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Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    A novel hybrid process of reverse electrodialysis and reverse osmosis for low energy seawater desalination and brine management
    Li, W. ; Krantz, W.B. ; Cornelissen, E.R. ; Post, J.W. ; Verliefde, A.R.D. ; Tang, C.Y. - \ 2013
    Applied Energy 104 (2013). - ISSN 0306-2619 - p. 592 - 602.
    ion-exchange membranes - environmental-impact - power-generation - swro process - river water - salinity - plant - performance - technology - difference
    This paper introduces a novel concept for a hybrid desalination system that combines reverse electrodialysis (RED) and reverse osmosis (RO) processes. In this hybrid process the RED unit harvests the energy in the form of electricity from the salinity gradient between a highly concentrated solution (e.g., seawater or concentrated brine) and a low salinity solution (e.g., biologically treated secondary effluent or impaired water). The RED-treated high salinity solution has a lower salt concentration and serves as the feed solution for the RO unit to reduce the pump work. The concentrated RO brine provides the RED unit a better high salinity source for the energy recovery compared to seawater. In addition, the concentration of the discharged brine can be controlled by the RED unit for improving the water recovery and minimizing the impact on the environment. Different configurations of the hybrid RED–RO processes are presented for a comparative study on the basis of mathematical modeling. Specifically, various operating conditions for the RED unit are investigated for better adaptation to the hybrid system. The variations of the total specific energy consumption and the discharge brine concentration for various hybrid modes are simulated to verify the conceptual designs. The modeling results indicate that the RED–RO hybrid processes could substantially reduce the specific energy consumption and provide a better control of the discharge brine concentration in comparison to conventional seawater desalination RO processes
    Exploring global Cryptosporidium emissions to surface water
    Hofstra, N. ; Bouwman, A.F. ; Beusen, A.H.W. ; Medema, G.J. - \ 2013
    Science of the Total Environment 442 (2013)1. - ISSN 0048-9697 - p. 10 - 19.
    activated-sludge treatment - parvum oocysts - giardia cysts - dairy calves - waste-water - healthy-adults - river water - production systems - nonpoint sources - climate-change
    The protozoan parasite Cryptosporidium is a major cause of diarrhoea worldwide. This paper presents the first model-based inventory with 0.5 by 0.5 degree resolution of global Cryptosporidium emissions for the year 2000 from humans and animals to surface water. The model is based on nutrient distribution modelling, because the sources and transport of oocysts and nutrients to the surface water are comparable. Total emissions consist of point source emissions from wastewater and nonpoint source emissions by runoff of oocysts in manure from agricultural lands. Results indicate a global emission of 3 × 10^17 oocysts per year, with comparable contributions from point and nonpoint sources. Hot-spot areas for point sources are big cities in China, India and Latin America, while the area with the largest nonpoint source emissions is in China. Uncertainties in the model are large. Main areas for further study are (i) excretion rates of oocysts by humans and animals, (ii) emissions of humans not connected to sewage systems, and (iii) retention of oocysts to determine surface water pathogen concentrations rather than emissions. Our results are useful to health organisations to identify priority areas for further study and intervention.
    Effect of additional charging and current density on the performance of Capacitive energy extraction based on Donnan Potential
    Liu, F. ; Schaetzle, O. ; Sales, B.B. ; Saakes, M. ; Buisman, C.J.N. ; Hamelers, H.V.M. - \ 2012
    Energy & Environmental Science 5 (2012)9. - ISSN 1754-5692 - p. 8642 - 8650.
    pressure retarded osmosis - water salinity difference - reverse electrodialysis - power-generation - gradient power - river water - sea
    The difference in the salt concentrations of river and seawater implies that wherever they mix, energy could be extracted from the salinity gradient. This is a renewable and clean means of generating energy that makes use of a natural process. Capacitive energy extraction based on the Donnan potential (CDP) is a promising technique for extracting this energy. We herein describe our investigation of the effect of additional charging on extraction behaviour using a forced current density. The study was conducted in a flow-through cell, using capacitive electrodes and ion exchange membranes. It is shown that increasing the accumulated charge in the system could be beneficial in terms of energy extraction. Furthermore, the addition of charge improved the power densities achieved. By charging at higher current densities and discharging at lower current densities, the performance of the system may be improved. The highest average power density achieved in this study was 0.205 +/- 0.006 W m(-2) (1.26 +/- 0.75 mW g(-1)). This was obtained using a charge of 6 C (4.62 C g(-1)), with a controlled constant current of 50 mA (38.5 mA g(-1) or 6.24 A m(-2)). Three main limiting factors to the performance of CDP were identified, namely (i) the voltage drop over time, caused by the self-discharge of the cell and the non-ideal behaviour of the membranes, (ii) the duration of the switching times and (iii) the loss over the internal resistance. Of these, the internal resistance was identified as being the most important parameter to be minimized in order to further improve the performances of CDP systems.
