Combined approach (grey + green)

A breakwater is a coastal structure (usually a rock and rubble mound structure) projecting into the sea that shelters vessels from waves and currents, prevents siltation of a navigation channel, protects a shore area or prevents thermal mixing (e.g. cooling water intakes). A breakwater typically comprises various stone layers and is typically armoured with large armour stone or concrete armour units (an exception are e.g. vertical (caisson) breakwaters). A breakwater can be built at the shoreline or offshore (detached or reef breakwater). This measure is not directly addressed to protect the coast in flood events, but can indirectly stabilize the coast by preventing erosion.

River restoration contributes to flood risk management by supporting the natural capacity of rivers to retain water. As flood risk consists of damage times occurrence, flood risk management needs to reduce either the damage, or the likelihood of floods to occur, or both. River restoration reduces the likelihood of high water levels, and improves the natural functions of the river at same time.

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

Near to the RISC-KIT Case Study in Emilia – Romagna, a LIFE+ “LIFE RINASCE” project has been implemented in 2014 to improve some of Emilia - Romagna drainage channels in the Po floodplain. Project leader is the Emilia Centrale Land Reclamation Consortium, in collaboration with the Emilia -Romagna Region. The project was started in 2014 and will run the end of 2018 with a total budget of almost 2.1 million €.

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.

By 2002, historic Clavell Tower was deemed to be at serious risk of collapsing under the crumbling Dorset coastline at its base. The most technically, socially, and financially feasible solution was to simply dismantle the empty tower and reconstruct it further away from the cliff’s edge on more stable footing. This resulted in a reinvigorated heritage site saved from the dangers of coastal erosion.

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.

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.

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.

The beach of Pevensey Bay (UK) is a shingle barrier beach under threat from flooding and coastal erosion. Today, the beach is managed in an adaptive manner developed by Pevensey Coastal Defence, where management activities respond to changes in risk and beach recharge and beach recycling is undertaken.

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.

The case study shows how sand replenishment at the west coast of Denmark has become the main measure to face coastal erosion. Experiences in the last years showed, that replenishments at the foreshore seem to be the most effective and ecosystem friendly version of beach nourishments.

When rivers are denied the space to meander due to levees, rock revetments, or other impediments, many beneficial river services are diminished. Setback levees increase channel capacity for carrying floodwaters. Once a levee is setback, the river may begin to meander and this poses a challenge to implementing riparian restoration on the floodplain.

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.

Cliff stabilization is a coastal management erosion control technique. Generally speaking, the cliffs are stabilised through anchoring (the use of terracing, planting, wiring or concrete supports to hold cliffs in place), smothing the slope, or dewatering (drainage of excess rainwater to reduce water-logging).

Shingle beaches are mobile structures developed in high-energy environments that are very efficient at absorbing and dissipating wave energy. Restoration of shingle beaches on the foreshore can create a more desirable morphological profile that is better able to dissipate wave energy and attenuate storm surge.

In the RISC-KIT Case Study area of Emilia-Romagna (Italy), a study has been undertaken to gain insights about improvements of the design of beach scraping operations. Here, a numerical modeling approach was used to find more appropriate beach scraping design.

Soils face various risks related to erosion and pollution, however, adopting good land and soil management practices can help mitigate these negative impacts and in some cases can improve the overall productivity of soils. Such practices generally seek to improve soil structure and/or increase cover so as to reduce erosion, increase soil infiltration, and reduce runoff and transport of sediments. 

Managed realignment is a measure that usually results in the creation of a salt marsh by removing costal protection an allowing for an area previously protected from flooding to become flooded. Managed realignment is a measure dealing with sea level rise and coastal erosion. It is also often a method that replaces hard coastal defense measures with soft coastal landforms. Rather than relying on hard structures for defense, managed realignment depends on natural defenses to absorb or dissipate the force of waves.

To reduce cliff erosion and its consequences – landslide, collapse, falling of rocks – cliff strengthening techniques aim at increasing the strength and overall stability of the slope by minimizing landside pressures.

