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Alle data en modellen voor waterbeheer op één plek en voor iedereen!
Klimaatverandering vraagt veel van ons waterbeheer. Dankzij het Nederlands Hydrologisch Instrumentarium (NHI) kunnen waterbeheerders effecten van maatregelen beter en goedkoper berekenen. Door verbeteringen van Deltares en Wageningen University and Research (WUR) is in 2019 de effectiviteit verder toegenomen.
De polder als batterij bespaart tot 70 procent energie
De gemalen in Nederland kunnen met slimme besturing energie en geld besparen. Door duurzaam opgewekte energie te gebruiken die anders misschien verloren gaat. Deltares ontwikkelde software voor ‘slim malen’.
Hoe staal en grond beter kunnen samenwerken
Stalen damwanden worden al langer gebruikt in waterkeringen in bebouwde gebieden. Dankzij nieuwe softwaremodellen van Deltares weten we nu dat die wanden een stuk dunner kunnen zijn. Dat is net zo veilig, goedkoper en geeft minder overlast bij aanleg.
Grounding big data on climate-induced human mobility
Levee system reliability modeling : the length effect and Bayesian updating
In levee system reliability, the length effect is the term given to the phenomenon that the longer the levee, the higher the probability that it will have a weak spot and fail. Quantitatively, it is the ratio of the segment failure probability to the cross-sectional failure probability. The literature is lacking in methods to calculate the length effect in levees, and often over-simplified methods are used. An efficient (but approximate) method, which we refer to as the modified outcrossing (MO) method, was developed for the system reliability model used in Dutch national flood risk analysis and for the provision of levee assessment tools, but it is poorly documented and its accuracy has not been tested. In this paper, we propose a method to calculate the length effect in levees by sampling the joint spatial distribution of the resistance variables using a copula approach, and represented by a Bayesian Network (BN). We use the BN to verify the MO method, which is also described in detail in this paper. We describe how both methods can be used to update failure probabilities of (long) levees using survival observations (i.e., high water levels and no levee failure), which is important because we have such observations in abundance. We compared the methods via a numerical example, and found that the agreement between the segment failure probability estimates was nearly perfect in the prior case, and very good in the posterior case, for segments ranging from 500 m to 6000 m in length. These results provide a strong verification of both methods, either of which provide an attractive alternative to the more simplified approaches often encountered in the literature and in practice.
Impacts of climate change and remote natural catastrophes on EU flood insurance markets : an analysis of soft and hard reinsurance markets for flood coverage
The increasing frequency and severity of natural catastrophes due to climate change is expected to cause higher natural disaster losses in the future. Reinsurance companies bear a large share of this risk in the form of excess-of-loss coverage, where they underwrite the most extreme portion of insurers’ risk portfolios. Past experience has shown that after a very large natural disaster, or multiple disasters in close succession, the recapitalization need of reinsurers could trigger a “hard” reinsurance capital market, where a high demand for capital increases the price charged by investors, which is opposed to a “soft” market, where there is a high availability of capital for reinsurers. Consequently, the rising costs of underwriting are transferred to insurers, which ultimately could trigger higher premiums for natural catastrophe (NatCat) insurance worldwide. Here, we study the vulnerability of riverine flood insurance systems in the EU to global reinsurance market conditions and climate change. To do so, we apply the “Dynamic Integrated Flood Insurance” (DIFI) model, and compare insurance premiums, unaffordability, and the uptake for soft and hard reinsurance market conditions under an average and extreme scenario of climate change. We find that a rising average and higher variance of flood risk towards the end of the century can increase flood insurance premiums and cause higher premium volatility resulting from global reinsurance market conditions. Under a “mild” scenario of climate change, the projected yearly premiums for EU countries, combined, are €1380 higher under a hard compared to a soft reinsurance capital market in 2080. For a high-end climate change scenario, this difference becomes €3220. The rise in premiums causes problems with the unaffordability of flood coverage and results in a declining demand for flood insurance, which increases the financial vulnerability of households to flooding. A proposed solution is to introduce government reinsurance for flood risk, as governments can often provide cheaper reinsurance coverage and are less subject to the volatility of the capital markets.
