Building with Nature BwN Guideline Environments Project phases Governance BwN Knowledge base
BwN Building Blocks BwN Toolbox Pilots and cases BwN Knowledge

Log in

The CUMULEO-RAM model, where CUMULEO is the name of the collection of cumulative models within IMARES and RAM stands for Risk Assessment for the Marine environment (Karman & Schobben 1995, Schobben et al. 1996, Jak et al. 2000, Karman et al. 2001), has been developed by IMARES (de Vries et al., 2011a&b). It is a methodology to quantify cumulated effects of human activities on the marine environment. The tool is unique in that it uses species-specific exposure-effect relationships to quantify and integrate potential effects. In theory, the method may be used to identify where, when and how an activity contributes to an effect. The potential applicability of the method for the dredging industry is presented and discussed below.

The tool was developed with the aim to assist government and industry in identifying emissions with the highest impact to the environment, in order to prioritise possible emission reduction technologies. Application of the tool requires assistance of IMARES.

    General Tool Description

    Before going into a detailed description, it should be mentioned that this model is still conceptual. Nonetheless, a description is given here, as this is considered a tool with high potential.

    Context purpose and results

    When attempting to manage marine activities in a sustainable manner, knowledge of the relation between the impact of these activities and the state of the marine environment is crucial. The CEA (Cumulative Effect Assessment) model “CUMULEO-RAM” focuses on relationships between activities and pressures, and between pressures and population effects, the latter expressed as the net reproduction rate. Each of these relationships can be quantified via intensity variables varying in time and space. In the case of pressures and species, for instance, this yields quantitative exposure-response relationships.

    Causal relationships between exposure level and effect level for individual species are also used in other tools described in the Building with Nature Knowledge Base: Species Sensitivity Distribution (SSD) and cause-effect chain modeling. The present model is unique in that it uses species-specific exposure-effect relationships to quantify and integrate potential effects. It can be used as a (spatial) tool to manage human activities, ensuring that the collective pressure of maritime activities is kept within acceptable bounds.

    The basic approach of CEA (Cumulative Effect Assessment) is the assumption that effects can be expressed as functions of the intensity of the exerted pressures and the sensitivity of the relevant ecosystem components to those pressures (Figure 1).There are two phases one needs to go through, viz. the scoping phase and the assessment phase. In the scoping phase one defines spatial and temporal boundaries, identifies ecosystem components of concern, pressures and activities, and establishes how these are linked, including exposure-effect relationships. In the assessment phase the intensity of activities and pressures is described and assessed, as well as the sensitivity of ecosystem components and effects. For further details, see the section ‘How to use’.

    The model is a good tool to express impacts of activities in terms of population-relevant indicators and to compare activities by their relative impact. Ranking activities according to their relative impact makes it possible to guide measures to the most harmful activity in a transparent manner. Transparency of approaches makes management plans easier to accept.

    Usage skills

    Implementation of the prototype CUMULEO-RAM model in a case study of the Wadden Sea and the North Sea coastal zone of the Netherlands is briefly described in the ‘practical applications’ section and elaborated in de Vries et al. (2011a). In order to make the model applicable for the marine construction industry, it needs to be adjusted to the specific activities and pressures at hand. This requires a complete scoping and assessment phase, to be carried out by IMARES, developer of the model. Typical results of CUMULEO-RAM are maps showing the intensities of pressures or effects, pie charts showing the relative contribution of pressures (or activities) to the cumulated effect, column charts showing the potential cumulated effect for different scenarios, etc.

