Staff Publications

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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    MIPWA 2.2 : vervangen van CAPSIM door MetaSWAP
    Hoogewoud, J.C. ; Veldhuizen, A.A. ; Hunink, J.C. ; Walsum, P.E.V. van - \ 2015
    Deltares - 98
    bodemwater - hydrologie - bodemwaterbeweging - grondwaterstand - modellen - soil water - hydrology - soil water movement - groundwater level - models
    MIPWA 2.1 gebruikt het onverzadigde zone model CAPSIM van Alterra. Dit model wordt niet meer ondersteund. De opvolger is het model MetaSWAP. Dit model geeft een betere conceptuele beschrijving van de onverzadigde zone, een deel van de uitvoer is makkelijk te bekijken in iMOD en geïnterpoleerde meteorologische data van het KNMI is reeds geschikt als invoer. De MIPWA groep heeft Deltares en Alterra gevraagd CAPSIM te vervangen door MetaSWAP. Het bleek dat het schijnspiegel concept in CAPSIM (onverwacht) niet zonder meer overgenomen kon worden in MetaSWAP
    Experiments on the movement of pesticides in sandy soils to groundwater : prospects of testing preferential transport models
    Leistra, M. ; Boesten, J.J.T.I. - \ 2012
    Wageningen : Alterra, Wageningen-UR (Alterra-rapport 2291) - 60
    zandgronden - hydraulisch geleidingsvermogen - pesticiden - bodemwaterbeweging - waterverontreiniging - experimenteel veldonderzoek - sandy soils - hydraulic conductivity - pesticides - soil water movement - water pollution - field experimentation
    Many agricultural areas with humic-sandy and loamy-sandy soils are used also for the extraction of water for drinking-water supply. Model concepts have been developed for the fast preferential transport of plant protection products (pesticides) in such soils, e.g. by fingered and funneled flow. An inventory is given of experiments that may be suitable for the testing of preferential transport models for cultivated sandy soils (without macropores). The pesticide concentrations per depth in soil are highly variable, due to local differences in transport, adsorption and transformation. Measurements in both the subsoil and in the upper groundwater are scarce, also due to sampling problems. Suggestions are given to improve the characterisation of soil profiles and weather conditions. Sampling methods for soil and soil solution can easily miss the preferential transport pathways. The methods of pesticide analysis in soils samples are often not sensitive enough to measure concentrations relevant for groundwater quality. The present study serves as the starting point for selecting the most suitable data sets for model testing and for the design of more complete and detailed data sets in the future.
    3D-modellering van nutriëntentransport door bodem en grondwater
    Janssen, G. ; Griffioen, J. ; Grift, B. van der; Groenendijk, P. - \ 2011
    H2O : tijdschrift voor watervoorziening en afvalwaterbehandeling 44 (2011)6. - ISSN 0166-8439 - p. 27 - 29.
    nutriëntenstromen - bodem - grondwater - transportprocessen - bodemwaterbeweging - nutriëntenuitspoeling - waterkwaliteit - modellen - nutrient flows - soil - groundwater - transport processes - soil water movement - nutrient leaching - water quality - models
    Deltares heeft samen met Alterra een concept ontwikkeld voor driedimensionale modellering van nutriëntentransport. Door ANIMO te koppelen aan RT3D wordt de kennis over nutriëntenprocessen in de bodem gekoppeld aan transportprocessen in het diepere grondwater. Hiermee kan men de bijdrage van de uitspoeling uit de bodem aan de oppervlaktewaterkwaliteit, de afhankelijkheden tussen gebieden en de mate van bedreiging van bijvoorbeeld grondwaterlichamen en drinkwaterwinningen beter inschatten en voorspellen. Tegelijkertijd wordt een voorzet gegeven voor de invulling van een onderdeel van de kwaliteitsmodellering in het hydrologische modelspoor van het Nationaal Hydrologisch Instrumentarium.
