Coastal towns

Not all stakeholders are aware or informed about their vulnerability to a changing climate, or flood risk protection. Nor are they aware of the pro-active measures they can take to adapt or deal with climate change. Awareness raising and education programs are therefore important to manage the impacts of climate change, enhance peoples’ capacity to deal with the impacts, and reduce overall vulnerability.

Sharing knowledge in this way can help build safety and resilience, reduce future hazard impacts. Communities and individuals usually want to become partners in this, and the public can be empowered to deal with the impacts and reduce future problems related to flood risk and disaster risk response.

In Finland urban wetlands are being implemented to help improve water quality, absorb storm water volume and flow control, and improve the land-water habitats for urban communities. The wetlands are designed to respond to the needs and negative impacts of urbanization and therefore, public acceptance and multifunctional benefits are central to the design and implementation of the wetlands. The acceptance and understanding of the importance of urban dwellers is important and thus the project sought to demonstrate several benefits of functional wetlands.

The main objective of land claim is neither erosion nor storm reduction.  The aim of land claim is to create new land from areas that were previously below high tide.  These measures can be taken to reduce the exposure of these areas to coastal flooding.  For example, in Singapore and Hong Kong, there are enforced minimum reclamation levels to account for future sea level rise

Venice, Italy, is a city famous around the world for not only its stunning canals and historic buildings, but also for its high vulnerability to flooding. The MOSE system of mobile flood barriers is a bold initiative intended reduce risk, preserve the cherished cityscape, and protect the entire Venice Lagoon from flooding.

Augustenborg is a highly populated neighbourhood in Malmö, Sweden. In order to minimise flood risk, between 1998 and 2002, the ‘Ekostaden Augustenborg’ initiative installed a ‘Sustainable Urban Drainage System’ (SuDS). As part of the project, green roofs, ditches, retention ponds, green spaces and wetlands were created. Due to the installation of the SuDS, rainwater run-off has decreased by half.

The county of Sogn og Fjordane frequently experiences avalanches and landslides, storm surges and flooding. A demonstration project explored the potential for an effective, reliable and cost-efficient early warning system that has a multi-hazard approach and makes use of location and population-based communication technologies, such as mobile phones, as well as social media such as Facebook and Twitter. The system was tested with a sample warning followed by a survey and data analysis to judge its efficacy.

As in many other cities, the former dominating strategy for Oslo’s rivers and streams was to enclose them for practical reasons. This approach has changed and the City is actively reopening waterways to make them accessible for people, facilitate increased habitat for biodiversity and handle storm water more efficiently.

In 2014, the London Resilience Partnership developed the second Mass Evacuation Framework for the city of London. The purpose of this Framework is to offer guidance to responders managing a mass evacuation of displaced persons and, where appropriate, other living creatures.

The Framework has been developed by the Multi-Agency London Resilience Partnership Mass Evacuation Group. This group consists for example of the City of London Police, London Fire Brigade Emergency Planning, Environment Agency, Ministry of Defence (London), or Network Rail.

Cascais is a Portuguese city on the Atlantic coast and 30 km west of Lisbon. Within the project BASE, researcher supported the participatory ICZM approach to develop a Climate Adaptation Action Plan.

On the island of Kauai, Hawaii in the USA, the local governing county has implemented flexible and protective coastal setbacks that protect communities from coastal erosion and avoid shoreline armouring in the long term.

Criel sur Mer is a small town in Normandy in the region of Northern France, known for its stunning coastline of steep chalk cliffs. Erosion of the cliffs in Criel sur Mer is occurring rapidly as a result of climate change but also due to man-made construction works further up the coast. In Criel sur Mer a short piece of land on the coast that is eroding rapidly and several homes built near the sea are threatened by the predicted collapse of the cliff. In particular, a street of homes were faced with immediate danger from erosion. Between 1995 and 2003, the local administration organized the abandonment and demolishment of 14 homes due to imminent risk from natural disaster under the Barnier Law. The adoptive policy was to do nothing against cliff erosion and to demolish and relocate those in immediate threat and compensate them fairly for their lost property.

The Clacton to Holland-on-Sea (UK) stretch of coastline has suffered from significant sediment loss, which negatively impacts the local community and economy. Collectively, five kilometres of beach are at risk of washing away including nearby tourism promenades and over 3000 homes and businesses. In response, a major sea defence project is underway to fortify the coast through construction of new rock groynes and beach nourishment activities. It is expected that this project will reduce coastal erosion for the next 100 years.

