Delft & Leeuwarden, The Netherlands
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Publications

Papers / Articles / Reports (in English)

Author: Kees Pieters

Download: Publicatie_KeesPieters-170x240mm_LR

Description: Unmanned systems are all the hype today. Following the extremely dynamic developments in the automotive industry, the maritime industry is preparing for a future where human presence is no longer required in the logistical chains or on board ships. The advocates of these developments promise great opportunities and talk of ‘Smart Ports’, ‘Smart Cities’, ‘Smart Vessels’ and a lot of other smart things where “Big Data”, “Deep Learning” and the “Internet of Things” are driving a strong technology push in this direction. There are also more critical voices, which stress the threats to job security and safety, and even warn against the consequences of robot supremacy. In the past four years, Research Centre “Sustainable PortCity” has been at the forefront of these debates, both with regard to the maritime industry and Rotterdam Mainport, as a city where people live, work and spend their leisure time. 
 
 
 

Authors: Rui L. P. DE LIMA , Vladislav SAZONOV , Floris C. BOOGAARD , Rutger E. DE GRAAF

Download: a5b9e72262c8535c6e7f2f9c3136ca89

KEY WORDS: submerged drone, water quality, dissolved oxygen, floating urbanization, climate change

Underwater drones for water quality monitoring – a survey on the impacts of floating structures on water quality and ecology (paper submitted for the conference “Drones and Hydraulics” and journal: “La Houille Blanche”)

Authors: R. L. P. de Lima*, F. F. Boogaard**, R. E. de Graaf

Download: ab7da1869ce6fda008443079a0e4e778

Abstract: Floating urban solutions offer flexibility and resilience that can contribute for improved and sustainable cities. In order to better understand and analyse how floating structures impact their surrounding environment, a remote-controlled underwater drone was used to collect dynamic water quality and ecology datain the vicinity of floating structures. The drone was equipped with multi-parameter water quality sensors and with HD video cameras, which allowed to observe underwater aquatic life. Several different locations around The Netherlands were visited and studied. Some interesting relations between the characteristics of the structures and patterns in the differences in average dissolved oxygen concentrations between open water and zones
near/under floating structures were accomplished (e.g. material of the structures, available space under the structures). Results indicate that the impact of current small scale projects are not significant regarding dissolved oxygen concentrations, and that this type of floating projects can even have a positive impact on ecology.

Authors: R. L. P. de Lima*, F. C. Boogaard**, R. E. de Graaf. 

File: ab7da1869ce6fda008443079a0e4e778 (1)

Abstract: Floating urban solutions offer flexibility and resilience that can contribute for improved and sustainable cities. In order to better understand and analyse how floating structures impact their surrounding environment, a remote-controlled underwater drone was used to collect dynamic water quality and ecology data in the vicinity of floating structures. The drone was equipped with multi-parameter water quality sensors and with HD video cameras, which allowed to observe underwater aquatic life. Several different locations around The Netherlands were visited and studied. Some interesting relations between the characteristics of the structures and patterns in the differences in average dissolved oxygen concentrations between open water and zones near/under floating structures were accomplished (e.g. material of the structures, available space under the structures). Results indicate that the impact of current small scale projects are not significant regarding dissolved oxygen concentrations, and that this type of floating projects can even have a positive impact on ecology.

 

