Predicting ecotopes for the assessment of nature-based solutions. A case study on the Western Scheldt
Brunink, S. (2022). Predicting ecotopes for the assessment of nature-based solutions. A case study on the Western Scheldt. MSc Thesis. Delft University of Technology: Delft. vi, 63 pp.
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Documenttype: Doctoraat/Thesis/Eindwerk
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| Abstract |
Nature-based Solutions (NbS) have recently gained more interest in hydraulic engineering. It is based on the concept of using forces of nature rather than working against them. In addition, it focuses on using natural processes to fulfil co-benefits for the parties involved.One of the parties involved is nature. However, a quantitative analysis of ecological development is necessary to determine possible co-benefits for nature. This is still found challenging due to the dependency on many variables, the difference in spatial and temporal scales, the limitations in available information, and the non-linearity.Ecological development can be expressed with ecotopes, linking geomorphological and hydrological characteristics to abiotic characteristics. A Dutch Ecotope System for Coastal Waters (ZES.1) is a classification system of Rijkswaterstaat. It is a hierarchical system based on abiotic characteristics that classify ecotopes based on thresholds that are determined by ecological differences.In this thesis, the Ecotope Map Maker based on Abiotic characteristics (EMMA), is developed. It uses data from a validated hydrodynamic model as input and subsequently maps ecotopes based on the ZES.1. Ecotope labels are composed by combining labels that are given to values of salinity, inundation, flow velocity and substrate composition.The thresholds are calibrated using an ecotope-map of the Western Scheldt of RWS. This map is based on aerial photographs, laser altimetry, soundings, field measurements, and several models. The performance increased from 63 % to 84.6 % after the calibration. This increase is mainly due to (1) differences in the underlying data and (2) the application of deviating thresholds in the ecotope-map of RWS compared to the ZES.1.EMMA is developed for the preliminary design stage. How EMMA can be implemented is demonstrated by applying EMMA on an idealised estuary. Different ecotopes and varying acreages of ecotopes are found when the depth of the estuary is modified.In conclusion, EMMA creates many possibilities for ecotope-maps since it no longer depends on aerial photographs and other real-time data. A translation can be conducted between ecotopes and ecosystem services when a monetary value is preferred, or ecotopes can be broken down into eco-elements, which can subsequently be linked to biodiversity. With EMMA it is possible to predict ecological development, which contributes to the design of NbS. |
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