Proceedings of the HYDRALAB IV Joint User Meeting, Lisbon, July 2014
Historical overview of 2D and 3D hydrodynamic modelling of shallow water flows in the Netherlands
This paper contains a historical overview of 2D and 3D hydrodynamic modelling in the Netherlands from the 1960s till now. It started in the 1960s with two-dimensional (depth-averaged) shallow sea modelling for practical applications of the Dutch government. The most important application was the Dutch ‘Delta works’ project, which was initiated after the February 1953 flood disaster in the Netherlands. In the late 1980s, three-dimensional shallow water modelling in the Netherlands started due of the advance in computing power. This was also needed for 3D water quality modelling. Two large software suites have been developed for modelling of shallow water flows in the Netherlands, namely Simona and Delft3D. These integrated systems contain software for modelling of hydrodynamics, water quality, morphology and waves. In this paper, we focus on hydrodynamic modelling. In literature, a lot of applications of Delft3D and Simona have been described. However, in none of these papers, the key features of the underlying hydrodynamic numerical method have been described, which have resulted into a good performance with respect to robustness, accuracy and computational efficiency. This paper therefore summarizes ‘proven technology’ in shallow water modelling with Simona and Delft3D that has been applied in the past decades in the Netherlands and abroad. From the 1960s till now, the hydrodynamic modelling in the Netherlands has been based on structured grids. In 2011, a transition started in the Netherlands towards unstructured modelling for shallow water flows, which will be discussed as well.
Sediment dynamics and transport regimes in a narrow microtidal estuary
Estuarine sediment dynamics are a consequence of various forcings (barotropic, estuarine circulation, and fluvial) that vary in space and time. Here, we present a study examining sediment dynamics in a narrow microtidal estuary, the Lower Passaic River in New Jersey, USA. The analysis incorporates measurements of suspended sediments, morphological change, sediment erodibility, and a numerical hydrodynamic model. The former two datasets are used to develop an understanding of sediment dynamics over the full range of hydrologic conditions, and the latter two datasets are used to interpret the behavior of the system. Subsequently, a conceptual picture is developed, one that classifies the morphological status of the system at any given time into three regimes dependent on river flow—regime I includes conditions when the system is importing sediments, regime II includes conditions when the system is exporting sediments by flushing a thin easily erodible surficial stratum termed the fluff layer, and regime III includes conditions when the system is exporting sediments by scouring more consolidated strata underneath the fluff layer. Regime III is relevant for the long-term morphodynamic equilibrium of the estuary by providing a mechanism that erodes and exports sediment accumulated under regime I conditions. Consequently, sediment dynamics depend not only on short timescale processes such as the instantaneous river flow rate, but also on the time-history of river flow, and the long-term morphological progression of the system. These regimes represent a conceptualization of estuarine sediment transport dynamics and can be useful in the development of effective estuarine sediment management strategies.
Groot Mijdrecht: inzicht in functioneren wellen
Polder Groot Mijdrecht is een droogmakerij in het uiterste noordwesten van de provincie Utrecht. Het is een van de diepste droogmakerijen van Nederland met een diepteligging van ruim zes meter beneden NAP. Door de diepe ligging ten opzichte van de omgeving én door een deklaag met lage weerstand, stroomt zeer veel grondwater naar Groot Mijdrecht. De provincie Utrecht en het Hoogheemraadschap Amstel, Gooi en Vecht hebben een onderzoek gestart naar de toekomstmogelijkheden voor Groot Mijdrecht (2008). Voor dit onderzoek zijn diverse modellen opgezet en verbeterd. Het grondwatermodel van Groot Mijdrecht is uitgebreid met een wellenregel.