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Purifying manure effluents with duckweed
Timmerman, M. ; Hoving, I.E. - \ 2016
Wageningen UR Livestock Research (Livestock Research rapport 942) - 27 p.
animal manures - effluents - lemna - aquatic weeds - feeds - nutrients - ingredients - animal feeding - animal nutrition - waste water - biogas - biomass production - cultivation - biobased economy - dierlijke meststoffen - afvoerwater - schadelijke waterplanten - voer - voedingsstoffen - ingrediënten - diervoedering - diervoeding - afvalwater - biomassa productie - teelt
The objective of this study was to perform a short literature survey to provide information about purifying manure effluents with duckweed with regard to varieties, cultivation, harvesting methods, utilization and valorisation of duckweed. The results of the study show that duckweed can be used to recuperate nutrients from manure effluents and that the concerning duckweed can be utilized as a source of feed, energy and ingredients
Concept-afwegingskader beheersing invasieve oever- en waterplanten
Dijk, C.J. van; Riemens, M.M. - \ 2014
Amersfoort : Stowa (Rapport / STOWA 2014-20) - ISBN 9789057736520 - 39
waterlopen - invasieve exoten - schadelijke waterplanten - plagenbestrijding - inventarisaties - streams - invasive alien species - aquatic weeds - pest control - inventories
Uitheemse, woekerende oeverplanten en waterplanten kunnen voor veel problemen zorgen in de waterbeheersing. Dan is bestrijding gewenst. Dit rapport is een eerste stap in de ontwikkeling van een volwaardig afwegingskader voor het kiezen van de meest adequate bestrijdingsmethode. Bestrijding van uitheemse, woekerende oever- en waterplanten, zoals de Waterwaaier (Cabomba) en de Grote waternavel, vergen vaak grote inspanningen van waterbeheerders. Er zijn voorbeelden waarin deze uitheemse soorten dermate snel watergangen koloniseren, dat snelle bestrijding vereist is. De verwachting is dat problemen met uitheemse soorten planten (en dieren) in watergangen in de toekomst gaan toenemen. Om de veiligheid en de functionaliteit van waterinfrastructuur te kunnen garanderen, is bestrijding en/of beheersing van invasieve uitheemse soorten noodzakelijk.
Meer kroos in de toekomst, maar doen we er iets aan?
Peeters, E.T.H.M. ; Heuts, P. ; Netten, J.J.C. - \ 2013
H2O : tijdschrift voor watervoorziening en afvalwaterbehandeling 46 (2013)7/8. - ISSN 0166-8439 - p. 38 - 39.
oppervlaktewaterkwaliteit - schadelijke waterplanten - waterbeheer - surface water quality - aquatic weeds - water management
Hogere temperaturen zullen leiden tot meer kroosvorming, wat de kwaliteit van het oppervlaktewater negatief beïnvloedt. Het sterker verminderen van de toevoer van voedingsstoffen (nutriënten) in het water, kan de effecten van klimaatverandering neutraliseren. Veel waterbeheerders beschouwen de aanpak van kroos niet als topprioriteit. Meestal beperkt die aanpak zich tot het bestrijden van de symptomen en blijven de oorzaken buiten schot.
Meer en langduriger kroos bij veranderend klimaat
Peeters, E.T.H.M. ; Heuts, D.P.H.M. ; Netten, J.J.C. - \ 2013
H2O online 2013 (2013)28 aug.
oppervlaktewaterkwaliteit - schadelijke waterplanten - waterbeheer - klimaatverandering - surface water quality - aquatic weeds - water management - climatic change
Hogere temperaturen zullen leiden tot meer kroosvorming, wat de kwaliteit van het oppervlaktewater negatief beïnvloedt. Het sterker verminderen van de toevoer van voedingsstoffen (nutriënten) in het water, kan de effecten van klimaatverandering neutraliseren. Veel waterbeheerders beschouwen de aanpak van kroos niet als topprioriteit. Meestal beperkt die aanpak zich tot het bestrijden van de symptomen en blijven de oorzaken buiten schot.