Author: Hannah Härtwich,

Download: 5a8543af1e878f8632bb53a02fb06fbd

Description: Floating architecture offers new building space and is not vulnerable to flooding, making it an attractive solution for coastal cities facing population growth and increasing flooding risk due to climate change. Before increasing the use and size of floating structures, their impact on the environment should be analysed, in order to avoid undesired environmental change. In this study, the hypothesis that floating platforms change the availability of light and organic carbon in the benthic ecosystem, leading to differences in the benthic community structure under the platform compared to the surrounding area, was tested at four floating platforms in the Netherlands. Measurements taken with an underwater drone confirmed the colonisation of the platforms with filter feeders as well as the absence of macrophytes under the platforms and showed lower oxygen contents under one of the four platforms. Sediment samples were taken at one of the platforms and showed higher organic matter content and respiration rates under the platform compared to samples taken around the platform. For the same platform, no differences in the redox potential and the macroinvertebrate community structure could be observed. A model for the light intensity under floating platforms was developed, showing that an area of low light intensity can exist under the platform, but this area can be minimised by optimising the design of the platform. Based on the results of this and previous studies, a conceptual model showing the interactions of impacts of floating platforms was developed. Depending on the design and location of the floating platform and the sensitivity of the benthic ecosystem, the platform can result in desired or undesired changes. Recommendations to minimise the undesired and optimise the desired changes are therefore given. Further research is needed for confirming the findings of this study and for extending and refining the recommendations on the location, design and management of floating platforms in order to expand their use without causing undesired environmental change.

 

Authors: Hannah Hartwich

Download: 9dccedca4e3ecedab8801630334211ec

Description: Land scarcity and eutrophication are challenges for the future development of cities and healthy ecosystems. The design, research and consultancy firm DeltaSync developed a concept for a floating city, combining algae culture and aquaponic systems and urban construction on water,
to find possible solutions to these challenges. If this new concept is implemented in the future, an Environmental Impact Assessment will have to be undertaken, following the EU Directive 2011/92/EU. Based on this directive, the impact of floating cities is analysed in this report, to determine if floating cities are an approach for future cities that can have advantages for the environment. This analysis includes a comparison with the impact of land based cities. The information about the extent of impact available at the moment does not yet allow a definite conclusion of the assessment. Several aspects argue for the environmental benefits of the floating city concept developed by the design, research and consultancy firm DeltaSync. Floating wetlands
work against eutrophication, the food production system is based on waste nutrients and CO2 and the flexibility of the floating buildings allows to use less resources. But to ensure that the benefits prevail, measures will have to be implemented to avoid negative impact of floating cities, as for example the formation of an anaerobic zone under the platforms. The assessment of the aspects with potential negative impact provides first advice for optimising floating cities, minimising the negative impact and choosing suitable locations for the construction of floating cities, helping to ensure a more positive effect on the environment and hence allowing the project to pass an Environmental Impact Assessment. Additionally, this analysis can help to raise awareness and serve as an introduction to aspects of the environment, which should be considered from the beginning when planning a project.

Author: Efthymia Foka

Download: af3238e6132cbab78bed2afd5030e937

Description: The growing agglomeration and climate change are two challenges for the urban areas, which result in the reduction of permeable surface, the increase of surface runoff and a change in the temperature and precipitation patterns. These, in addition to the uncertainty of the climate change, point towards the need for adaptive sustainable solutions. Floating urbanization is an old concept, which recently is gaining attention since it combines solutions for the above-mentioned problems. A number of aspects need to be investigated in order to move forward with the implementation of floating urbanization. One of them is the effect on the water quality and ecology. Since water quality is a complex problem this thesis will focus on the effect of floating houses on Dissolved Oxygen levels. A small floating residence in the area of Delft will serve as a case study. In this area a measurement campaign in the months of July to September 2013 was conducted in order to collect data, which later served to assess the impact of the floating houses. The results from the field measurements were further evaluated by analyzing which physical property or weather condition is responsible for the observed Dissolved Oxygen differences. Later on, a numerical model was developed in order to analyze in more detail the sources of these effects on Dissolved Oxygen. In particular the consequences of shadow and wind tunnel effect, induced by the floating houses, were studied. The results of the measurements and numerical simulations showed that there are differences on the Dissolved Oxygen levels in the upper part of the water column. The average measured differences are close to 10% (1mg/L), similar to the results obtained by the numerical models. Nevertheless, both of the floating houses effects (shadow and wind tunnel) are active on the same region of the water column, which makes it difficult to isolate their contributions. Finally, the small amount of data collected and the uncertainty that is inherent in water quality modeling hinder us from drawing a definite conclusion regarding the effects of floating houses on Dissolved Oxygen levels. Further research and improvements on data collection and model development is recommended.