    Impact of Wire Geometry in Energy Extraction from Salinity Differences Using Capacitive Technology
    Sales, B.B. ; Burheim, O.S. ; Liu, F. ; Schaetzle, O. ; Buisman, C.J.N. ; Hamelers, H.V.M. - \ 2012
    Environmental Science and Technology 46 (2012)21. - ISSN 0013-936X - p. 12203 - 12208.
    pressure retarded osmosis - reverse electrodialysis - water desalination - renewable energy - power production - river water - electrodes - sea - deionization - gradients
    Energy extraction based on capacitive Donnan potential (CDP) is a recently suggested technique for sustainable power generation. CDP combines the use of ion-exchange membranes and porous carbon electrodes to convert the Gibbs free energy of mixing sea and river water into electric work. The electrodes geometry has a relevant impact on internal resistance and overall performance in CDP. In this work, we present the first effort to use wire shaped electrodes and its suitability for improving CDP. Analytical evaluation and electrical measurements confirm a strong nonlinear decrease in internal resistance for distances between electrodes smaller than 3 mm. We also demonstrated that we get more power per material invested when compared to traditional flat plate designs. These findings show the advantages of this design for further development of CDP into a mature technology.
    Tracing the spatial propagation of river inlet water into an agricultural polder area using anthropogenic gadolinium
    Rozemeijer, J. ; Siderius, C. ; Verheul, M. ; Pomarius, H. - \ 2012
    Hydrology and Earth System Sciences 16 (2012)8. - ISSN 1027-5606 - p. 2405 - 2415.
    watervoorziening - rivierwater - watertekort - zoet water - waterkwaliteit - landbouwgrond - tracer technieken - zeldzame aardelementen - nutriëntenstromen - water supply - river water - water deficit - fresh water - water quality - agricultural land - tracer techniques - rare earth elements - nutrient flows - quality - impact - irrigation - hydrology - nitrogen
    Diverting river water into agricultural areas or nature reserves is a frequently applied management strategy to prevent fresh water shortage. However, the river water might have negative consequences for chemical and ecological water quality in the receiving water bodies. This study aimed to obtain a spatial image of the diverted river water propagation into a hydrologically complex polder area, the polder Quarles van Ufford in The Netherlands. We used anthropogenic gadolinium (Gd-anomaly) as a tracer for river water that was diverted into the polder. A clear reduction in the river water contribution was found between very dry conditions on 5 August 2010 and very wet conditions on 22 October. Despite the large river water impact on 5 August, the diverted river water did not propagate up into the small agricultural headwater ditches. Gadolinium proved to be an effective tracer for diverted river water in a polder system. We applied our results to upgrade the interpretation of water quality monitoring data and to validate an integrated nutrient transport model
    Climate Change and the Stability of Water Allocation Agreements
    Ansink, E.J.H. ; Ruijs, A.J.W. - \ 2007
    Milano : Fondazione Eni Enrico Mattei (Note di lavoro della Fondazione Eni Enrico Mattei = Fondazione Eni Enrico Mattei working paper series 16.2007) - 34
    watertoewijzing - waterbeheer - watergebruik - contracten - watervoorziening - rivieren - rivierwater - overeenkomsten - water allocation - water management - water use - contracts - water supply - rivers - river water - agreements
    We analyse agreements on river water allocation between riparian countries. Besides being efficient, water allocation agreements need to be stable in order to be effective in increasing the efficiency of water use. In this paper, we assess the stability of water allocation agreements, using a game theoretic model. We consider the effects of climate change and the choice of a sharing rule on stability. Our results show that both a decrease in mean riverflow and an increase in the variance of riverflow decrease the stability of an agreement. An agreement where the downstream country is allocated a fixed amount of water has the lowest stability compared to other sharing rules.
    Water soluble inorganic trace gases and related aerosol compounds in the tropical boundary layer. An analysis based on real time measurements at a pasture site in the Amazon Basin
    Trebs, I. - \ 2005
    Wageningen University. Promotor(en): J. Slanina. - [S.l.] : S.n. - ISBN 9789085041733 - 144
    rivierwater - aërosolen - gassen - energiebalans - atmosfeer - amazonia - brazilië - grenslaag - river water - aerosols - gases - energy balance - atmosphere - amazonia - brazil - boundary layer