    BwN interest

    It is possible to use CUMULEO-RAM in all phases of a project, but ideally it should already be applied in an early stage: the initiation or planning and design phase. A thorough understanding of the system is vital to the design process. Knowledge of the potential effects (intensity and extent) of the proposed activities on the environment is essential. By comparing the potential effects of different design alternatives, the project design can be optimised to reduce environmental impacts and/or to optimise positive effects. Application of CUMULEO-RAM will benefit this process and enables broad scoping. It may help achieving the BwN goal “scoping goes beyond sectoral interests and limited problem perceptions, focusing on opportunities and win-win solutions”. In the construction phase it is important to apply adaptive construction methods to manage direct (and if possible indirect) effects, to involve stakeholders, to provide transparent information, and to be receptive to suggestions. Because CUMULEO-RAM helps identifying the activities with the strongest effects and is easily adjusted to specific conditions, it is a very useful tool in the construction phase.

    During the operation and maintenance phase it is important to inform the public, and other stakeholders, about the life-time development of the project, especially regarding environmental issues. 
    The visual presentation of results, combined with the speed of the calculations makes it a powerful tool to support discussions with experts, stakeholders and policymakers. Thus, applying CUMULEO-RAM from the early project phases on will benefit the whole project (see Figure 2).

    How to Use

    Phased plan process

    When applying the tool in a specific project one needs to go through two stages: the first will be done in cooperation with IMARES (A), the second can be executed by the user him-/herself (B).

    A) Scoping and assessment phase. Initially, these two phases are carried out by IMARES.

    1. Scoping phase
    • Define spatial and temporal boundaries
    • Identify ecosystem components of concern, pressures and activities, and establish the relationships between them
    1. Assessment phase
    • Determine intensity of activities
    • Determine intensity of pressures, related to the intensity of activities
    • Determine sensitivity of ecosystem components to the different pressures
    • Determine cumulated effects, related to the intensity of pressures

    B) When this is ready for use in its specific project context, four steps need to be taken by the users to identify the activities with the highest impact (positive or negative) on the environment, in order to prioritise possible management options. This can be achieved by taking the four steps mentioned below, to be further explained by IMARES when the tool will be applied in the specific project:

    1. Calculating the ecological impact/effect of current or proposed activities with use of this tool (benchmark);
    2. Ranking pressures by their impact/effect;
    3. Identifying options to adjust the activities;
    4. Evaluate changes in impact/effect due to the adjusted activities.
    Model development perspective

    The current and future possibilities of this model, as briefly described in this section, contribute to a science-based, tailor-made control and surveillance process that will allow the adaptive and cost effective management of marine construction operations:

    • Science-based: The model is based on specific exposure-response relationships described by Jak et al. (2000) and Karman et al. (2009).
    • Tailor-made: This general approach to CEA can be adjusted according to: required (management) purposes; site specific conditions; proposed activities; etc.
    • Control and surveillance process: The model in its current design is not intended to provide ‘real time’ results of marine construction activities. Instead, it calculates potential intensities of pressures, impacts and effects resulting from proposed activities.
    • Allow the adaptive and cost effective management of marine construction operations: The model enables adaptive management of marine construction operations as the intensities of pressures, impacts and effects resulting from different marine construction scenarios can be easily calculated. The proposed activities can thus be adjusted as to minimise potential effects. This model does not include socio-economics, but it does have the potential to include such elements. For example, by including the costs as a pressure, the total costs per scenario could be calculated, therewith showing cost-effectiveness of mitigation measures.

    Recommendations and advice

    In a BwN marine construction project one needs to take into account some specific pressures in the assessment:

    • Exposure to increased concentrations of suspended matter in the water column (turbidity) and exposure to the deposition of a layer of sediment with a thickness > 20 cm (burial);
    • Extraction of species (extraction of benthic species by marine construction and dredging);
    • Change in substrate (permanent change in substrate, e.g. from hard to soft, or from soft to hard; also: creation of new substrate, e.g. offshore structures);
    • Acoustic disturbance (exposure to continuous noise) and;
    • Visual disturbance (presence of humans; boats; and constructions).

    Most of these pressures are already included in the CUMULEO-RAM model. Adjustments to the model are required in order to specifically address all relevant pressures.