Authors: M.L. Bol and M.L. Tobé 

Download: 09394aabcbee83774b56a13adf743aba (1)

Description: With climate change causing among others an increase of intense rainfall, it is found a necessity to build more climate adaptive and water resilient. Due to an increasing land scarcity and population density, this sometimes means searching for solutions in more innovative and cost efficient ways such as the concept of building on water. As for most innovations, projects are delayed or postponed due to uncertainty about the possible negative effects (e.g. financially, ecologically) and are some regulations not (yet) adequate to enable such developments. Though the realization of floating structures is being carried out for a long time (e.g. houseboats), it is still unknown what the effects of such structures are on the aquatic environment. Exploratory research on small scale floating projects (single structures) showed that these are not significant when comparing the gathered data from underneath and nearby the structure with that collected at open water. This also applies for the investigated enlarged floating project (e.g. floating community IJburg, Amsterdam). However, all collected measurements were not assessed according to the water quality standards used by the responsible water authority and only a few decisive parameters were measured. The first part of this exploratory research therefore centers on the impact of enlarged floating projects, measuring more parameters then was done in previous researches and reviewing the gathered data using the standards of the water authorities. The available measuring equipment could however only measure physical and chemical elements (e.g. temperature, dissolved oxygen, conductivity and salinity). Therefore only those components are compared with the values allocated by the Water Framework Directive for each type and category. Nevertheless, a basic insight about the determinative physical-chemical parameters is also given. To assure more representative and reliable conclusions at the end of this research, the choice is made to investigate a limited amount of case study locations. This creates the possibility to gather data from the same location more often, giving a more detailed insight in the local water quality effects of floating structures and reduces the chance of measurement errors. For conducting the measurements a remotely operated underwater vehicle (ROV) is used, equipped with various water quality sensors and a video camera (GoPro 3+). Because the ROV is still in the development phase, improvements and modifications will be proposed and implemented during and after the research period of this investigation. Being the only available enlarged floating project already realized in the Netherlands, the results of IJburg make it the primary location to research. Collected data here did not show a significant difference in comparison to the open water. Considering the data collected during this study, it is therefore concluded that the floating community in IJburg does not worsen the water quality on the measured parameters. This also applies for most of the other investigated locations of which, with the exception of some, the gathered data did not show significant inexplicable differences. However, the conclusions only represent the measured parameters making it still not possible to determine the actual effects of (enlarged) floating projects. This can only be done by investigating (possible) effects over a longer period of time, according to the requirements stated in the Water iv Framework Directive and EBEO methodology. Starting with the gathering of all parameters (biological, hydro morphological, physical and chemical). Previous researches indicated that the regulations and restrictions formulated in the policies used by the (water) authorities, applicable on floating structures, were found to be limited available and also deviate per water board. Therefore, in the second part of this research, an inventory of these policies is made by investigating the current policy plans (which lasted from year 2010 till 2015) and the revised versions operative from the year 2016 till 2021. In addition, the development within the water authorities concerning this subject is examined. Besides a literature study, meetings with ecologists, policy advisors and permitting authorities of the relevant water authorities are held for the further gathering of information. Resulting from researching all the relevant policies and correspondences with Union of water boards, there is no general policy found regarding floating objects. Acknowledged by the Union of water boards, this originates from several reasons, namely:  the differences in priorities set by each water board;  the need for a certain amount of autonomy in processing national ambitions to their own administrative area;  the absence of urgency to actively help the development of floating projects, due to the conviction that it is not part of their core tasks. Additionally, it is found that the development of new policy regarding floating objects is also being postponed by the lack of information concerning the relation between large scale floating projects and the effects this might have on the aquatic system. When proven that (enlarged) floating projects have a negative effect on the water quality, it is recommended to include ecological stimulating measures in the policies in order to mitigate those effects. Therefore the third and last part contains measures that could mitigate possible negative effects caused by the floating structures. These measures were selected on the basis of two criteria: target functions and applicability. Functions are divided in primary and secondary categories. Primary target functions are water purification and habitat enhancement, focusing on the main subject of this study, the restoration of the aquatic environment when negatively affected by floating structures. Secondary functions are green landscaping and the reduction of wave forces which contribute to the social and spatial quality of the floating environment. Regarding to the applicability, criteria for the selected ecological measures were to have the capability to be implemented stand-alone and/or to be attached to the floating structures. From this two sub-surface and two floating measures were defined which are respectively geotextile tubes/bags and artificial reefs and wet- and dry type floating islands. Applications to these measures such as mussel strings and aeration systems add more target functions or increase the performance. The choice of which measure should be applied, depends on predetermined objectives for the specific area (e.g. water treatment, habitat enhancement), characteristics of the water system and the local environment. Besides wetlands which are applied and tested worldwide, little information is known about the effectiveness of each ecological measure. Therefore it is necessary to gain insights on the effectiveness of the realized ecological measure. This can be achieved through dynamic monitoring v with a ROV so the development and aquatic effects of the object can be observed and changes could be made to its design. The existing policies used by water authorities and municipalities is found to be adequate for development of (small scale) floating projects similar to those already permitted. In order to allow the development of large scale floating projects (e.g. floating community in IJburg, Amsterdam), these policies might not be sufficient. Although this research indicates that there are no significant effects of floating structures on the water quality, this only applies for the measured parameters. By researching allspecific effects of floating objects on the aquatic ecology allows water boards to determine whether or not forming new policy is actually necessary. For this, it is recommended to include ecological stimulating measures in order to mitigate possible negative effects.

