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Model Predictive Control of salinity in a polder ditch under high saline groundwater exfiltration conditions : a test case
Surface water salinization in deltaic areas due to saline groundwater exfiltration is an important issue. Saline surface water will not be appropriate for drinking water production, agricultural and industrial use, and therefore, freshwater diverted from rivers is used for flushing the canals and ditches in coastal areas. The effects of climate change, sea level increase and fresh water availability increases the stress on deltaic areas resulting in questioning current fresh water management strategies. In this paper, a Model Predictive Control (MPC) scheme is developed and tested for combined salinity and water level control of a polder ditch. The MPC scheme is coupled with Rapid Saline Groundwater Exfiltration Model (RSGEM) developed for fast calculation of exfiltration flux and concentration in a low-lying polder. For the test case presented in this paper, real data from Lissertocht catchment in Netherlands is used for RSGEM to see the performance of the MPC scheme for a real scenario. With open space for further research, results presented on this paper show that MPC of salinity in polders is capable of dealing with saline groundwater exfiltration modeled by RSGEM.
Werkplan watersysteemrapportage Oosterschelde en kenniscommunity : voor het opstellen en actueel houden van een digitale watersysteemrapportage
Dit werkplan behandelt twee generieke vragen: 1)Hoe kan met (nut voor meerdere partijen een brede watersysteemrapportage worden opgesteld?, 2)Hoe kan een watersysteemrapportage actueel gehouden worden?De beantwoording wordt toegepast op de Oosterschelde, maar is tegelijkertijd bruikbaar voor andere wateren. Een nevendoel is het creëren van een gedeeld beeld en een gemeenschappelijke taal rondom begrippen als kennisbasis, kennismanagement en kenniscommunity en rondom de mogelijkheden van digitaal rapporteren gebruikmakend van moderne technieken en ontsluiting via internet. Uitganspunt van het werkplan is dat een kenniscommunity-dat wil zeggen een samenwerkingsverband van partners met als gemeenschappelijk doel om de systeemkennis van de Oostersehelde te borgen en actueel te houden-een voorwaarde is. Door middel van de kennis community en de daaraan ten grondslag liggende afspraken, organisatie en middelen (tijd en budget) is continuïteit geborgd.
What is the Ghijben-Herzberg principle and who formulated it?
It has been suggested in a number of historical notes that it was neither Willem Badon Ghijben nor Alexander Herzberg who formulated the famous principle now carrying their name, which relates the water-table elevation to the depth of the freshwater–saltwater interface in coastal aquifers. In this paper, a systematic review of the literature pre-dating the publication of their work is presented. The aim is to establish to what extent these previous works captured the essence of the Ghijben-Herzberg principle, that is, the combination of a correct conceptual model of the hydrogeological conditions with a quantitative relationship. It was found that references to coastal fresh groundwater reserves can be traced back to Roman times, while the earliest detailed descriptions of a freshwater lens that could be found dates from the eighteenth century. The correct understanding of the hydrostatic equilibrium between fresh and salt groundwater is evident in works from the early nineteenth century. However, it was Badon Ghijben and Herzberg who combined this with the correct understanding of the groundwater conditions of a freshwater lens. It was further found that Herzberg had already recorded his findings in 1888 in a hand-written report, confirming speculation that such a report might exist.
Wave overtopping over dikes with oblique wind and swell waves
Most guidelines on wave overtopping over coastal structures are based on conditions with waves from one direction only. Here wave basin tests with oublique wave attack are presented where waves from one direction are combined with waves from another direction. This is especially of importance for locations where wind waves approach a coastal structure under a specific direction while swell waves apporach the coastal structure under another direction.
Coastlab18 : proceedings of the 7th International conference on the application of physical modelling in coastal and port engineering and science (Santander, Spain, May 22-26, 2018)
Exploring potential climate change impacts and adaptation strategies for seaport operabilty
As seaports are located within the coastal zone, they are susceptible to climate change impacts such as changing wave conditions and sea level rise. To secure the operability of seaports under these changing conditions, a deeper understanding of potential local-scale climate change impacts is needed to explore suitable adaptation strategies. Previous studies focused on climate change impacts on seaports at a regional scale. Consequently, there remains a lack of understanding of these impacts on individual seaports and how these seaports can accommodate or adapt to these impacts. This study provides a conceptual framework for (i) quantifying risks for port operability and (ii) exploring adaptation strategies. The framework is tested on a case study of the Port of IJmuiden in the Netherlands. The study demonstrates that in the absence of adaptation measures, climate change may result in significant risks for the operability of this port. While the framework is tested on a single case study site, it is believed to be a promising tool for exploring climate change risks and adaptation strategies for seaports worldwide.