Bestrijding Grote Waternavel, Waterteunisbloem en Parelvederkruid : resultaten van een kasproef naar de effectiviteit van branden en frequente manuele bestrijding op de groei van H. ranunculoides, L. grandiflora en M. aquaticum bij verschillende nutriëntenniveaus van de bodem
Michielsen, J.G.P. ; Riemens, M.M. - \ 2012
Wageningen : Plant Research International, Business Unit Agrosysteemkunde - 47
schadelijke waterplanten - herbiciden - mechanische bestrijding - waterlopen - plagenbestrijding - veldproeven - kostenanalyse - aquatic weeds - herbicides - mechanical control - streams - pest control - field tests - cost analysis
Grote waternavel, Parelvederkruid en Waterteunisbloem zijn invasieve exoten die in zowel Vlaanderen als Nederland voor problemen zorgen. De belangrijkste problemen zijn wateroverlast en schade aan inheemse soorten. De waterschappen en provincies die belast zijn met het beheer van de watergangen zijn jaarlijks zeer veel tijd en geld kwijt aan het verwijderen van deze soort. Machinale verwijdering veroorzaakt fragmentatie en daarmee verspreiding en toepassing van herbiciden is in de regio niet mogelijk. Zowel de verwijdering als afvoer zijn duur en overschrijden ruimschoots de reguliere kosten voor het beheer
Invasieve exoten in Vlaanderen en Nederland : resultaten uit het Invexo-project en aanbevelingen voor verbetering van de exotenaanpak
Burg, W.J. van der; Lotz, L.A.P. - \ 2012
Wageningen : Plant Research International - 128
flora - fauna - schadelijke waterplanten - invasieve soorten - inventarisaties - natuurbeleid - samenwerking - zuid-nederland - vlaanderen - aquatic weeds - invasive species - inventories - nature conservation policy - cooperation - south netherlands - flanders
De casus-overkoepelende werkgroep „Voorstel Beleid en Samenwerking‟ inventariseerde de mogelijkheden om beleid in de verschillende regio‟s op elkaar af te stemmen en samenwerking te stimuleren. De resultaten van deze werkgroep staan in dit rapport. Invasieve exoten kennen geen grenzen. Daarom is het nodig dat gemeenten, provincies, regio‟s en landen samenwerken om probleemsoorten te bestrijden en te voorkomen. De Europese Unie stimuleert die grensoverschrijdende aanpak van invasieve exoten. 24 partners uit Vlaanderen en Zuid-Nederland deden mee aan het Invexo-project (Europees Interreg-project IV A, 2009-2012). In dit project werden vier probleemsoorten of soortengroepen in Vlaanderen en/of Zuid-Nederland aangepakt: grote waternavel (en ook waterteunisbloem en parelvederkruid), Amerikaanse vogelkers, stierkikker en zomerganzen.
Exotische waterplant cabomba groeit explosief
Vliet, A.J.H. van - \ 2009
Nature Today 2009 (2009)1-5-2009.
cabomba - geïntroduceerde soorten - invasies - nieuwe soorten - verspreiding - schadelijke waterplanten - nadelige gevolgen - bestrijdingsmethoden - introduced species - invasions - new species - dispersal - aquatic weeds - adverse effects - control methods
De cambomba of waterwaaier is een waterplant die oorspronkelijk uit Zuid-Amerika komt. De plant wordt veel als aquariumplant gebruikt en sinds 1986 is hij voor het eerst in het Nederlandse oppervlaktewater aangetroffen
Deskstudie biologische bestrijding van invasieve exotische oever- en wateronkruiden in Nederland
Kempenaar, C. ; Franke, A.C. ; Lotz, L.A.P. - \ 2009
Wageningen : Plant Research International (Nota / Plant Research International 589) - 24
rivieroeverbeplantingen - schadelijke waterplanten - onkruidbestrijding - biologische bestrijding - geïntroduceerde soorten - invasie - nederland - aquatische ecosystemen - riverside plantations - aquatic weeds - weed control - biological control - introduced species - invasion - netherlands - aquatic ecosystems
In dit rapport wordt een overzicht gegeven van biologische onkruidbestrijding in het algemeen, en ontwikkelingen op het gebied van biologische bestrijding van elf belangrijke exotische oever- en wateronkruiden in Nederland in het bijzonder. Twee relevante casussen worden nader belicht: de graskarper en de waterhyacint
The effects of a pesticide mixture on aquatic ecosystems differing in trophic status: responses of the macrophyte Myriophyllum spicatum and the periphytic algal community
Wendt-Rasch, L. ; Brink, P.J. van den; Crum, S.J.H. ; Woin, P. - \ 2004
Ecotoxicology and Environmental Safety 57 (2004)3. - ISSN 0147-6513 - p. 383 - 398.
