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dc.rights.licenseCC-BY-NC-ND
dc.contributor.advisorBierkens, M.F.P.
dc.contributor.authorHuizen, M.E.R. van
dc.date.accessioned2017-08-21T17:02:42Z
dc.date.available2017-08-21T17:02:42Z
dc.date.issued2017
dc.identifier.urihttps://studenttheses.uu.nl/handle/20.500.12932/26949
dc.description.abstractDuring extreme rainfall conditions, the Greenport Boskoop is highly vulnerable to water nuisance. Water nuisance was observed previously inside water level areas in the Gouwepolder, situated in the east of Greenport Boskoop. This thesis specifically focuses on water nuisance that is caused by interacting water level areas in the Gouwepolder. In the past, several parcels located inside lower water level areas in the Gouwepolder experienced water nuisance orginating from the surface water system in the higher compartiment. Damage to horticultural production was limited due to the removal of floodwater within 48 hours. Future climate change is expected to increase the occurrence of extreme rainfall conditions and the probability of water nuisance, while horticultural production may irreversibly be damaged when the soil is fully saturated for more than two days. According to a former study by the Rijnland Water Board, which is responsible for the management of surface water and other local water structures in the Greenport, the average protection height of parcels that separate water levels areas should be increased in order to reduce or prevent this flooding phenomenon. There are still a number of questions: (1) whether the water level border should be upgraded entirely, (2) what is the optimal height of the new construction and (3) what construction types and materials can be used. These questions are relevant to determine the cost-efficiency of a structural measure for the water level areas in the Gouwepolder. The resilience of local surface water systems to water nuisance is assessed on the basis of national protection standards included in the National Administrative Agreement on water (Nationaal Bestuursakkoord Water, henceforth: NBW). The NBW assessment for the Gouwepolder has identified many potential flooding locations at water level borders, which at present fail to meet the protection standard for horticulture. Due to the establishment of NBW standards nationally, it may be questionable whether these standards also provide the optimal protection level locally. In current dike improvement projects along large Dutch rivers, a more risk-oriented approach is currently used by Water Boards. This is based on cost estimates of flood damage and investment in protection, to determine the most cost-efficient protection level. This concept has been centralized in this thesis, to determine on the one hand whether it may improve protection levels and on the other hand whether the Gouwepolder and the Rijnland Water Board can benefit in economic terms from this approach. Inundation damage caused by surface water or groundwater within water level areas of the Gouwepolder was studied before by Huizinga and Groot (2012). In this thesis, inundation damage was estimated for the water level area of Koetsveld, which specifically originates from a different surface water system (Gouwepolder). Firstly, potential water nuisance was determined by simulating inundation maps for several return periods in relation to the pertinent protection level. Secondly, a spatial model was developed which calculated inundation damage for four dominant land-use classes (open field cultivation, pot-and container cultivation, meadow and greenhouse), by converting inundation depth to damage with characteristic depth-damage functions. Furthermore, the protection level was manually changed to determine how flood damage estimates change in relation to higher protection. Additionally, the full protection approach and critical protection approach were formulated in the model to identify the effect of different protection strategies on estimated flood damage. Furthermore, a second spatial model was developed to collect information about the current protection level and what is required to increase the water level border protection. The calculation results for flood damage and protection have been culminated into a single Excel file, that calculates curves for both the flood damage costs and protection costs for a defined project period. According to the results, the optimal protection level for the full protection approach, whereby the entire water level border is upgraded, closely matches the actual protection standard for horticulture. Different results were obtained for the critical approach, whereby only selected critical locations are upgraded. Firstly, the optimal protection level, in case of a low unit price, couldn’t be extracted from the protection levels, as considered in the analyses. In contrast, an optimum was found close to -1,88 m NAP for a high unit price, which is higher than the actual protection standard for horticulture. This protection level results in an annual flood risk reduction from 35.000 EUR up to 10.000 EUR. Obviously, the total investment cost for flood protection in this strategy is lower due to the smaller construction size. The higher protection level was probably found due to lower investment cost for the critical protection strategy. Furthermore, it was found that the cost-efficiency of measures is generally lower for the full protection approach than for the critical protection approach. The cost and benefit ratio for a 30-year project period is negative for almost all protection levels for the full protection approach, while the critical protection strategy shows a positive ratio. It is however important to note that these conclusions for the protection strategies have been drawn from just one composition of construction materials, which was primarily the composition with the highest cost-efficiency. This combination is mainly based on the following construction materials: clayish peat (open field cultivation and others), EPS or foam concrete (pot-and container cultivation) and bamboo (greenhouses).
dc.description.sponsorshipUtrecht University
dc.format.extent6635064
dc.format.mimetypeapplication/pdf
dc.language.isoen
dc.titleWater nuisance in Greenport Boskoop: "Searching for a cost-efficient strategy to reduce water nuisance from interacting water level areas in the Gouwepolder"
dc.type.contentMaster Thesis
dc.rights.accessrightsOpen Access
dc.subject.keywordsWater nuisance, Greenport Boskoop, Gouwepolder, horticulture, water level area, inundation risk, inundation damage, flood protection, spatial modelling,
dc.subject.courseuuWater Science and Management


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