A breakwater is a coastal structure (usually a rock and rubble mound structure) projecting into the sea that shelters vessels from waves and currents, prevents siltation of a navigation channel, protects a shore area or prevents thermal mixing (e.g. cooling water intakes). A breakwater typically comprises various stone layers and is typically armoured with large armour stone or concrete armour units (an exception are e.g. vertical (caisson) breakwaters). A breakwater can be built at the shoreline or offshore (detached or reef breakwater). This measure is not directly addressed to protect the coast in flood events, but can indirectly stabilize the coast by preventing erosion.

Beach drains comprise perforated land drain pipes buried below the upper beach surface, and connected to a pump and discharge. The concept is based on the principle that sand will tend to accrete if the beach surface is permeable due to an artificially lowered water table. The system is largely buried and therefore has no visual impact.

The construction of floodwalls and embankments has been the traditional means of protecting lowlying communities and infrastructure against flooding. Although the primary function of a wall or embankment may be flood defence, such structures also frequently have a secondary function – quite often with the aim of enhancing the environment or improving the amenity or both.

Dredging is the general term used for the excavation of material below water level either as a maintenance activity or as part of channel enlargement works. The main purpose of dredging is either to maintain the navigation depth or the flood capacity, or sometimes both.

Lowland rivers and estuaries are naturally often flanked by vast areas of floodplain that was periodically flooded. The extent of inundation varied between years and formed an integrated system together with the river for moving water from the continental interiors to the ocean. With settlements and farming activities in these floodplain areas, these areas were disconnected to the river system.

With the idea of flood bypasses, these portions of the historic floodplain are reconnected to the river and become inundated during major flood events. They act as relief valves in two ways: conveyance and storage. If this attempt is used in area were these bypasses are not based on historic floodplains, the term relief channels is used.

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.

Bank protection is needed where there is the risk of erosion of the bank and where this erosion would cause economic or environmental loss. If there is sufficient space available, it may be possible to reduce the need for bank protection by re-profiling the bank to a flatter slope to reduce velocities and encourage good vegetation growth. Even if bank protection is still required, it may be less severe if a flatter slope can be achieved, or may only be required below normal water level.

Traditionally, interventions in river channels have been carried out to reduce flood risk at a particular location. This approach has produced artificial river geometries which have often been found, for a variety of reasons, to be unsustainable. A core principle of modern river engineering is that, in general terms, rivers tend to return to their natural ‘regime’ state, in which the main channel has the capacity for a particular flow and no more.

If fluvial systems don't have sufficient room for natural detention of floodwater in the floodplain, the development and management of flood storage within and adjacent to the natural floodplain is recommended and described in more detail in this measure. It addresses aspects like the process of selecting where to locate the flood storage, deciding how much storage is needed, how to measure the storage capacity, selecting appropriate flow control structures, analysing how the works will perform and making sure that the flood storage scheme is safe in extreme floods.

For the rehabilitation of a dune system, an elevated wooden pathway over the shore and the dunes and a dune fence were created. They were created to restore the physical and ecologic characteristics of the dunes at a natural Park at Praia de Faro (Portugal). The cost effectiveness is analyzed in this description and compared to beach nourishment.

Sand dunes are wind forms elements on sandy coasts and represent a natural coastal protection measure. Natural processes like erosion and human interference (like coastal protection measures, changing coastal processes, tourism) can have a negative impact on dunes. Rehabilitation with feeding sand or planting vegetation can reinforce the dunes.

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.

A new form of beach nourishment is the 'Zandmotor' (sand-motor) undertaken in the Netherlands. Instead of having smaller nourishments in a time period of 4 to 5 years, the water authority Rijkswaterstaat formed 21.5 million m3 of sand into a peninsula near Ter Heijde in 2011. In the beginning, the peninsula stretched 1 km into the sea and was about 2km wide. The idea is that waves, current and wind spread the sand along the coast and thus enhance the coastal protection and at the same time create a dynamic natural and recreational area. It was expected to have a repeating interval of only 15-30 years.

Beach nourishment describes a measure where sediment that is lost due to longshore drift or erosion on a beach is replaced from material outside of the eroding beach. This results in a wider beach that can reduce storm damages and coastal erosion. Beach nourishment is typically a repetitive measure, since it does not remove the physical forces causing erosion, but is a measure that mitigates the effects of erosion.

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. 

Beach scraping is recovering material from the berm at the foreshore and placing it on the backshore at the foot of the dunes or the cliff.