Proceedings of the 34th PIANC World Congress 2018 (Panama City, Panama, May 7 to 11, 2018)
Sensitivity of native and alien freshwater bivalve species in Europe to climate-related environmental factors
While native freshwater bivalve species are declining, several alien bivalve species have become invasive, thereby impacting ecosystem functioning and services. These biodiversity changes can be attributed to deteriorated water quality, hydro-morphological alterations, and the overarching effect of global change. Therefore, a systematic assessment of the sensitivity of freshwater bivalve species nowadays occurring in European inland waters to environmental factors is urgent. The present study reviewed 493 relevant papers, resulting in 8405 data entries on presence–absence of bivalve species in relation to environmental factors that are affected by global change (i.e., water temperature, water depth, oxygen availability, and flow velocity). From these worldwide field data, minimum and maximum values measured in their habitat and water bodies were selected. In addition, data on laboratory-derived tolerance ranges were collected. Subsequently, novel species sensitivity distributions (SSDs) were derived for each environmental factor using field-based occurrence data and laboratory-derived tolerance ranges, respectively. Species sensitivity distributions for maximum habitat temperature significantly differed between native and alien species. The latter occurred in habitats with higher maximum water temperatures than native species. The increase in water temperatures by global warming will affect a higher percentage of native species than alien species. The ranking of species based on their sensitivity for various environmental factors shows that vulnerable and endangered species have a higher overall sensitivity and are likely to be more affected by climate change. Invasive alien species were found to have a lower overall sensitivity and are thus less affected by climate change further aiding to their invasive nature. The available SSDs allow the ranking of freshwater bivalve species sensitivity to environmental stressors, the prediction of their potential occurrence in freshwater habitats, and the evaluation of management measures to optimize their biodiversity and ecosystem services.
Coastal hazard risk assessment for small islands: assessing the impact of climate change and disaster reduction measures on Ebeye (Marshall Islands)
Small island states around the world are among the areas most vulnerable to climate change and sea level rise. In this paper, we present results from an innovative methodology for a quantitative assessment of multiple hazards on coastal risks, driven by different hydro-meteorological events, and including the effects of climate change. Moreover, we take an additional step by including in the methodology the option to assess and compare the effectiveness of possible disaster risk reduction measures. The methodology is applied to a real case study at the island of Ebeye (the Republic of the Marshall Islands). An example is provided in which a rock revetment is implemented as a risk reduction measure for the island. Results show that yearly expected damages may increase, by the end of the century, by a factor of three to four, depending on the sea level rise scenario considered, while the number of yearly affected people may double. Putting a cap on the temperature increase (e.g. 1.5 vs. 2 °C) according to the Paris Agreement may reduce damages and number of affected people by about 20 and 15%, respectively. However, impacts for same warming levels can vary substantially among different emission scenarios. Disaster risk reduction measures can be useful for mitigating risks in current and future situations but should be incorporated within long-term adaptive planning for these islands.
Nieuwe overwegingen voor maaibeheer met vlakdekkende informatie over vegetatie
Vegetatiebeheer in watergangen gebeurt bij veel waterschappen door maaien via vooraf vastgestelde maaibestekken. Vlakdekkende informatie geeft inzicht in de daadwerkelijk aanwezige vegetatie in een stuwpand en het effect hiervan op de doorstroomcapaciteit. Met een multispectrale camera is de ruimtelijke verdeling van vegetatie over een proeftraject in kaart gebracht en de hydraulische impact van deze vegetatie op de waterpeilen gekwantificeerd. Hieruit blijkt dat het substantieel uitmaakt waar deze vegetatie zich bevindt. Voor een risicogestuurd maaibeheer is het nuttig om deze informatie voor een heel stuwpand te hebben en zo duidelijke keuzes te maken waar en wanneer er gemaaid moet worden.