aquatisch milieu - waterplanten - schadelijke waterplanten - asulam - herbicidenmengsels - lambda-cyhalothrin - metamitron - onbedoelde effecten - niet-doelorganismen - pesticidenresiduen - trofische graden - onkruiden - aquatic environment - aquatic plants - aquatic weeds - herbicide mixtures - nontarget effects - nontarget organisms - pesticide residues - trophic levels - weeds - fresh-water microcosms - insecticide dursban(r) 4e - phytoplankton succession - pyrethroid insecticides - fungicide carbendazim - phosphorus release - final conclusions - primary producers - model-ecosystems - zooplankton
The effects of a pesticide mixture (asulam, fluazinam, lambda-cyhalothrin, and metamitron) on aquatic ecosystems were investigated in 20 outdoor aquatic microcosms. Ten of the microcosms simulated mesotrophic aquatic ecosystems dominated by submerged macrophytes (Elodea). The others simulated eutrophic ecosystems with a high Lemna surface coverage (Lemna). This paper describes the fate of the chemicals as well as their effects on the growth of Myriophyllum spicatum and the periphytic algal community. In the Elodea-dominated microcosms significant increase in the biomass and alterations of species composition of the periphytic algae were observed, but no effect on M. spicatum growth could be recorded in response to the treatment. The opposite was found in the Lemna-dominated microcosms, in which decreased growth of M. spicatum was observed but no alterations could be found in the periphytic community. In the Elodea-dominated microcosms the species composition of the periphytic algae diverged from that of the control following treatment with 0.5% spray drift emission of the label-recommended rate (5% for lambda-cyhalothrin), while reduced growth of M. spicatum in the Lemna-dominated microcosms was recorded at 2% drift (20% for lambda-cyhalothrin). This study shows that the structure of the ecosystem influences the final effect of pesticide exposure.
A simple method for analysing the effects of algae on the growth of Lemna and preventing algal growth in duckweed bioassays
Szabo, S. ; Roijackers, R.M.M. ; Scheffer, M. - \ 2003
Archiv für Hydrobiologie 157 (2003)4. - ISSN 0003-9136 - p. 567 - 575.
schadelijke waterplanten - toxicologie - biotesten - ecotoxicologie - aquatic weeds - toxicology - bioassays - ecotoxicology - fresh-water macrophytes - common duckweed - waste-water - toxicity - ph
A simple novel method for indoor culture experiments with small floating water plants, such as Lemnaceae, is described. Experiments demonstrate that the method allows for longer lasting culture experiments with Lemna, avoiding algal growth and self-shading of fronds by overcrowding. This is achieved by enclosing the Lemna fronds in tubes, which are replaced during growth by tubes of increasing diameter. The RGR of Lemna reached optimal values (RGR > 0.3 day-1) when not hampered by algal growth. In competition experiments with algae growing outside the tubes and Lemna inside the tubes, the growth of the fronds decreased dramatically; chlorophyll content of the fronds was 91-97% less and RGR 29-55 % less. This method allows for multifactorial experiments, handling up to 100 experimental units per researcher. This paves the road to competition experiments among and between water plants for light, nutrients and space
The smell of water : grazer-induced colony formation in Scenedesmus
Lürling, M. - \ 1999
Agricultural University. Promotor(en): W.J. Wolff; E. van Donk. - S.l. : s.n. - ISBN 9789058080462 - 270
scenedesmus - daphnia - aquatische gemeenschappen - waterorganismen - fytoplankton - schadelijke waterplanten - spreiding - ecologie - begrazing - onderzoek - aquatic communities - aquatic organisms - phytoplankton - aquatic weeds - spread - ecology - grazing - research - cum laude
<p>In aquatic systems, the phytoplankton - zooplankton relation is of major importance because it is the first step in the pelagic food chain. It is well known that zooplankton feed with a highly variable success on phytoplankton, primarily owing to algal characteristics such as size, shape, cell wall texture, nutritional quality and toxicity. Algae are present in a broad variety of shapes and may express an enormous variability in their morphology, physiology and behavior depending on environmental variables. Because algae depend on solar energy they have to remain in the upper water layers as long as possible. Moreover, they have to compete with other algae for dissolved nutrients. This means that in an aquatic environment selection pressure exists for small organisms since these have the most efficient uptake of nutrients and light and lowest sinking losses. By contrast, mortality through grazing by an entire assemblage of protozoan and metazoan grazers will exert a strong selection for traits that reduce this mortality through grazing. An effective way to resist grazing is by a dramatic increase in size. However, this confronts the algae with conflicting allometries of selection pressures.