Author: Janko Lenz

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Description: Large floating structures have the potential to overcome the challenge of land scarcity in urban areas. They offer opportunities for energy and food production or even habitation. On the other hand they influence the physical and chemical characteristics and hence living conditions in the water body they are floating in. A monitoring of these impacts is needed to enable the development of building legislation on future construction projects.

For the present thesis floating houses at Himpenser Wielen in Leeuwarden (Netherlands) were selected, were a measurement campaign was carried out in autumn 2017. Two multiparameter probes were utilized for monitoring of water temperature and dissolved oxygen content. Pioneering work was a 10-day measurement under a floating house. Vertical temperature profiles were recorded to detect differences in heat transport. Additionally an underwater drone was used for investigation of mussels and macrophytes underneath the floating house. Water temperature was lower in open water compared to the area under the house, by 0.15K on average. Checked against the shaded area it was lower by 0.14K at the water bottom and 0.1K near the water surface respectively. Dissolved oxygen content was higher in open water than in shaded area, by 0.8mg/l in shallower and 2.8mg/l in greater depths.

Long-term measurement has a high potential for monitoring the environmental impact of floating houses. In the presented thesis it could show diurnal cycles of water temperature

and dissolved oxygen, also in greater depths. Moreover a high dependency of these

parameters on weather condition was determined.

Further research, taking at least one year, would show effects of floating structures on the

seasonal variations of water temperature and dissolved oxygen content. Other parameters,

like nutrients, should also be investigated over longer periods. In addition the development of

a more suitable method for measurement under floating houses remains as a challenge.

Download:Binder1

Monitoring water quality with drones: Indymo is a start-up that works in the field of managing water resources. The focus is on innovative ways of monitoring water quality and ecology, and in inspections of underwater infrastructure (e.g. underwater drones). Indymo has conducted its activity mostly within the Netherlands but has recently been involved in international projects as well.