    This dissertation investigates the behavior of water-soluble inorganic trace gases and related aerosol species in the tropical boundary layer. Mixing ratios of ammonia (NH3), nitric acid (HNO3), nitrous acid (HONO), hydrochloric acid (HCl), sulfur dioxide (SO;,) and the corresponding water-soluble aerosol species, ammonium (NH,,1), nitrate (NO3 ), nitrite (NO,), chloride (CI) and sulfate (SO,") were measured at a pasture site in the Amazon Basin (Rondónia, Brazil). Sampling was performed from 12 Sep. to 14 Nov. 2002, covering the late dry (biomass burning) season, the transition period and the onset of the wet season (clean conditions) (LBA-SMOCC*). Measurements were made continuously using a wet-annular denuder (WAD) in combination with a Steam-Jet Aerosol Collector (SJAC) followed by on-line analysis. Real-time data were combined with measurements of the aerosol compounds sodium (Na+), potassium (K), calcium (Ga ), magnesium (Mg2) and low-molecular weight polar organic acids determined using integrated filter samples. Additionally, on-line measured mixing ratios of nitric oxide (NO), nitrogen dioxide (NTX) and ozone (O3) as well as (microj-meteorological quantities are considered, Gaseous NH3 was present in mixing ratios an order of magnitude higher than those of HN0:i, HONO, HCl and SO,. Thermodynamic equilibrium models are used to explore the impact of mineral cations (particularly pyrogenic K+) and LMW polar organic acids on the NH4+-NO3"-C1 -SO.," -H2O aerosol system. Mineral cations present in Amazonian fine mode aerosols significantly balanced aerosol NO.," and SO/ during daytime and (NH4)2SOj appeared to be only a minor aerosol component. Thermodynamic equilibrium permitted the formation of aqueous ??,,??;, and NH^Cl only during nighttime at RH>90 %. During daytime, excess NH3 neutralized LMW polar organic acids, forming aerosol NRy. Local dry and wet deposition rates of inorganic ? are presented. Dry ? deposition was inferred using the "big leaf multiple resistance approach" and a canopy compensation point model. Dry ? deposition is dominated by NH:i and NO3, which featured highest mixing ratios as a consequence of biomass burning activities during the dry season. The pasture site was likely to have a strong potential for daytime NH3 (re-) emission, owing to high canopy compensation points, which are related to high surface temperatures and to direct NH^ emissions from cattle excreta. Total (dry + wet) ? deposition was estimated to be 7.3 - 9.8 kgN ha"1 yr"\ which exceeds predictions for the Amazon region by global chemistry and transport models by at least factor of two.
    Naar een landelijk aquatisch ingreep - effectmodel (vooronderzoek PAW*AQUAREGI) : toetsing van de bruikbaarheid van een aquatische ecotooptypenmethode en een ecologische waterbeoordelingsmethode
    Hoek, W.F. van der; Verdonschot, P.F.M. ; Runhaar, J. ; Gardeniers, J.J.P. ; Peeters, E.T.H.M. - \ 1994
    Wageningen : IBN-DLO (IBN - rapport 117) - 113
    biocenose - biologische technieken - kanalen - nederland - eigenschappen - rivierwater - rivieren - waterlopen - oppervlaktewater - water - waterbeheer - waterkwaliteit - watervoorraden - hydrologie - aquatische ecosystemen - biologische monitoring - biocoenosis - biological techniques - canals - netherlands - properties - river water - rivers - streams - surface water - water - water management - water quality - water resources - hydrology - aquatic ecosystems - biomonitoring
    Hydrologische systeembeschrijving van de Gelderse Poort aan de hand van de waterkwaliteit
    Jansen, P.C. ; Kemmers, R.H. - \ 1994
    Wageningen : DLO-Staring Centrum (Rapport / DLO-Staring Centrum 352) - 55
    kanalen - grondwater - grondwaterstroming - uitspoelen - eigenschappen - rivierwater - rivieren - bodem - waterlopen - oppervlaktewater - water - nederland - gelderland - gelderse poort - canals - groundwater - groundwater flow - leaching - properties - river water - rivers - soil - streams - surface water - water - netherlands - gelderland - gelderse poort
    Verkenning moerasontwikkeling IJsselmeerkust : abiotische kansrijkdom en landbouwperspectief
    Farjon, J.M.J. ; Eck, W. van; Lith, J. van - \ 1994
    Wageningen : DLO-Staring Centrum (Rapport / DLO-Staring Centrum 355) - 50