</p><p>Since algae are small relative to their predatory enemies, they may not survive an encounter with a grazer. Therefore, it may be profitable to detect a grazer before they encounter each other in order to elicit a defensive strategy. In a predictable environment temperature and day length could be good predictor of danger. However, in aquatic systems, grazing fluctuates considerably on temporal and spatial scales and chemical cues may be used instead. All organisms exchange constantly chemicals with their environment and those chemicals that are essential in the biology of the grazer and are detectable by the algae may prove potential indicators of danger. They convey information and are referred to as infochemicals. This thesis focuses on the role of infochemicals in the interaction between algae and zooplankton, with emphasis on the <em>Scenedesmus</em> (algae) - <em>Daphnia</em> (waterflea) relation.</p><p>In the presence of filtered medium from a <em>Daphnia</em> culture, the non-spiny <em>Scenedesmus acutus</em> formed numerous eight-celled colonies (coenobia) (Chapter 2). However, in control populations, i.e. in the absence of <em>Daphnia</em> -infochemical, <em>S. acutus</em> remained unicellular and formed only four-celled colonies when cultures reached stationary phase. The induced colony formation appeared reversible as eight-celled colonies gradually disappeared from the treated populations.</p><p>A prerequisite for further exploration of the phenomenon of <em>Daphnia</em> -induced colony formation is the development of a reliable biotest (Chapter 3). Inoculum algal density, carbon availability and filter-type are some of the factors that affected the <em>Daphnia</em> -induced colony formation. Analysis of filter extractables revealed that at least two detergents might cause <em>S. acutus</em> to shift rapidly from a completely unicellular population to one dominated with colonies. The production of the <em>Daphnia</em> -infochemical is related to the amount of food processed by the animals. Starved animals or animals fed with ingestible but non-digestible beads were ineffective in inducing colonies. Neither algal homogenates nor auxins and several organic carbon sources have colony inducing activity. The infochemical does seem to originate from the <em>Daphnia</em> -food interaction, or better from the grazer-algal food interaction as several herbivorous zooplankters were able to induce colonies in <em>S. acutus</em> , whereas carnivorous zooplankton and fish were ineffective (Chapter 3). Simple excretion products, such as ammonia and urea alone or in combination with organic carbon sources were ineffective as colony inducing agents (Chapters 3 & 4).</p><p><em>Scenedesmus</em> plasticity has, however, not only been shaped by the activity of grazers, but also by other selective forces. Several factors are known that may influence the growth and morphological development in <em>Scenedesmus</em> and among them nutrient availability (Chapter 4) and temperature (Chapter 5) are important ones. In culture, with relatively high algal densities carbon limitation may occur. The availability of inorganic carbon appeared ineffective in inducing colonies, but had a clear effect on cell size. Neither N- nor P-limitation resulted in the formation of numerous, eight-celled coenobia. In general, under nutrient limitation cultures were dominated by unicells. However, despite the limitation, by adding <em>Daphnia</em> water, colonies still could be induced. One of the criticisms on use of artificial growth media is the excessive amount of nutrients in most of them. However, using media of various strengths showed no differences in morphological appearance of <em>S. acutus</em> , both in the absence and presence of <em>Daphnia</em> water.It appears that as long as cell division is not hampered grazer-induced colony formation may occur.</p><p>Temperature not only affected growth, but also the morphological development in <em>S. acutus</em> (Chapter 5). At low temperatures growth was reduced, but cell- and colony size increased. Under a broad range of temperatures from 9° to 29°C, the addition of <em>Daphnia</em> water significantly increased the proportion of eight-celled coenobia. The smaller size at higher temperature supports the hypothesis of a trade-off between sinking and size.