Zoek binnen publicaties
Offshore wind farms as potential locations for flat oyster (Ostrea edulis) restoration in the Dutch North Sea
The “Dutch Energy Agreement” motivates governments and industries to invest in renewable energy sources, of which offshore wind energy is one of the solutions to meet the agreed target of 16% of the total energy budget from renewable resources by 2023. An option for the multi-use of wind farms is nature-inclusive building, in which the design and construction of wind farms make use of the potential for co-design with oyster bed restoration. This can support the government’s ambitions, for the Dutch North Sea, to achieve biodiversity goals, restore ecosystem functions, and enhance ecosystem services, including future seafood production. For the recovery of flat oyster (Ostrea edulis) beds, knowledge is required about the conditions under which active restoration of this species in the North Sea can be successfully implemented. This paper gives a framework and presents results to determine suitability of wind farms for flat oyster restoration, and provides recommendations for pilot studies. Our analysis showed that a number of wind farms in the Dutch section of the North Sea are suitable locations for development of flat oyster beds. Combining oyster restoration and oyster culture, as a protein source, is a viable option worth investigating.
Building with economic nature : market based instruments for risk management to promote spatial adaptation to climate change
Currently water management faces such challenges as high climate adaptation costs, scarcity of land, and low individual flood risk perception. This report reviews pros and cons of economic instruments (e.g. flood insurance, tradable development rights) that can be complementary to the structural defense measures in responding to these 3 challenges.
How ecological engineering can serve in coastal protection
Traditionally, protection of the coastal area from flooding is approached from an engineering perspective. This approach has often resulted in negative or unforeseen impacts on local ecology and is even known to impact surrounding ecosystems on larger scales. In this paper, the utilization of ecosystem engineering species for achieving civil-engineering objectives or the facilitation of multiple use of limited space in coastal protection is focused upon, either by using ecosystem engineering species that trap sediment and damp waves (oyster beds, mussel beds, willow floodplains and marram grass), or by adjusting hard substrates to enhance ecological functioning. Translating desired coastal protection functionality into designs that make use of the capability of appropriate ecosystem engineering species is, however, hampered by lack of a generic framework to decide which ecosystem engineering species or what type of hard-substrate adaptations may be used where and when. In this paper we review successful implementation of ecosystem engineering species in coastal protection for a sandy shore and propose a framework to select the appropriate measures based on the spatial and temporal scale of coastal protection, resulting in a dynamic interaction between engineering and ecology. Modeling and monitoring the bio-physical interactions is needed, as it allows to upscale successful implementations and predict otherwise unforeseen impacts.
Rich reefs in the North Sea : exploring the possibilities of promoting the establishment of natural reefs and colonisation of artificial hard substrate
This project, carried out on the instructions of the Ministry of Economic Affairs, is a preliminary study aiming to give an overview of possibilities and knowledge gaps pertaining to hard substrate in relation to ecological added value. It intends to provide input for the national policy on “Building with North Sea Nature”, which aims to bolster the conservation and sustainable use of species and habitats native to the Dutch section of the North Sea. As a result of various human activities, past and present, the North Sea is currently severely impoverished, not only in terms of the decline of species, but also in terms of loss of different types of habitat, in particular hard substrate.
A framework to include the (inter)dependencies of Disaster Risk Reduction measures in coastal risk assessment
Effective coastal risk management often involves the selection and appraisal of Disaster Risk Reduction (DRR) measures. Such measures, however, are rarely implemented in isolation and their (inter)dependencies need to be considered to assess the overall contribution to risk reduction. This paper presents a framework that utilises a pathway-based approach to consider such (inter)dependencies. The framework identifies measures that have the potential to directly influence risk reduction (primary measures) at the individual/household level and how these relate to the implementation of other measures (non-primary). These two types of measures are linked using intermediate pathway factors, which aggregate to the effective uptake and/or operation of primary measure(s) and subsequently represent the direct influence on risk reduction when included in a risk assessment. The approach is demonstrated utilising two coastal risk examples. The case of Varna Bay, Bulgaria highlights a pathway, which explores how developing a coastal Early Warning System (EWS), can enable assets to be moved and saved prior to an event. The Praia de Faro, Portuguese application provides an example of how local risk awareness meetings can support the uptake of property raising to protect against erosion. Past experience, poor trust in authorities, house type/feasibility, transient population and strong community networks are identified as key influencing variables across both cases. The process of considering the (inter)dependencies between measures has potential to lead to improved decisionmaking and strategy building. The framework developed is flexible in nature and can be applied in many different situations; however, it is one step towards accounting for these (inter)dependencies at the individual/household level. Ex-ante or ex-post survey data, expert judgement and literature have been used to estimate these factors. However, in many cases this good quality data is not available, and is something that national level monitoring strategies, along with the research community, must address.
Beneficial use of dredged sediment to enhance salt marsh development by applying a ‘Mud Motor’
We test an innovative approach to beneficially re-use dredged sediment to enhance salt marsh development. A Mud Motor is a dredged sediment disposal in the form of a semi-continuous source of mud in a shallow tidal channel allowing natural processes to disperse the sediment to nearby mudflats and salt marshes. We describe the various steps in the design of a Mud Motor pilot: numerical simulations with a sediment transport model to explore suitable disposal locations, a tracer experiment to measure the transport fate of disposed mud, assessment of the legal requirements, and detailing the planning and technical feasibility. An extensive monitoring and research programme was designed to measure sediment transport rates and the response of intertidal mudflats and salt marshes to an increased sediment load. Measurements include the sediment transport in the tidal channel and on the shallow mudflats, the vertical accretion of intertidal mudflats and salt marsh, and the salt marsh vegetation cover and composition. In the Mud Motor pilot a total of 470,516m3 of fine grained sediment (D50 of ∼10 μm) was disposed over two winter seasons, with an average of 22 sediment disposals per week of operation. Ship-based measurements revealed a periodic vertical salinity stratification that is inverted compared to a classical estuary and that is working against the asymmetric flood-dominated transport direction. Field measurements on the intertidal mudflats showed that the functioning of the Mud Motor, i.e. the successful increased mud transport toward the salt marsh, is significantly dependent on wind and wave forcing. Accretion measurements showed relatively large changes in surface elevation due to deposition and erosion of layers of watery mud with a thickness of up to 10 cm on a time scale of days. The measurements indicate notably higher sediment dynamics during periods of Mud Motor disposal. The salt marsh demonstrated significant vertical accretion though this has not yet led to horizontal expansion because there was more hydrodynamic stress than foreseen. In carrying out the pilot we learned that the feasibility of a Mud Motor depends on an assessment of additional travel time for the dredger, the effectiveness on salt marsh growth, reduced dredging volumes in a port, and many other practical issues. Our improved understanding on the transport processes in the channel and on the mudflats and salt marsh yields design lessons and guiding principles for future applications of sediment management in salt marsh development that include a Mud Motor approach.
Annual review Deltares 2012
The usability of the sand motor concept
This report describes the usability of the Sand Motor concept for managing the Dutch coast as an alternative to regular sand nourishments. The evaluation of the usability is based on experience with the Sand Motor pilot project before, during and after the construction in 2011 and by making an inventory of the functions and values along the Dutch coast in the present situation and the coming decades.
Annual review Deltares 2011
Adaptive water management for delta regions : towards GREEN Water Defense in East Asia
GREEN Water Defense is an innovation to traditional ways of flood protection. It uses ecosystem services to mitigate the flood hazard. The report describes best practices from the Netherlands, the USA and other OECD countries The report also identified good opportunities for applying the concept in the Mekong Delta, Vietnam and the Jakarta metropolitan area, Indonesia.