    MetaSWAP_V7_2_0. Rapportage van activiteiten ten behoeve van certificering met Status A
    Walsum, P.E.V. van; Veldhuizen, A.A. - \ 2011
    Wageningen : WUR (WOt-werkdocument 276) - 116
    bodemfysica - transportprocessen - bodemwaterbeweging - hydrologie - oppervlaktewater - waterbalans - plant-water relaties - atmosfeer - simulatiemodellen - soil physics - transport processes - soil water movement - hydrology - surface water - water balance - plant water relations - atmosphere - simulation models
    Veel vragen over het waterbeheer betreffen situaties en processen die worden beïnvloed door hydrologische terugkoppelingen op regionale en zelfs nationale schaal. MetaSWAP is bedoeld voor het vervangen van SWAP bij het grootschalig doorrekenen van bodem-plant-atmosfeerkolommen die gekoppeld zijn aan geïntegreerde gebiedsmodellen van grond- en oppervlaktewater. MetaSWAP is een ‘meta’-model van SWAP. Het metaconcept is gebaseerd op een vereenvoudigde oplossing van de niet-lineaire partiële differentiaalvergelijking om bodemfysische processen te beschrijven, de zogenaamde Richards-vergelijking. Deze vergelijking wordt vervangen door twee ‘gewone’ differentiaalvergelijkingen, één voor de procesbeschrijving, en één voor de waterbalans. Om het informatieverlies dat bij die vereenvoudiging optreedt te compenseren, is het nodig om MetaSWAP te kalibreren en te valideren op SWAP. Dit document beschrijft hoe dat gedaan wordt, en tevens hoe de kwaliteit van het model is geborgd volgens de zogenaamde ‘Status A’ standaard van de WOT Natuur & Milieu.
    Swap version 3.2 : theory description and user manual
    Kroes, J.G. ; Dam, J.C. van; Groenendijk, P. ; Hendriks, R.F.A. ; Jacobs, C.M.J. - \ 2008
    Wageningen : Alterra (Alterra rapport 1649) - 262
    bodemwater - simulatiemodellen - bodemwaterbeweging - waterstroming - transportprocessen - evaporatie - verzilting - numerieke methoden - agrohydrologie - soil water - simulation models - soil water movement - water flow - transport processes - evaporation - salinization - numerical methods - agrohydrology
    SWAP 3.2 simulates transport of water, solutes and heat in the vadose zone. It describes a domain from the top of canopy into the groundwater which may be in interaction with a surface water system. The program has been developed by Alterra and Wageningen University, and is designed to simulate transport processes at field scale and during whole growing seasons. This is a new release with special emphasis on numerical stability, macro pore flow, and options for detailed meteorological input and linkage to other models. This manual describes the theoretical background, model use, input requirements and output tables
    Hydrologie op basis van karteerbare kenmerken
    Gaast, J.W.J. van der; Massop, H.T.L. ; Vroon, H.R.J. ; Staritsky, I.G. - \ 2007
    H2O : tijdschrift voor watervoorziening en afvalwaterbehandeling 40 (2007)19. - ISSN 0166-8439 - p. 65 - 68.