</p><p>An analysis of potential costs associated with grazer-induced colony formation was initially directed on metabolic costs (Chapter 6). However, no reductions in growth and photosystem II efficiency were detected in induced colonies. Higher sinking losses of induced colonial <em>Scenedesmus</em> populations were measured. Hence, costs may be assigned to enhanced sinking out of the euphotic zone into darker and colder water layers, thereby significantly reducing growth rates. The strategy may, however, not be completely lethal, as <em>Scenedesmus</em> is known to be capable of surviving for prolonged periods on the sediments.</p><p>One of the prerequisites for interpreting the grazer-induced colony formation as an induced defense is that the response has to be effective in reducing mortality through grazing. In Chapter 7, the grazing success of several zooplankton species, such as the rotifers <em>Keratella</em> and <em>Brachionus</em> and the cladocerans <em>Bosmina</em> , <em>Ceriodaphnia</em> and <em>Daphnia</em> , was analyzed. Food intake was reduced in all smaller grazers, but not in the largest <em>Daphnia</em> species. Moreover, growth of the small <em>Daphnia cucullata</em> was reduced when offered colonial <em>S. acutus</em> . These reductions appeared not the result of an altered biochemical composition of induced colonies.</p><p>So far, the effect of grazing-associated infochemicals had only been examined for the non-spiny <em>S. acutus</em> . In Chapter 8, 23 different <em>Scenedesmus</em> strains, 9 different other chlorophytes, 2 diatom species and 5 strains of cyanobacteria were investigated. In 35% of the <em>Scenedesmus</em> a positive response to the addition of <em>Daphnia</em> water was observed. Most responding appeared the non-spiny strains, i.e. 64% in contrast to the 4% for spined <em>Scenedesmus</em> . Not only is the trait colony formation only one of the potential defensive traits, it also appeared that the biotest was only suited for examining non-spiny <em>Scenedesmus</em> .</p><p>The grazer-induced colony formation appeared not to be restricted to the genus <em>Scenedesmus,</em> since two <em>Coelastrum</em> strains were responsive too. Also in the diatom <em>Synedra</em> and the cyanobacterium <em>Microcystis</em> cell size was increased in the presence of <em>Daphnia</em> water. Moreover, the latter showed a tendency to higher toxin levels when cultured in the presence of medium from a <em>Daphnia</em> culture (Chapter 8).</p><p>Another phenomenon often observed in the presence of live <em>Daphnia</em> , is the aggregation of live cells onto fecal pellets (Chapter 8). These large aggregates will undoubtedly be inedible to grazers and may be an additional process affecting the energy flow from algae to their consumers.</p><p>In Chapter 9, experiments were performed to evaluate the ability of <em>Daphnia</em> to locate algae by means of chemical cues. No evidence for such a mechanism was detected. However, the animals did seem to avoid water with odors from congeners. Moreover, water from crowded <em>Daphnia</em> cultures had clear effects on growth and reproduction in two <em>Daphnia</em> species and may have an effect on the phytoplankton-grazer interaction.</p><p>Summarizing the various experiments described in this thesis, the phenomenon of grazer-induced colony formation in <em>Scenedesmus</em> can be interpreted as an inducible defense at the expense of higher sinking losses. The phenomenon is not restricted to <em>Scenedesmus</em> and because of the enormous plasticity in phytoplankton, numerous species may eventually turn out not only to respond to abiotic but to biotic agents as well.</p>
Flow resistance and hydraulic capacity of water courses with aquatic weed growth; Part 2
Querner, E.P. - \ 1997
Irrigation and Drainage Systems 11 (1997)2. - ISSN 0168-6291 - p. 171 - 184.
onkruidbestrijding - kanalen - kanalen, klein - waterwegen - schadelijke waterplanten - hydrodynamica - vloeistoffen (liquids) - vloeistoffen (fluids) - stroming - rivieren - waterlopen - water - afvoer - drainage - sloten - hydrologie - modellen - analogen - weed control - canals - channels - waterways - aquatic weeds - hydrodynamics - liquids - fluids - flow - rivers - streams - discharge - ditches - hydrology - models - analogues
A model to estimate timing of aquatic weed control in drainage canals; Part 1
Querner, E.P. - \ 1997
Irrigation and Drainage Systems 11 (1997)2. - ISSN 0168-6291 - p. 157 - 169.
onkruidbestrijding - kanalen - kanalen, klein - waterwegen - schadelijke waterplanten - drainage - sloten - rivieren - waterlopen - water - afvoer - modellen - nederland - weed control - canals - channels - waterways - aquatic weeds - ditches - rivers - streams - discharge - models - netherlands
In many parts of the Netherlands a dense network of watercourses is necessary to drain the land. A related aspect is thechanging transport capacity of the water courses due to thegrowth of aquatic plants in the growing season. In turn thisphenomenon requires aquatic weeds to be controlled by waterboards in order to maintain the water course's required capacity.

