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Optische remote sensing voor monitoring van chlorofyl en zwevend stof in het Markermeer (concept)
Rijkswaterstaat Midden-Nederland heeft de wens om satellietwaarnemingen te gaan gebruiken voor monitoring van fytoplankton en zwevend stof concentraties, doorzicht, en waterplanten en drijflagen van blauwalgen. Dit rapport is een verslaglegging van het pad dat Deltares heeft ontwikkeld om satellietwaarnemingen die beschikbaar zijn vanaf 2013 tot en met 2017 te bewerken als een pilot voor deze monitoring. Kaarten zijn in digitale vorm via ftp (Host name = ftp.deltares.nl, Ftp account = sparsmm, Password = trpp956) beschikbaar.
Hydromorfologische verbetering ED2050 : opzet morfologisch model
Het Meerjarig Adaptief Programma Eems-Dollard (ED2050) is gericht op het bereiken van een ecologisch streefbeeld in de Eems-Dollard regio. Een onderdeel binnen dit meerjarig programma is het spoor Hydromorfologische Verbetering (HV). De leidende doelstelling binnen dit spoor is het ontwikkelen van maatregelen die een gewenst effect hebben op de morfologische ontwikkeling en op de ontwikkeling van de slibconcentraties in de waterfase. Om een kwantitatief inzicht te krijgen in het effect van maatregelen op de morfologie en slibverspreiding in het Eems-Dollard-gebied worden diverse modelinstrumenten ontwikkeld. Een van deze instrumenten is een morfologisch model. De voorliggende rapportage beschrijft de opzet van dit morfologische model.
Tidal-channel migration between 1997-2014 in relation to the local build-up of the subsurface, The Netherlands
Coastal risk assessment for Ebeye : inception report
The focus of this study is on the two islands of Ebeye and Majuro, respectively located on the Ralik Island Chain and the Ratak Island Chain, which host the two largest population centres of the archipelago. Therefore, the client (The World Bank) has approached Deltares for the development of a coastal hazard assessment for these two islands. The following hazards will be analyzed as part of the study: waves, storm surges, typhoons and tsunamis. Based on this analysis, and specifically for the island of Ebeye, the direct consequences in terms of inundation and coastal erosion are evaluated for different return periods and time horizons, looking at the effect of expected climate change scenario's and sea level rise. The hazard assessment will be used as a basis to carry out the coastal risk assessment, where information on hazards is combined with information on exposure and vulnerability. The output from the risk assessment will allow the determination of weak spots where adaptation measures may be required at present or in the future and for which a conceptual design is proposed. Also, the methodology will allow testing the effectiviness of each of these measures, in achieving the predefined objective in terms of risk reduction.
Exploratory study for the development of ship landing facilities at Niutao and Nanumanga (Tuvalu)
The maritime sector is crucial for connecting the outer islands of Tuvalu with the main port in Funafuti. The small size of the outer islands and the infertile soil make inhabitants heavily reliant on shipping operations. The client (The World Bank) has approached Deltares to carry out an exploratory study to be used as a basis for the development of new maritime infrastructures at the two islands. The study includes the quantification of present and future coastal hazards at the two islands and, based on a multi-criteria analysis, the identification of potential locations for the development of two new ports. At those locations, preliminary port layouts have been outlined, including different configurations for different port sizes, accompanied by initial cost-estimates of the proposed infrastructures. The vulnerability of these infrastructures to present and future coastal hazards has been evaluated. Finally, the possible impact of the new maritime infrastructures on the surrounding coastline (i.e. in terms of morphadynamie changes and coastal flooding) has been analysed.
A conceptual model for the analysis of multi-stressors in linked groundwater–surface water systems
Groundwater and surface water are often closely coupled and are both under the influence of multiple stressors. Stressed groundwater systems may lead to a poor ecological status of surface waters but to date no conceptual framework to analyse linked multi-stressed groundwater – surface water systems has been developed. In this paper, a framework is proposed showing the effect of groundwater on surface waters in multiple stressed systems. This framework will be illustrated by applying it to four European catchments, the Odense, Denmark, the Regge and Dinkel, Netherlands, and the Thames, UK, and by assessing its utility in analysing the propagation or buffering of multi-stressors through groundwater to surface waters in these catchments. It is shown that groundwater affects surface water flow, nutrients and temperature, and can both propagate stressors towards surface waters and buffer the effect of stressors in space and time. The effect of groundwater on drivers and states depends on catchment characteristics, stressor combinations, scale and management practises. The proposed framework shows how groundwater in lowland catchments acts as a bridge between stressors and their effects within surfacewaters. It showswater managers howtheirmanagement areas might be influenced by groundwater, and helps themto include this important, but often overlooked part of the water cycle in their basin management plans. The analysis of the study catchments also revealed a lack of data on the temperature of both groundwater and surface water, while it is an important parameter considering future climate warming.
