Dredging projects inherently alter the natural environment to ensure that coastlines remain resilient, beaches are well-nourished and waterways are kept clear. Done in the traditional way, a dredging project can achieve its core service, but taking into account the concept of ecosystem services, the potential is there to add more.

Ecosystem services can be seen as either direct or indirect. Examples of direct forms of use relate to supporting goods such as wood, clean water and fish or to services such as recreational opportunities, and protection against flooding or climate change. Examples of indirect forms of use are nutrient recycling and fish nurseries, which result in direct services of clean water and fish production, respectively. Broadly speaking, both direct and indirect ecosystem services can be divided into the four categories in the box below.

Categories of ecosystem services

One of the more well-known ways of categorising ecosystem services comes from the Millennium Ecosystem Assessment. Their 2005 report, Ecosystems and Human Well-being, sets out the four types of ecosystem service – all of them relevant to dredging projects:

Provisioning Services – These are the products obtained from ecosystems, such as food, freshwater, timber, and raw materials.

Regulating Services – These services regulate ecosystem processes, such as climate regulation, flood control, water purification, and disease regulation.

Cultural Services – These include the non-material benefits people gain from ecosystems, such as recreational opportunities, aesthetic enjoyment, and spiritual value.

Supporting Services – These services support the processes necessary for the production of other ecosystem services, such as nutrient cycling or soil formation.

Incorporating ecosystem services: the framework

To approach the prospect of incorporating ecosystem services, the DFSI philosophy sets out a framework that should be followed when planning and executing a project.

The ecosystem services framework, at its core, bridges ecosystems to the socio-cultural context of human wellbeing and addresses the relationships between the two. Equally, the framework helps to analyse the impacts humans have on ecosystems and the feedback effects these changes have for the ecosystem benefits to humans.

A hands-on method, generally used as the starting point for the integrated assessment and evaluation of project benefits and impacts was proposed in the IADC Terra et Aqua journal in 2015.

1.  Identify the different habitat types that are affected by the project;

2.  Identify all ecosystem services delivered by those habitat types and select the relevant ecosystem services for the specific project;

3. Describe each ecosystem service as well as the underlying processes driving its delivery; and finally

4. Calculate the impact on all relevant ecosystem services in a quantitative and monetary way as much as possible.

Boersma, A., K. Van der Biest and P. Meire. 2015. Ecosystem Services: Towards integrated maritime infrastructure project assessments

Given the diverse nature of different ecosystem services, and the subsequent challenges posed in making calculations, each service generally has its own parameter (hence unit) that is used to enable quantification of effects. For instance, carbon sequestration is expressed in tonnes per hectare per year, while wood production is calculated as a volume (m3) per hectare per year. For monetary evaluation, these numbers need to be converted into financial figures (e.g. euro per year) in order to enable an objective comparison of project scenarios or design alternatives.

Non-use value of nature

Most of the ecosystem services are goods and services that can be used directly by people. The non-use value, however, has to be included in the overall balance as well. Not only because it is the right thing to do to protect nature as an intrinsic value, but also because we generate welfare from the protection of nature. We feel good by saving or developing nature, for example because these nature values remain available for next generations.

Precisely quantifying the non-use value of nature is, of course, impossible, so to get the best idea of that non-use value, the most productive thing to do is turn to public opinion. 

On example of this approach is the Contingent Valuation Method (CVM). In this method, carefully formulated survey queries are used to ask respondents how much they would be willing to pay for conservation of a natural, cultural or environmental element. This method is based on the ‘Willingness to Pay’ principle.

The principal benefit of including non-use values of nature in the evaluation assessment is that they become visible in the monetised overall cost-benefit analysis. In that way, they can play an important role in the acceptability of nature-based solutions for infrastructure projects.

In other cases, it is not appropriate to view the non-use value of nature through the lens of willingness to pay. For example, a dredging project may be proposed in an area that has intrinsic cultural value, meaning that the Public and Cultural Value Assessment method should be used. A dredging project may threaten a habitat that has cultural, historical, or symbolic value to local communities, so the non-use value should be assessed through public consultations or ethnographic studies that explore how these cultural and spiritual values are related to nature.

Ultimately, with the right long-term view, the involvement of stakeholders and appreciation of the eventual economic benefits derived from ecosystem services, sustainable dredging projects can become the norm.