    plantengemeenschappen - zwampen - wetlands - natuurreservaten - herstel - grondwater - chemische eigenschappen - rivieren - waterlopen - kanalen - water - oppervlaktewater - rivierwater - eigenschappen - landbouwsituatie - economische situatie - natuur - natuurtechniek - ijsselmeer - plant communities - swamps - wetlands - nature reserves - rehabilitation - groundwater - chemical properties - rivers - streams - canals - water - surface water - river water - properties - agricultural situation - economic situation - nature - ecological engineering - lake ijssel
    Life cycle and habitat of Glossiphonia paludosa (Hirudinea: Glossiphonidae), a new leech for The Netherlands.
    Cuppen, J.G.M. - \ 1994
    Netherlands journal of aquatic ecology 28 (1994). - ISSN 1380-8427 - p. 193 - 197.
    rivieren - waterlopen - kanalen - water - rivierwater - hirudinea - hirudo - verspreiding - biologische eigenschappen - diergemeenschappen - rivers - streams - canals - water - river water - hirudinea - hirudo - dispersal - biological properties - animal communities
    Diatomeeengezelschappen in Overijssel
    Maasdam, R. ; Roijackers, R.M.M. ; Cate, J.H. van - \ 1993
    Wageningen etc. : LU [etc.]
    bacillariophyta - biocenose - biologische technieken - kanalen - rivierwater - rivieren - waterlopen - water - waterkwaliteit - nederland - aquatische ecosystemen - biologische eigenschappen - biologisch waterbeheer - biologische monitoring - overijssel - bacillariophyta - biocoenosis - biological techniques - canals - river water - rivers - streams - water - water quality - netherlands - aquatic ecosystems - biological properties - biological water management - biomonitoring - overijssel
    De invloed van atmosferische depositie op diatomeeen en chemische samenstelling van het water in sprengen, beken en bronnen
    Dam, H. van; Mertens, A. ; Janmaat, L.M. - \ 1993
    Wageningen : DLO-IBN (IBN - rapport 052)
    rivieren - waterlopen - kanalen - oppervlaktewater - rivierwater - chemische samenstelling - neerslag - chemische eigenschappen - zuurgraad - zure regen - bacillariophyta - verontreiniging - waterorganismen - nederland - droge depositie - biologische eigenschappen - rivers - streams - canals - surface water - river water - chemical composition - precipitation - chemical properties - acidity - acid rain - bacillariophyta - pollution - aquatic organisms - netherlands - dry deposition - biological properties
    Onderzoek naar de optimalisering van de waterinlaat voor het beheersgebied van het Waterschap De Brielse Dijkring
    Steenvoorden, J.H.A.M. ; Hamaker, P. ; Stuyt, L.C.P.M. - \ 1993
    Wageningen : DLO-Staring Centrum (Rapport / DLO-Staring Centrum 264) - 77
    hydrologie - rivierwater - zoutgehalte - kwel - waterlopen - waterbeheer - wateraanvoer - zuid-holland - glastuinbouw - zuidhollandse eilanden - hydrology - river water - salinity - seepage - streams - water management - water advance - zuid-holland - greenhouse horticulture - zuidhollandse eilanden
    Aanzet tot een ecologische indeling van oppervlaktewateren in Nederland
    Verdonschot, P.F.M. ; Runhaar, J. ; Hoek, W.F. van der - \ 1992
    Leersum : IBN-DLO [etc.] (RIN - rapport 92/1) - 174
    hydrobiologie - biocenose - rivieren - waterlopen - kanalen - water - rivierwater - nederland - aquatische ecosystemen - biologische eigenschappen - hydrobiology - biocoenosis - rivers - streams - canals - water - river water - netherlands - aquatic ecosystems - biological properties
    Ecological characterization of surface waters in the province of Overijssel, The Netherlands
    Verdonschot, P.F.M. - \ 1990
    Agricultural University. Promotor(en): C.W. Stortenbeker; W.J. Wolff. - S.l. : Verdonschot - 255
    ecologie - hydrologie - hydrobiologie - biocenose - biologische technieken - waterkwaliteit - rivieren - waterlopen - kanalen - water - rivierwater - meren - reservoirs - plassen - zoet water - nederland - ecohydrologie - aquatische ecosystemen - biologische monitoring - biologische eigenschappen - binnenwateren - overijssel - ecology - hydrology - hydrobiology - biocoenosis - biological techniques - water quality - rivers - streams - canals - water - river water - lakes - reservoirs - ponds - fresh water - netherlands - ecohydrology - aquatic ecosystems - biomonitoring - biological properties - inland waters - overijssel