The procedure outlined in this paper can be used to determinethe frequency of weed control based on hydrological andhydraulic conditions. The drainage from groundwater gives anexpected variation in discharge over the growing season. Thepermissible flow rate is governed by both the growth of weedsand the permissible water levels in the water course. Weedcontrol is necessary during the growing season when theexpected discharge is more than the permissible flow rate. Thisprocedure has been incorporated in the model MWW(Maintenance of Water courses by Water boards). An examplehow to use MWW is given.
De stromingsweerstand en de berekening van de afvoer in begroeide waterlopen
Querner, E.P. - \ 1995
Het Waterschap 80 (1995)9. - ISSN 1380-4251 - p. 350 - 356.
schadelijke waterplanten - kanalen - kanalen, klein - sloten - stroming - vloeistoffen (fluids) - hydrodynamica - vloeistoffen (liquids) - onderhoud - waterwegen - onkruidbestrijding - aquatic weeds - canals - channels - ditches - flow - fluids - hydrodynamics - liquids - maintenance - waterways - weed control
Maaionderhoud in waterlopen is een belangrijke taak van waterschappen. Het vermogen om water af te voeren is afhankelijk van de aanwezigheid van waterplanten en oevervegetatie en bepaalt het tijdstip van onderhoud. Met behulp van de stromingsweerstanden de mate van begroeiing met water- en oevervegetatie wordt het debiet in een waterloop berekend. Het dwarsprofiel van een waterloop wordt opgedeeld in een onbegroeid en een begroeid gedeelte. Voor het onbegroeide deel is met behulp van metingen in het veld en in een modelgoot een stromingsweerstand afgeleid. De stroming door het begroeide deel is te verwaarlozen. Het oppervlak dat door waterplanten wordt ingenomen, is gedurende het groeiseizoen gemeten.
Vaststellen maaionderhoud in waterlopen; hydrologische benadering
Querner, E.P. - \ 1995
Het Waterschap 80 (1995)4. - ISSN 1380-4251 - p. 170 - 175.
analogen - schadelijke waterplanten - kanalen - kanalen, klein - afvoer - sloten - hydrologie - onderhoud - modellen - Nederland - rivieren - waterlopen - water - waterwegen - onkruidbestrijding - analogues - aquatic weeds - canals - channels - discharge - ditches - hydrology - maintenance - models - Netherlands - rivers - streams - waterways - weed control
Maaionderhoud in waterlopen is nodig om de watertransportfunctie ervan te waarborgen. Het benodigde maaionderhoud in waterlopen is vanuit hydrologisch oogpunt berekend. De belangrijkste aspecten hierbij zijn: verwachte afvoer, dimensies van de waterloop, drooglegging, stromingsweerstand, en groei van water- en oevervegetatie. Voor het berekenen van tijdstip en frequentie van onderhoud zijn de verwachte afvoeren berekend met een eendimensionaal grondwatermodel. Als de verwachte afvoer groter is dan het toelaatbare debiet, is onderhoud nodig. Het onderhoud is berekend voor twee waterlopen in Twente. De methode biedt de waterschappen de mogelijkheid om het maaibeheer te verantwoorden of te verminderen.