Full magazine: https://issuu.com/tudelft-mediasolutions/docs/hoi-robotics

Papers / Articles / Reports (in Dutch)

Author: Floris Boogaard 

Download: 98bac40814d97bfde2e9241c908450a3

Description: De resultaten van het Valorius programma Een uitgave van de Stichting Klimaat voor Ruimte en de CKW partners

Authors: Merijn de Buck,  Kevin van der Linden 

Download: 31351cab5dce94774dfee86c16f77cc0

Description: De klimaatverandering zorgt voor belangrijke (inter-)nationale ontwikkelingen op het gebied van ruimtelijke ordening en waterveiligheid. De kans op wateroverlast en overstromingen in zowel binnen- als buitendijkse gebieden is de afgelopen jaren toegenomen en zal de in de toekomst verder toenemen. Een strategie om deze kans op wateroverlast en overstromingen tegen te gaan is klimaatadaptief bouwen. Een vergaande vorm hiervan is “drijvend bouwen”, oftewel het bouwen van drijvende constructies op water. Deze constructies zijn aanpasbaar, verplaatsbaar en flexibel en kunnen met een juist ontwerp meebewegen met een fluctuerend waterpeil. De ontwikkeling van drijvende projecten wordt echter belemmerd door enerzijds een gebrek aan beleid bij waterschappen en gemeenten en anderzijds een gebrek aan kennis. Met name de mogelijke effecten van drijvende bebouwing op de waterkwaliteit is een belangrijk aspect waar weinig over bekend is. De kennisontwikkeling, betreffende de effecten van drijvend bouwen op de waterkwaliteit, is het onderwerp van dit afstudeeronderzoek. Waterkwaliteit is echter een ruim begrip en de vraag wat de effecten van drijvende objecten op de waterkwaliteit zijn, is moeilijk te onderzoeken. Daarnaast geeft het consortium ”Drijvend bouwen” aan nog geen behoefte te hebben om de waterkwaliteit in zijn geheel in kaart te brengen. Daarom zijn in dit afstudeeronderzoek drie parameters onderzocht die de waterkwaliteit (deels) bepalen: het zuurstofgehalte, de temperatuur en de ecologische toestand van het water. Door middel van literatuuronderzoek en veldmetingen is onderzocht wat de mogelijke effecten zijn van drijvende constructies op de genoemde parameters. Aan de hand van een portfolio met drijvende projecten in Nederland zijn verschillende onderzoekslocaties geselecteerd voor de veldmetingen. Voor het meten van zuurstof en temperatuur werd apparatuur geplaatst onder de drijvende bebouwing: dit betreft een meting “bij aanwezigheid van drijvende bebouwing”, het zogenaamde meetpunt. Gelijktijdig werd ook meetapparatuur geplaatst op een punt buiten de drijvende bebouwing: de meting “bij afwezigheid van drijvende bebouwing”, het zogenaamde referentiemeetpunt. Door deze twee metingen met elkaar te vergelijken zijn eventuele verschillen in kaart gebracht. De ecologie is volgens dezelfde methodiek in kaart gebracht. Met visuele opnamen (camerabeelden) onder en boven water kon de ecologische toestand op de verschillende punten in worden bekeken. De eventuele verschillen in het zuurstofgehalte, de temperatuur en de ecologie tussen het meetpunt en referentiemeetpunt konden (in sommige gevallen) worden verklaard en wijzen op de “mogelijke effecten” van drijvende bebouwing. Uit de onderzoeksresultaten is gebleken dat effecten waarneembaar zijn van drijvende bebouwing op de eerder genoemde parameters. Zowel positieve als negatieve effecten zijn waargenomen. Eén van deze positieve effecten is bijvoorbeeld de aangroei van mosselen aan de drijflichamen van drijvende bebouwing. Deze mosselen voeden zich met algen, filteren het water en bevorderen de waterkwaliteit. Een mogelijk negatief gevolg is een afname van het zuurstofgehalte onder de drijvende bebouwing. Lage zuurstofconcentraties verminderen de waterkwaliteit en kunnen het leefmilieu van flora en fauna aantasten. De afname van het zuurstofgehalte nabij drijvende bebouwing wordt met name veroorzaakt door een gebrek aan zonlicht. Ondanks dergelijke negatieve verschijnselen heeft de drijvende bebouwing in dit onderzoek, niet geleid tot overschrijding van de kwaliteitsnormen voor het minimale zuurstofgehalte en de maximale temperatuur van het water.