    Nowadays many surface waters in The Netherlands tend to become ecologically uniform with the same mediocre quality. A differentiated approach to water management is necessary to stop this process of impoverishment of aquatic ecosystems. In The Netherlands the provincial authorities represent the appropriate level at which this differentiated approach to water management can be put into practice. Such an approach has been realized by the Department of Water Management of the Province of Overijssel. As a part of this approach the project 'Ecological characterization of surface waters in the province of Overijssel (EKOO)' was formulated in 1981.

    The aims of the EKOO-project are to develop a regional ecological characterization of surface waters based on macrofauna composition and to reach a better understanding of the variety and the structure of the macrofauna communities present in the waters of the province of Overijssel. The project thus provides knowledge of aquatic ecosystems on a regional scale and a basis for the development of water management policies. An additional aim of this study is to develop the typological approach used in water management.

    The typological approach used can be interpreted as an integration of the zonal concept and the continuum concept. Taxon combinations will be described as types. Within a limited range of environmental conditions, these types are representative of communities, but at the same time they together form a continuum. Due to hierarchical relations between major environmental variables (master factors) and evolutionary and historical factors, a type can only be described within a biogeographical region.

    The study was designed as a qualitative survey but organized as much as possible along quantitative lines. Macrofauna composition (taxon composition and abundance) was chosen as a basic parameter. About 70 variables that were considered physically, chemically or biologically relevant, were measured at each sampling site. In total 664 sites were sampled, distributed over about twenty physico- geographical water types. These twenty types include all the major environmental variables relevant to this region; they overlap in abiotic features. The physico-geographical water typology was used as a practical tool for carrying out the survey, but was not used in obtaining the ecological typology. The ecological typology was derived from the collected biotic and abiotic data alone.

    A study on the reproducibility of the standard macrofauna sample was carried out. The standard pond net macrofauna sampling technique used in The Netherlands appears to present only a semi-quantitative picture of the more common taxa. With this technique only about 55% of all the taxa present at a site at the moment of sampling were collected. However, when the standard pond net was used for a regional typological study it appeared that seasonal differences as well as inconsistencies due to sample technique were of little significance compared with differences between types. It was concluded that the reproducibility of a macrofauna sample is sufficient for typological purposes.

    For data analysis, the twenty physico-geographical water types were combined into five main categories. The abiotic and biotic data were processed for these five main categories. Later, all the data were processed together to obtain an ecological water typology for the province of Overijssel. Multivariate analysis techniques are appropriate in data analysis for typologi~-al purposes. Different multivariate analysis techniques (cluster analysis and canonical ordination) were used to derive and describe site groups in terms of taxon composition and mean environmental conditions. Sites intermediate between groups were manually relocated by using information from other sources (e.g. literature) about the ecology of the constituent taxa. The resulting site groups were termed cenotypes.