Aquatic weed control within an integrated water management framework
Querner, E.P. - \ 1993
Agricultural University. Promotor(en): R.A. Feddes; J.J. Bogardi. - S.l. : [s.n.] - ISBN 9789054851226 - 204
sloten - onderhoud - rivieren - waterlopen - kanalen - water - afvoer - hydrodynamica - vloeistoffen (liquids) - vloeistoffen (fluids) - stroming - kanalen, klein - onkruidbestrijding - waterwegen - schadelijke waterplanten - grondwater - oppervlaktewater - grondwaterspiegel - hydrologie - modellen - analogen - onderzoek - Nederland - watergebruik - ditches - maintenance - rivers - streams - canals - discharge - hydrodynamics - liquids - fluids - flow - channels - weed control - waterways - aquatic weeds - groundwater - surface water - water table - hydrology - models - analogues - research - Netherlands - water use
<p>Aquatic weed control, carried out by the water boards in the Netherlands, is required to maintain sufficient discharge capacity of the surface water system. Weed control affects the conditions of both surface water and groundwater. The physically based model MOGROW was developed to simulate the flow of water in the unsaturated zone, the saturated zone and the water courses in an integrated manner. The model was verified with field data on groundwater levels, discharges, moisture storage in the root zone and evapotranspiration in the Hupselse Beek catchment.<p>The time and frequency of weed control during summer were determined using data on weed growth, flow resistance and discharges. This study was carried out in the Poelsbeek and Bolscherbeek catchments located in the east of the Netherlands. Weed obstruction was measured in nine water courses of these catchments. The boundary roughness coefficient κ <sub><font size="-2">M</font></sub><em></em> was calculated from field data and laboratory experiments. The κ <sub><font size="-2">M</font></sub><em></em> varied for the unobstructed part of the cross-section between 30-34 m <sup><font size="-2">1/3</font><strong>.</strong></SUP>s <sup><font size="-2">-1</font></SUP>. A numerical model was used to determine the velocity distribution in a cross-section of a water course. This calculated velocity distribution resulted also in κ <sub><font size="-2">M</font></sub><em></em> values of the same order. The minimally required weed control was estimated using the data on weed obstruction, flow resistance and estimates of expected discharges. These expected discharges for the summer period were calculated for three water table fluctuation classes, using a one-dimensional groundwater model. Comparing the expected discharges and the permissible flow rates for a water course, gives the required periods of weed control.<p>Weed control strategies were evaluated for the Poelsbeek and Bolscherbeek area using the model MOGROW. Results of the modelling experiments are the occurrence of high surface water levels, high groundwater levels and high stream flow velocities. In a cost-benefit analysis the cost of weed control and the damage for pasture (in terms of financial losses) were considered. Seven simulation years with varying wet conditions in summer were selected. The financial loss resulting from one clearing at the end of summer, was too high for only one of these years. The multi-objective decision method ELECTRE II enabled the ecological impact to be incorporated in the evaluation. The method identified weed control strategies that are most favourable for agriculture or nature conservation.
Optimalisatie van het biologisch beheer van watergangen met behulp van graskarpers : voortgang 1989
Meulemans, J.T. ; Best, E.P.H. - \ 1991
Amsterdam etc. : AquaSence [etc.] (AquaSence rapport 91.0015) - 37
schadelijke waterplanten - kanalen - karper - kanalen, klein - cyprinidae - nederland - waterwegen - onkruidbestrijding - biologisch waterbeheer - aquatic weeds - canals - carp - channels - netherlands - waterways - weed control - biological water management
Het effect van maaitijdstip op de hergroei van drie soorten ondergedoken waterplanten : deelverslag van project 717 "Effecten van aard en frequentie van mechanisch onderhoud op de hergroei van submerse waterplanten"
Jacobs, F.H.H. ; Best, E.P.H. - \ 1990
Wageningen : CABO-DLO (CABO-verslag 140) - 51
aquatische gemeenschappen - schadelijke waterplanten - biomassa - kanalen - kanalen, klein - mechanische methoden - nederland - plantengemeenschappen - gewasbescherming - planten - waterwegen - onkruidbestrijding - aquatic communities - aquatic weeds - biomass - canals - channels - mechanical methods - netherlands - plant communities - plant protection - plants - waterways - weed control
Inventarisatie van onderzoek aan water- en oeverplanten in Nederland
Best, E.P.H. - \ 1988
Wageningen : CABO (CABO-verslag 83) - 154
aquatische gemeenschappen - schadelijke waterplanten - bibliografieën - kanalen - kanalen, klein - controlelijsten - inventarisaties - nederland - plantengemeenschappen - onderzoek - waterwegen - onkruidbestrijding - aquatic communities - aquatic weeds - bibliographies - canals - channels - checklists - inventories - netherlands - plant communities - research - waterways - weed control
Een overzicht wordt gegeven van in 1987 lopende onderzoeksprojecten met vermelding van contactpersoenen en publikaties van de laatste 5 jaar
Seasonal growth of Ceratophyllum demersum L., Elodea nuttallii (Planch) St. John and Potamogeton pectinatus in experimental ponds
Byrialsen, K. - \ 1988
Wageningen : CABO (CABO report / Centre for Agrabiological Research 97) - 16
schadelijke waterplanten - biomassa - ceratophyllaceae - groei - hydrocharitaceae - plantenontwikkeling - planten - potamogetonaceae - elodea nuttallii - potamogeton pectinatus - ceratophyllum demersum - aquatic weeds - biomass - growth - plant development - plants
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