Authors:  Paul van Eijk, Rui de Lima, Jan Roelsma en Lisette van der Berg

Download: 0af549956e326b9c3781fd84651e5870

 

Wetterskip Fryslân, Hogeschool Van Hall Larenstein en Indymo voeren
onderzoek uit naar de toepassingsmogelijkheden van onderwaterdrones.
Er zijn veel toepassingen mogelijk, zoals waterkwaliteitsmonitoring
en inspectie van kunstwerken. Met drones kan het watersysteem
beter in beeld worden gebracht, wat uiteindelijk de waterkwaliteit ten
goede zal komen. Een beeld van de huidige inzetbaarheid van onderwaterdrones
en toekomstige ontwikkelingen.

 

Authors: Floris Boogaard (Tauw, Hanzehogeschool Groningen), Rui de Lima (INDYMO), Daru Setyorini (ECOTON),
Martin Beusekom (Blue Eagle Consultancy), Christa Nooy (Indonesia Specialist Community Involvement),
Rutger de Graaf (Hogeschool Rotterdam, INDYMO)

Download: ac790c043a7f99cd82b5303dc205b116

Description: Een consortium van Indonesische en Nederlandse organisaties is begonnen met een grootschalig internationaal onderzoek naar oplossingen voor de slechte kwaliteit van oppervlaktewater in Soerabaja, Indonesië. Hierbij worden innovatieve participatieve meetmethoden ingezet, waaronder aquatische drones en apps. De eerste resultaten wijzen uit welke vervuilende bronnen en locaties aangepakt moeten worden: industrieel en huishoudelijk afvalwater. Tijdens de interactie bij de metingen is gewerkt aan verhoging van de betrokkenheid van de stakeholders, educatie en bewustwording. Tijdens deze internationale kennisuitwisseling over waterkwaliteitsverbetering worden de ‘lessons learned’ uit de Nederlandse topsector water toegepast, een van de belangrijkste exportproducten van Nederland.

Authors: Paul van Eijk (Hogeschool Van Hall Larenstein/CEW), Rui de Lima (INDYMO), Jan Roelsma (Wetterskip Fryslân), Lisette van der Berg (Hogeschool Van Hall Larenstein)

Download: a63f4b8e7960e6323c8d02c2a5d1e4e7

Description: Wetterskip Fryslân, Hogeschool Van Hall Larenstein en Indymo voeren onderzoek uit naar de bruikbaarheid en toepassingsmogelijkheden van onderwaterdrones in het werkveld. Er zijn veel toepassingen mogelijk, zoals waterkwaliteitsmonitoring en inspectie van kunstwerken. Met van drones kan het watersysteem beter in beeld worden gebracht, wat uiteindelijk de waterkwaliteit ten goede zal komen. Ondanks de grote inzetbaarheid van drones zijn er nog veel wensen om ze beter te laten aansluiten bij de eisen in het veld.

Download: fb9bfaf32fd65af29bd91e1af8289f1a

Tijdens onderzoek naar de waterkwaliteit onder drijvende bouwwerken, is onder het drijvend paviljoen in de Rotterdamse Rijnhaven een onverwacht ecosysteem aangetroffen. Met een videocamera op een onderwaterdrone zijn filmbeelden gemaakt en is de waterkwaliteit gemeten. Op de onderwaterbeelden zijn wier, mosselen en schelpdieren te zien die zich aan de onderkant van het drijvend platform hebben vastgezet; visjes zwemmen er doorheen.