    Six cenotypes were distinguished among helocrene springs. The main differences between the cenotypes were related to hydrology (mainly duration of drought) and acidity. Furthermore, the nutrient content and/or the load of organic material differed between related cenotypes. Each cenotype contained its own microhabitat group(s). The microhabitat groups, except for two, were associated with the duration of the drought period. The other two groups were associated with the spring source and the spring stream, respectively. The natural reference situation for helocrene springs probably resembles some of the actual helocrene springs investigated. The most important human activities causing disturbance are those which cause changes in the chemical composition of the groundwater. The management of springs should be directed at this factor.

    Eleven cenotypes were distinguished among the streams. The main differences between the cenotypes were related to dimensions, "stream-character", duration of drought and the load of organic material. All the streams were more or less influenced by human activities. Stream regulation, especially, has caused a dramatic change in the taxon composition. Only about 2% of the total length of streams is still more or less natural in 'stream-character' and its corresponding community. These 2% are only preserved because of their geographical position on the steepest slopes. In general, efforts at improvement of the ecological character should be directed at the physical and hydraulic conditions.

    Eleven cenotypes were distinguished among the ditches. The main differences between the cenotypes were related to dimensions, duration of drought, acidity and current. Furthermore, the nutrient content and/or load of organic material differed between related cenotypes . It is illustrated that the taxon combination found in a ditch reflects a stage of succession in space (profile structure) and time (maturity). Therefore, an overlap in taxon combination between cenotypes occurred (continuum). Ditches are artificial ecosystems which mainly occur in cultivated areas (which implies eutrophication) and depend on regular human interference (cleaning, dredging). The ecological management of ditches should be based upon the relationbetween profile structure, succession stage and human interference.

    Eleven cenotypes were distinguished among the rivers, canals and large lakes. They showed great overlap in taxa (mostly opportunists) and in environmental circumstances. Increasing dimensions of the line-shaped more or less running waters go together with an increasing drainage area. These large-sized water bodies function as collectors of nutrients, organic material and toxicants. This results in chronic stress and probably the disappearance of most taxa occurring originally. The chronic stress also overrules the natural master factors of current and dimensions. Only a few taxa are still characteristic for the reach of a river or the gradient in size of canals.

    Nine cenotypes were distinguished among the ponds and small lakes. The main differences between the cenotypes were related to duration of drought, acidity, morphology and nutrient load. In particular, the four cenotypes within the group of stagnant, pH-neutral ponds/lakes showed an overlap in taxon compostion. These cenotypes represent a web-shaped continuum dominated by dimensions (relation of width to depth), nutrient load, and bottom composition (especially mesotrophic peat). The most important processess induced by men are acidification, eutrophication, and changes in the original hydrology.

    Cenotypes of different main physico-geographical watertypes can be very similar. Therefore they should be combined or rearranged. This is done by processing all abiotic and biotic data together. Again, cluster analysis and canonical ordination were applied. After each ordination along two axes, the distinctive cenotypes were removed and the remaining sites were reordinated. Through this progressive removal of groups of sites, finally, 42 cenotypes were distinguished. Some notes on the ecology of the typifying taxa and the most important environmental variables were made for each cenotype.

    The mutual relations between the cenotypes are shown in a hierarchical dendrogram based on biological similarity as well as in a web of cenotypes (Figure 11.1).

    The hierarchical dendrogram shows, among others, that a group of cenotypes related to middle and lower reaches of regulated streams, small rivers, ditches and some of the medium-sized, more or less stagnant waters, - all hypertrophic, mesosaprobic environments -, has a fair number of the macrofauna in common. Apparantly, human activity (e.g. by regulation of streams, discharge of wastes and agricultural activity in the watershed) leads to a decreasing role of the factor current in running waters and the factors dimensions (in fact shape and depth) and bottom type in the stagnant waters and leads to an impoverishment of the macrofauna.

    The web of cenotypes illustrates the mutual position of the cenotypes, the transitions between the cenotypes (the continuum) and the major environmental gradients. The four most dominant factors are 'stream-character', acidity, duration of drought, and dimensions.