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Sub-tropical coastal lagoon salinization associated to shrimp ponds effluents
Anthropogenic salinization impacts the health of aquatic and terrestrial ecosystems worldwide. In tropical and subtropical areas, shrimp farm aquaculture uses water from adjacent ecosystems to fill the culture ponds, where enhanced evaporation cause salinization of discharged water. In this study, we studied water salinity before and after shrimp farm harvest and implemented a three-dimensional hydrodynamic model to assess the impact on a subtropical coastal lagoon that receives water releases from shrimp ponds. The shrimp pond discharge significantly increased the salinity of receiving waters, at least 3 psu over the local variation. In the worst-case salinization scenario, when harvest occurs after a long dry season, salinity could increase by up to 6 psu. The induced salinization due to shrimp pond effluents remained up to 2 tidal cycles after harvest, and could affect biota. The methodology and results of this study can be used to assess the impacts of shrimp aquaculture worldwide.
Identifying critical elements in sewer networks using graph-theory
Underground water infrastructure is essential for life in cities. The aging of these infrastructures requires maintenance strategies to maintain a minimum service level. Not all elements are equally important for the functioning of the infrastructure as a whole. Identifying the most critical elements in a network is crucial for formulating asset management strategies. The graph theory is presented as a means to identify the most critical elements in a network with respect to malfunctioning of the system as a whole. As opposed to conventional methods, the proposed method does not rely on iterative hydraulic calculations; instead, the structure of the network is taken as a starting point. In contrast to methods applied in practise, the results are independent on the chosen test-load. Because of the limited calculation effort, the method allows the analysis of large networks that are now, for practical reasons, beyond the scope of methods applied so-far.
An analysis on half century morphological changes in the Changjiang Estuary : spatial variability under natural processes and human intervention
Examination of large scale, alluvial estuarine morphology and associated time evolution is of particular importance regarding management of channel navigability, ecosystem, etc. In this work, we analyze morphological evolution and changes of the channel-shoal system in the Changjiang Estuary, a river- and tide-controlled coastal plain estuary, based on bathymetric data between 1958 and 2016. We see that its channel-shoal pattern is featured by meandering and bifurcated channels persisting over decades. In the vertical direction, hypsometry curves show that the sand bars and shoals are continuously accreted while the deep channels are eroded, leading to narrower and deeper estuarine channels. Intensive human activities in terms of reclamation, embankment, and dredging play a profound role in controlling the decadal morphological evolution by stabilizing coastlines and narrowing channels. Even though, the present Changjiang Estuary is still a pretty wide and shallow system with channel width-to-depth ratios>1000, much larger than usual fluvial rivers and small estuaries. In-depth analysis suggests that the Changjiang Estuary as a whole exhibited an overall deposition trend over 59 years, i.e., a net deposition volume of 8.3×108m3. Spatially, the pan-South Branch was net eroded by 9.7×108m3 whereas the mouth bar zone was net deposited by 18×108m3, suggesting that the mouth bar zone is a major sediment sink. Over time there is no directional deposition or erosion trend in the interval though riverine sediment supply has decreased by 2/3 since the mid-1980s. We infer that the pan-South Branch is more fluvialcontrolled therefore its morphology responds to riverine sediment load reduction fast while the mouth bar zone is more controlled by both river and tides that its morphological response lags to riverine sediment supply changes at a time scale>10 years, which is an issue largely ignored in previous studies. We argue that the time lag effect needs particular consideration in projecting future estuarine morphological changes under a low sediment supply regime and sea-level rise. Overall, the findings in this work can have implications on management of estuarine ecosystem, navigation channel and coastal flooding in general.