Download: 8e195ba8c78301cc2fad8eb846568fed

Wat hebben New York, Rotterdam en de andere deltametropolen in de wereld gemeen? De strijd tegen het water. Deltametropolen moeten constant slimme oplossingen zoeken om in te spelen op de effecten van de klimaatverandering. Daarnaast moeten ze alternatieven bedenken voor de stedelijke havengebieden die wegens het wegtrekken van de havenactiviteiten ineens veel ruimte over hebben. Deze gebieden langs het water zijn nieuwe plekken om te wonen, werken en spelen.

 

Authors: Floris Boogaard (INDYMO /Hanzehogeschool Groningen/Tauw), Rui de Lima (INDYMO), Jasper Stroom (Waternet)

Bij onderzoek naar ecologie en waterkwaliteit kunnen onderwaterdrones worden toegepast. De
drones, uitgerust met diverse sensoren en camera’s, blijken een waardevolle toevoeging aan de
reguliere steekmonsters die de ecologische kwaliteit van het waterlichaam beoordelen. Uit de eerste
resultaten blijkt dat de drones goed kunnen worden ingezet voor het verkrijgen van een 3D-beeld van
de waterkwaliteit en ecologie in de plas, zoals bij de pilot in de Sloterplas in Amsterdam. Na
verschillende pilots met diverse waterschappen zullen onderwaterdrones in de toekomst bij
watergerelateerde onderzoeksprojecten voor meerdere doeleinden worden gebruikt.

Download: 9bf8ab002a20c10beb204d1457f3a608

Download: c0ac8e93d846455b513d5a544b3f849b

Description: De informatie uit dit rapport is gebruikt in de watersysteemanalyse van de Sloterplas:
“Sloterplas: Systeemanalyse, blauwalgbestrijding en maatregelen KRW”, bestaande uit een
hoofdrapport (Stroom 2016a) en een achtergrondrapport (Stroom 2016b).
De Sloterplas voldoet niet aan de ecologische normen voor de Kaderrichtlijn Water
(KRW). Vanaf 2012 is het water wel veel helderder geworden en de
blauwalgnormen voor de Zwemwaterrichtlijn (ZWR) werden in 2012-2015 minder
vaak overschreden. Rond diezelfde periode is in de plas een grote hoeveelheid
invasieve quaggamossels verschenen. Deze mossels filtreren het water.
Doelstellingen
De doelstellingen van dit rapport zijn om voor de Sloterplas:
1. kwantitatief te onderbouwen dat de quaggamossels de systeemomslag van
troebel blauwalgwater naar veel helderder water hebben veroorzaakt
2. een prognose te geven van de ontwikkeling van de invloed van de
quaggamossels op de aquatische ecologie
3. aanbevelingen te doen voor potentiële maatregelen die gebruikmaken van de
mossels.
Dit rapport is gebaseerd op een literatuuronderzoek en op onderzoek naar de
populatiegrootte en -samenstelling van de mossels in de Sloterplas.
Resultaten
1. In de Sloterplas was (juni 2015) de helft van het plasoppervlak op de bodem
bedekt met gemiddeld 5500 /m2 quaggamossels. Ze lagen aan de randen van
de plas tot 12.5 m diepte. Deze dichtheden kunnen in 4-10 dagen het
plasvolume filtreren. Om blauwalgenbloeien te voorkomen is een verblijftijd van
ongeveer 10 dagen nodig. Dat maakt het zeer aannemelijk dat het heldere
water is veroorzaakt door de quaggamossels, temeer daar de zeer hoge
nutriëntenbelasting op de plas niet is verminderd.
2. Het vergt onderzoek om een goede prognose te kunnen geven van de
ontwikkeling van de quaggapopulatie en van de te verwachten waterkwaliteit
en aquatische ecologie op de langere termijn. Dit onderzoek is ook nodig om de
potentiële KRW- en ZWR-maatregelen die gebruikmaken van quaggamossels
(zie onder 3) nader te kunnen uitwerken. Aanbevolen wordt dit onderzoek uit
te voeren. Belangrijke aspecten hierbij zijn de predatiedruk op de
quaggamossels door watervogels en vissen en de graasdruk van de
quaggamossels op (blauw)algen. Deze graasdruk is onder andere gerelateerd
aan voedselselectie door de mossels, verticale migratie van blauwalgen,
overwintering op het sediment van blauwalgen en stikstoflimitatie. Het midden
van de plas, waar geen graasdruk van quaggamossels is, kan als kraamkamer
voor (blauw)algen fungeren. Een onderzoeksvraag is dan ook in hoeverre de
quaggamossels aan de randen van de plas de algenproductie in deze
kraamkamer teniet kunnen doen. Wat betreft de ontwikkeling van
onderwaterplanten is het van belang te onderzoeken of een dichte
mosselbedekking op het sediment de kieming en ontwikkeling van waterplanten
kan belemmeren.
26 april 2016 – Quaggamossels en hun dominantie in de Sloterplas – J.M. Stroom 4/69
3. Aanbevolen wordt om als KRW-onderzoeksmaatregel in te zetten op het
vergroten van de invloed van de quaggamossels. Dit kan door het uitbreiden
van de hoeveelheid ondiep substraat (bijvoorbeeld aan drijvers), vooral boven
de diepe delen in het midden van de plas.
Aanbevolen wordt om als ZWR-onderzoeksmaatregel in te zetten op een
“quaggafilter” bij de zwemwaterlocatie Varkensbaai, bestaande uit aan drijvers
hangende netten met quaggamossels. Dit kan het zwemstrand extra
bescherming bieden tegen horizontaal (door wind gedreven) transport van
blauwalgen en tegen lokale productie van blauwalgen.

