-1) DEM_FLOOD(I,J-1) = DEM_FLOOD(I, J);
29
NEW_EDGE = [NEW_EDGE; I,J-1]; END
END
EDGE = NEW_EDGE; % STORING LOCATIONS OF CELLS THAT HAVE % TO BE CALCULATED
% VISUALISION DURING CALCULATIONS IF MOD(ITERATIONS, 2000) == 0 FIGURE IMAGESC(DEM_FLOOD, [0 60]) COLORBAR DRAWNOW END
ITERATIONS = ITERATIONS +1; % COUNTING NR OF ITERATIONS NEEDED
END % SIZE(EDGE, 1) > 0
%%%%%%%%%%% SAVE DATA %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% % SAVE('DEM_FLOOD_3', '-MAT') % NAMES HAVE TO BE SPECIFIED TO STORM SURGE HEIGHT % SAVE('DEM_TAMPA', '-MAT')
% SAVE('DEM_TBARRIER', '-MAT') % SAVE('DEM_BARRIER', '-MAT')
%%%%%%%%%%% VISUALISATION %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
FIGURE
SUBPLOT(1,2,1)
IMAGESC(DEM_FLOOD25, [0 60]) COLORBAR
COLORMAP(JET) % ADJUSTED BY HAND
TITLE('STORM SURGE OF 2,5 METERS WITH BARRIER')
SUBPLOT(1,2,2)
IMAGESC(DEM_FLOOD3, [0 60]) COLORBAR
COLORMAP(JET % ADJUSTED BY HAND TITLE('STORM SURGE OF 3 METERS WITH BARRIER')
FIGURE
IMAGESC(DEM_TAMPA, [0 60]) COLORBAR
30
TITLE('DIGITAL ELEVATION MODEL OF TAMPA') FIGURE
IMAGESC(DEM_FLOOD3 - DEM_FLOOD25, [0 2]) COLORBAR
COLORMAP(JET) % ADJUSTED BY HAND TITLE('WEAKLOCATIONS AROUND TAMPA BAY')
FIGURE
IMAGESC(DEM_TAMPA, [4.3 60]) COLORBAR
COLORMAP(JET) % ADJUSTED BY HAND TO SURGE HEIGHT TITLE('STORM SURGE OF 4.3 METERS')
APPENDIX II
NEW ORLEANS CASE
The city of New Orleans, just like Tampa, is a very low lying city and faces similar problems in the field of vulnerability to floods and water nuisance. In 1962, the New Orleans district plotted a new plan to protect the city to floods. The plan titled ‘Barrier Plan’ consisted of several ‘surge barriers’ that should be placed in the passage to lake ‘Pontchartrain’. Due to these structures, the surges were hindered to enter the lake which would reduce the chance of floods in the area. During the making of the plan, engineers calculated the dimensions of these structures by means of the ‘probable
maximum hurricane’ (PMH).
This PMH was calculated to indicate the largest storm the barrier had to be able to withstand. In 1965, the US Congress gave permission to execute the Barrier Plan. It also promised to fund 70 percent of the money needed for the plan. The other 30 percent had to be funded by local sponsors. These sponsor either sponsored in cash, or by the provision of land to allocate the structures. After the permission, the New Orleans district developed a detailed plan to actually build the structures. It also made sure the money was provided and the land was allocated. The project was estimated to be finished in the mid-to-late 1970s.
In 1965, hurricane Betsy hit New Orleans. The force by which it struck shocked the engineers down at the district. Therefore the district asked permission to the corps to heighten the structure by 1-2 feet. The corps agreed but shortly after the conformation, several complaints came to light originating from government officials, representatives of Congress and some local residents and interest groups. Some stated that the access to the lake could be hindered. Others complained about costs but the main arguments were environmentally tinted.
On the basis of court order, the district worked out an ‘Environmental Impact Statement’(EIS). After its formation, an advocacy group decided that the rules in the EIS did not correspond with those in the National Environmental Policy Act (NEPA). Affected by this statement, the District eventually constructed the ‘High level plan’ that was accepted by the director of civil works in 1985.