The Ventura County Chapter of the Surfrider Foundation in California, USA decided against traditional coastal defence measures to reduce beach erosion at a popular beach spot called Surfer’s Point. Along with other stakeholders, the County instead designed a two-phase plan to strategically relocate a parking lot, pedestrian path, and bike path away from erosion zones.

In 1996 the Dutch Department of Transport, Public Works and Water developed a program called ‘Roads to the Future,’ and a component of this project was the testing of a pilot floating road. The testing of the pilot took place in 2003 and aimed to create a 70 meter stretch of road in the town of Hedel, the Netherlands to mitigate against rising ground water levels. The floating road was designed to maintain access and flexibility in traffic and movement and prevent the isolation of a village otherwise cut off by flooding.

An informative brochure can help raise awareness for coastal residents to inform about climate related risks and offer behavioural recommendation. For the city of Kiel such comprehensive guideline was developed.

Construction of the first components of the Wroclaw floodway system in Poland, one of the largest flood protection systems in Europe started in 2011. The project includes large scale improvements to the system of river channels and flood defenses which provide protection from the floodwaters of the River Odra that flows through Wroclaw. The goal of the project is to reduce the city’s flood risk to a probability of less than a 1000-year event.

Amager Beach is a constructed island in the southern part of Copenhagen. It was built between 2004 and 2005. It not only serves recreational purposes for the local population, but is also a coastal defense structure to protect the main coastline. This artificial approach is a very good example of combining ecosystem based approaches with coastal defense aspects.

Water harvesting is when rainwater or stormwater is collected and stored for productive use later. It can be used for agriculture, drinking and more. Historically, rainwater harvesting is a common practice and has been used by many communities to support agriculture in sensitive and variable climates.

Coastal and marine environments are usually characterized by beautiful landscapes and rich ecosystems of great importance, offering elements such as rich biodiversity. They also attract human activities such as tourism and industrial uses. However, the co-existence of human activities and natural resources often creates conflicts of use in the coastal zone.

Management policies are an important means of implementing planning in order to minimise, prevent or resolve use conflicts. The development of a coastal and marine spatial planning system presents an opportunity for the implementation of an overall strategy of conservation, sustainability and management to maximise future economic profit.

Flood forecasting is an essential tool for providing people still exposed to risk with advance notice of flooding, in an effort to save life and property.

To minimize the loss of lives and reduce other flood impacts, an area should be evacuated when the depth of standing water due to flooding is already or is expected to become high. Such floods are defined as those which are expected to cause buildings, including residential houses, to be washed away or seriously damaged by the flooding.

The purpose of early warning systems (EWS) is simple. They exist to give advance notice of an impending flood, allowing emergency plans to be put into action. EWS, when used appropriately, can save lives and reduce other adverse impacts.

It is vital to recognize that even after the implementation of non-structural flood mitigation measures residual flood risk will remain. It is of paramount importance to make plans to deal with flood events and their aftermath. This involves multiple activities which can be included as part of a flood emergency plan. In this section there is an overview of the elements central to emergency planning.

An urban flood event requires immediate measures to ensure that citizens have safe drinking water, including appropriate excreta disposal, disease vector control and waste management. However, during and after a flood event is not necessarily the best time to communicate health messages to individuals and organizations, as they may be dispersed and not have access to the necessary resources. Health Awareness Campaigns are vital ‘soft’ interventions alongside hardware provision (waste water treatment, for example); together they can help preserve public health by increasing preparedness. Health awareness and hygiene promotion campaigns must not be carried out independently from water supply and sanitation, and vice versa.

Flood risk awareness is the cornerstone of non-structural flood risk management. All actions to minimize the impact of flooding hinge upon stakeholders becoming aware these are both necessary and desirable. Ignorance of flood risk encourages occupation of the floodplain, in the first instance, and can allow appropriate building design practices to fall into disuse. In the event of a flood, the lack of awareness of risk can result in a failure to heed warnings to evacuate, thereby endangering lives.

Approaches to manage surface water that take account of water quantity (flooding), water quality (pollution) biodiversity (wildlife and plants) and amenity are collectively referred to as Sustainable Urban Drainage Systems (SUDS). Such drainage systems not only help in preventing floods, but also improve water quality. In addition they can enhance the physical environment and wildlife habitats in urban areas.

A sea dike is a manmade structure designed to protect low-lying areas from flooding from the sea or ocean. They typically are designed with several components including a sand core, a watertight outer protective layer, toe protection and a drainage channel. Sea dikes are intended to withstand and resist water and wave action. They are widely used in countries with low lying geographies such as Vietnam, Bangladesh, Thailand, the Netherlands and parts of the United States.