 

 

Menig jongenshart gaat er sneller van kloppen: drones, ofwel onbemande
luchtvaartuigen. Ook in de watersector wordt volop geëxperimenteerd
met deze toestellen. Welke toepassingsmogelijkheden zijn al bedacht? En
welke kunnen we nog verwachten?

Download: 34783437a14c9d3c8f054f41dad2e7d7

 

Drone Pilot School

It started with success at VHL (University of Applied Sciences located in Leeuwarden, the Netherlands) last year, in close cooperation with CIV Water*, Nordwin College* en MBO life sciences, and will therefor continue in 2018 and be further up-scaled to Asia and Africa. Trainees will get their underwater drone diploma after showing awareness to water quality issues and being able to apply innovating monitoring methods as underwater drones with sensors and cameras. The training also consist of: writing a measurement plan, data analysis and translating this data to concrete action plan to rehabilitate polluted water systems. 

Presentations

Impact of Floating Structures

Foris Boogaard presented a research work about the impacts of floating structures on water quality, during the “Deltas in times of climate change II” conference, in Rotterdam (September 2014). The session was entitled “Creating floating cities: A dream or a new perspective for the future of the planet?” and was chaired by INDYMO and Deltasync director: Rutger de Graaf.

 

Vladislav Sazonov presented the outcomes of his internship in Deltasync, during a Delta Academy on December 2014. He worked on the impacts of floating structures on water quality project, but also on theBlue Revolution.

Applications of underwater drones

Rutger de Graaf (Indymo) and Hermen Klomp (Hunze en Aa’s) presented an overview of several case studies of the use of drones for the monitoring of water systems. The presentations were part of the STOWA thematic Technology Approval Group (TAG) session. The event took place on the 5th of April 2016, in Amersfoort and it had as a goal the introduction of innovative technologies to the Dutch Water Authorities. 

http://www.isleutilities.com/events/water-systems-tag