    Practical Applications

    Potential application for the marine construction industry

    CUMULEO-RAM has not yet been applied in a BwN (related) project, but the model has been described and demonstrated in a case study of the Wadden Sea and the adjacent North Sea coastal zone (de Vries et al., 2011a).

    Scoping

    In Figure 3 an example of the CEA for dredging activities is presented as applied in the demonstration. As shown in the figure, all dredging activities lead to emissions of sound (noise) and most activities lead to increased suspended sediments and deposited material. The links (relationships) are also determined.

    Assessment

    The four steps mentioned in the “How to use” section, when the model is ready for use in its specific project context, are illustrated here:

    1. Calculating the ecological impact/effect of current or proposed activities with use of this tool (benchmark).
      For demonstration purposes some results are shown where the tool was used on the response of representative species in the Wadden Sea ecosystem to current and future shipping activities. Audio-visual disturbance, toxicity, and turbidity were identified as pressures. Several bird species, marine mammals, fish and benthos species were selected as ecosystem components. Potential effects on biota were expressed as “one minus the net reproduction rate”, which is defined as: “the number of adult individuals that are expected to be produced by a just matured juvenile during its entire adult life stage”. In an undisturbed situation, the reproductive rate is assumed to be 1 (representing a stable population). The parameters are calibrated such that the parameter values are as close to their modes as possible but with the resulting reproductive rate near 1.Simply stated, the potential effect ranges from 0 up to 1. When equal to 0, the population is not affected, whereas when equal to 1, the population is maximally affected. The potential effect is calculated for both a present and a future situation, making it possible to calculate the effectiveness of design specifications.
      The absolute potential effects calculated for the ecosystem components (biota) were marginal (no more than 0.04 on a scale of 0 to 1) and mainly due to audio-visual disturbance (i.e., presence in the area) (Figure 4). This absolute level is based on worst-case assumptions and should be seen as indicative.

    2. Ranking pressures by their impact/effect;
      As is shortly mentioned in ‘How to use’, it is also possible to include a spatial dimension in the CEA. Figure 6 shows an example of potential effects of activities in the Wadden Sea. Potential effects on biota were expressed as “one minus the net reproductive rate”.
    3. Identifying options to adjust the activities;
      Application of CUMULEO-RAM shows which activity will cause the largest intensity/pressure in a certain area. It also shows the relative sensitivity of the selected ecosystem components to the pressures. This provides additional insight because the extent to which pressure leads to effect depends on the sensitivity of the species. For instance, it could be that the activity causing the largest pressure has only a small contribution to the cumulated effect on a certain species, because the species is relatively insensitive to this pressure. CUMULEO-RAM provides insight into these relations.
    4. Evaluate changes in impact/effect due to the adjusted activities.
      CUMULEO-RAM can be applied for different scenarios, allowing to evaluate changes in impact and/or effects due to proposed activities.

    The absolute potential effects calculated for the ecosystem components (biota) were marginal (no more than 0.04 on a scale of 0 to 1) and mainly due to audio-visual disturbance (i.e., presence in the area) (Figure 4).

    This absolute level is based on worst-case assumptions and should be seen as indicative. The model also allows presenting the relative contribution of the pressures to the overall effect, for an example see figure 5.

    As is shortly mentioned in ‘How to use’, it is also possible to include a spatial dimension in the CEA. Figure 6 shows an example of potential effects of activities in the Wadden Sea. Potential effects on biota were expressed as “one minus the net reproductive rate”.

    Application of CUMULEO-RAM shows which activity will cause the largest intensity/pressure in a certain area. It also shows the relative sensitivity of the selected ecosystem components to the pressures. This provides additional insight because pressure does not automatically lead to effect; this depends on the sensitivity of the species. For instance, it could be that the activity causing the largest pressure has only a small contribution to effects on survival of a certain species because the species is relatively insensitive for this pressure. CUMULEO-RAM provides insight in these relations.

    References

    Suggestion for further reading

    Back to Top