    To evaluate a given water body, even subjectively, it is necessary to compare it with other water bodies in different states. This scale of evaluation needs a reference water. The reference water is not necessarily an endpoint of succession nor a pristine situation, but it should at least represent a situation that can be used to indicate the desired direction of improvement. In choosing the reference communities for water management one must focus on communities present in waters where major environmental conditions are less disturbed. Such waters are the undisturbed streams, the oligotrophic moorland pools, and the mesotrophic old meanders cut off from streams.

    The regional ecological typology presented (Figure 11.1) offers a tool for establishing the developmental direction from a community observed in the field towards the reference community. It is also a tool to determine the reference community for a particular water body. Because the factors in the web of cenotypes are a result of a descriptive study, the web cannot be used without caution as a predictive tool; the factors are purely indicative. The typology and associated ecological concepts are a tool to help solving water management problems. It is a basis, among others, for monitoring and assessment of waterquality, it indicates potential capacities Of surface waters and it provides guidelines for management and restoration of surface waters. May it be serve to the advantage of the environment around us.

    Waterkwaliteitsonderzoek op de Yerseke Bank, in de geul bij het buitendijkse bedrijfsterrein "Korringaweg" te Yerseke, op de Oosterschelde en op het Grevelingenmeer : resultaten periode augustus 1987 - december 1988
    Kesteloo - Hendrikse, J.J. - \ 1989
    IJmuiden : RIVO (Rapport / Rijksinstituut voor Visserijonderzoek AQ 89-02) - 31
    kanalen - hydrologie - instrumenten (meters) - meting - monitoring - nederland - eigenschappen - rivierwater - rivieren - statistiek - waterlopen - oppervlaktewater - water - waterverontreiniging - waterkwaliteit - oosterschelde - grevelingen - canals - hydrology - instruments - measurement - monitoring - netherlands - properties - river water - rivers - statistics - streams - surface water - water - water pollution - water quality - eastern scheldt - grevelingen
    The soil environment of the intertidal area in the Westerschelde Netherlands Belgium
    Oenema, O. ; Steneker, R. ; Reynders, J. - \ 1988
    Hydrobiological Bulletin 22 (1988)1. - ISSN 0165-1404 - p. 21 - 30..
    kanalen - delta's - estuaria - zoet water - geologie - zware metalen - vermenging - morfologie - nederland - rivierwater - rivieren - zout water - waterlopen - oppervlaktewater - waterverontreiniging - waterkwaliteit - biologische eigenschappen - westerschelde - zeeland - waterbodems - canals - deltas - estuaries - fresh water - geology - heavy metals - mixing - morphology - netherlands - river water - rivers - saline water - streams - surface water - water pollution - water quality - biological properties - western scheldt - zeeland - water bottoms
    hydrodynamic forces and sediment discharges determine the sedimentary environment and surface morphology of the intertidal area in the Westerschelde estuary in the S.W. Netherlands. Sandflats (clay, content < 8%) are found in the central part, mudfla
    Hydrobiologisch onderzoek in de Maas; een aanzet tot biologische monitoring van grote rivieren.
    Smit, H. ; Gardeniers, J.J.P. - \ 1986
    H2O : tijdschrift voor watervoorziening en afvalwaterbehandeling 19 (1986). - ISSN 0166-8439 - p. 314 - 317.
    biologische technieken - kanalen - rivierwater - rivieren - waterlopen - water - waterkwaliteit - biologische eigenschappen - biologische monitoring - maas - biological techniques - canals - river water - rivers - streams - water - water quality - biological properties - biomonitoring - river meuse
    Westland versus Rijnzout
    Smits, R. ; Heijman, W.J.M. - \ 1985
    Landbouwkundig Tijdschrift 97 (1985)9. - ISSN 0927-6955 - p. 29 - 32.
    oogstschade - irrigatiewater - rivierwater - zout water - natriumchloride - bodemverontreiniging - bodemzoutgehalte - bodemgiftigheid - waterkwaliteit - oogstverliezen - rijn - zuid-holland - glastuinbouw - westland - crop damage - irrigation water - river water - saline water - sodium chloride - soil pollution - soil salinity - soil toxicity - water quality - yield losses - river rhine - greenhouse horticulture
    In dit artikel wordt voor het jaar 1983 een schatting gemaakt van de, door verzilting veroorzaakte, opbrengstverliezen voor de tuinbouw en wordt de daaruit voortvloeiende schade voor de gehele Nederlandse economie globaal berekend
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