Surge barriers and closure dams are protective measures designed to prevent a storm or high tide from flooding an area. A surge barrier is often a movable structure that is signaled to close prior to a storm and reopen to facilitate transport of goods and boats or if protecting an estuary, to allow natural movement of tides. A closure dam on the other hand is a permanent structure. Both are significant physical barriers that require advanced civil engineering and substantial construction. They provide a physical barrier and are used to protect coastal communities, tidal inlets, rivers and estuaries from extreme weather events.

Dikes and dams need regular maintenance and strengthening to keep their protection capacities and meet safety requirements. In addition, climate scenarios for sea level rise and extreme weather conditions can lead to reconsidering safety requirements and building new protections on identified weak points or heightening and strengthening existing ones. The design of existing dikes and dams can be modified to fulfill different purposes.

A temporary flood barrier is one that is only installed when the need arises (that is, when high flood levels are forecast). A demountable flood defence is a particular form of temporary defence that requires built-in parts and therefore can only be deployed in one specific location. The removable stoplog defence is a particular form of demountable defence applicable only for small openings in a permanent defence. The more commonly adopted gate option for closing off a gap in a floodwall is neither temporary nor demountable, as it is part of the permanent defence and is left in place all the time (albeit normally in an open position).

Culverts typically carry flow in a natural stream or urban drainage channel under a road or railway. In some urban areas, the practice of culverting long lengths of a natural watercourse to gain space for urban development has traditionally been widespread. The practice is now generally recognized as having a negative impact on amenity and biodiversity. By reopening the culverts, these negative impacts can be reduced. In this way, the re-opened culverts can help manage stormwater and slowing down the flow of stormwater.

Urban drainage systems need to be able to deal with both wastewater and stormwater whilst minimizing problems to human life and the environment, including flooding. Urbanization has a significant effect on the impact of drainage flows on the environment: for example, where rain falls on impermeable artificial surfaces and is drained by a system of pipes, it passes much more rapidly to the receiving water body than it would have done when the catchment was in a natural state. This causes a more rapid build-up of flows and higher peaks, increasing the risk of flooding (and pollution) in the receiving water. Many urban drainage systems simply move a local flooding problem to another location and may increase the problem. In many developed counties there is a move away from piped systems, towards more natural systems for draining stormwater.

A seawall or a revetment is a structure made of concrete, masonry or sheet piles, built parallel to the shore at the transition between the beach and the mainland or dune, to protect the inland area against wave action and prevent coastal erosion. Seawalls are usually massive structures designed to resist storm surges.

'Elevation of buildings' and ' Land raising' are two separated measures with the aim to elevate exposed elements.

Moving a building out of the existing flood hazard area is the safest solution among several retrofit-ting methods; however it is also usually the most expensive method (FEMA, 2009). When a community acquires a flood-prone home from the owner, relocation is often applied, as well as demolition of the building. The relocation is not only limited to buildings, it can also be applied to other exposed coastal infrastructure.

Dryproofing makes a building watertight and substantially impermeable to floodwaters (FEMA, 1993). Compared to wetproofing, dryproofing requires a more reinforced building structure to withstand floodwater pressures and impact forces caused by debris. Other important factors to be considered in dryproofing are watertight closures for doors and windows, prevention of floodwater seepage through walls, and check valves to prevent reverse flows from sewage.

Wetproofing (or wet floodproofing) is different from dryproofing in that it allows flood water to enter a structure, though both floodproofing methods have the same purpose, that of preventing damage to the structure and its contents and creating no additional threats to public safety (FEMA, 1993).

Highly dynamic coastal systems (like sandy beaches, dunes or estuaries) might be best managed by not interfering with the natural processes, but instead accepting that change will occur and adapting backshore management accordingly. Key in this approach is a proper monitoring of the processes to analyze and evaluate the changes (for examples at eroding cliffs or dunes). With a proper planning horizon, these changes can be anticipated and with enough room for the environment to involve this can be a very cost-extensive approach.

Artificial reefs are shore parallel rock mound structures set part way down the beach face. They may be long single structures or form a series of reefs extending for some distance alongshore. They are submerged for at least part of the tidal cycle, and are therefore less intrusive on the coastal landscape, have less impact on upper beach longshore processes and add a new intertidal habitat to sandy foreshores.

The municipality of Timmendorfer Strand developed and implemented a coastal protection strategy using a participatory process. This process was a key element for the successful implementation of the measure. Although this measure was very expensive, a cost-benefit analysis shows that the benefits are higher than costs.