    hydrologie - grondwaterstand - simulatiemodellen - kalibratie - karteringen - toepassingen - klimaatverandering - bodemwaterbeweging - stroomgebieden - nederland - onderzoeksprojecten - hydrology - groundwater level - simulation models - calibration - surveys - applications - climatic change - soil water movement - watersheds - netherlands - research projects
    Onderzoek van de Commissie Waterbeheer 21e Eeuw (WB21) heeft o.a. geresulteerd in een wateropgave. In dit onderzoek is een methode ontwikkeld waarmee inzicht kan worden verkregen in de hydrologische variabelen van gebieden in Nederland. De methode kan een basis vormen voor het in beeld krijgen van de effecten van waterhuishoudkundige maatregelen en daarmee aangeven in hoeverre kan worden voldaan aan de wateropgave. In eerste instantie is een landsdekkende ruimtelijke schematisatie uitgevoerd en is de Gt-kaart 1 : 50 000 geactualiseerd. Vervolgens zijn SWAP-modellen voor een groot aantal mogelijke situaties geparametriseerd en gekalibreerd. Middels metamodellen, welke van de modelresultaten zijn afgeleid, kunnen verschillende hydrologische variabelen in kaart worden gebracht. Het kan hierbij bijvoorbeeld gaan om kwel, afvoer, berging in zowel grondwater als oppervlaktewater of fluxen. Validatie van enkele variabelen geeft aan dat de gegenereerde kaarten plausibel zijn
    Beschrijving module OSmanSoil : een eenvoudig bodemmodel voor de beschrijving van waterbeweging, convectief stikstoftransport, water- en stikstofopname, denitrificatie, nitrificatie en mineralisatie
    Heinen, M. - \ 2005
    Wageningen : Alterra (Alterra-rapport 1261)
    bodem - modellen - transportprocessen - beweging in de bodem - bodemwaterbeweging - stikstof - denitrificatie - nitrificatie - bodemtemperatuur - soil - models - transport processes - movement in soil - soil water movement - nitrogen - denitrification - nitrification - soil temperature
    In het onderzoek naar organisch stofmanagement in biologische kasteelt (bijvoorbeeld Marcelis et al., 2003) is tot nu toe gebruik gemaakt van een gekoppeld bodem-plant model, bestaande uit FUSSIM2 (Heinen and de Willigen, 1998; 2001) en INTKAM (Gijzen, 1994). Omdat de rekentijd van dit gekoppelde model relatief groot is, kon dit niet worden toegepast in het te ontwikkelen adviesmodel voor organische bemesting. Daarom is besloten om een eenvoudig bodemmodel op te zetten, welke ongekoppeld met het plantmodel kan functioneren. In dit rapport wordt kort de theorie en gebruikershandleiding van het eenvoudige bodemmodel beschreven
    Simulation of pesticide leaching in a cracking clay soil with the PEARL model
    Scorza, R.P. ; Boesten, J.J.T.I. - \ 2005
    Pest Management Science 61 (2005)5. - ISSN 1526-498X - p. 432 - 448.
    uitspoelen - grondwaterverontreiniging - pesticiden - modellen - zware kleigronden - bentazon - imidacloprid - bodemwaterbeweging - leaching - groundwater pollution - pesticides - models - clay soils - bentazone - imidacloprid - soil water movement - spatial variability - solute transport - sandy soil - field - persistence - water - translocation - validation - herbicide - bentazon
    Testing of pesticide leaching models is important to increase confidence in their use in pesticide registration procedures world-wide. The chromatographic PEARL model was tested against the results of a field leaching study on a cracking clay soil with a tracer (bromide), a mobile pesticide (bentazone) and a moderately sorbing, persistent pesticide (imidacloprid). Input parameters for water flow and solute transport were obtained from site-specific measurements and from literature. The model was tested using a stepwise approach in which each sub-model was sequentially and separately tested. Uncalibrated simulations for the water flow resulted in moisture profiles that were too wet. Calibration of the hydraulic relationships resulted in a good description of the moisture profiles. Calibration of the dispersion length was necessary to obtain a good description of bromide leaching. The calibrated dispersion length was 61 cm, which is very long and indicates a large non-uniformity of solute transport. The half-life of bentazone had to be calibrated to obtain a good description of its field persistence. The calibrated half-life was 2.5 times shorter than the half-life derived from the laboratory studies. Concentrations of bentazone in drain water and groundwater were described reasonably well by PEARL. Although measured and simulated persistence of imidacloprid in soil corresponded well, the bulk of the imidacloprid movement was overestimated by PEARL. However, imidacloprid concentrations in drain water were underestimated. In spite of the extensive calibration of water flow and tracer movement, the behaviour of the moderately sorbing pesticide imidacloprid could not be simulated. This indicates that the convection-dispersion equation cannot be used for accurate simulation of pesticide transport in cracking clay soils (even if extremely long dispersion length is used). Comparison of the model results from a poorly sorbed chemical (bentazone) and a moderately sorbed chemical (imidacloprid) were useful in defining the limitations of using a chromatographic flow model to simulate the effects of preferential flow.
    Assessing uncertainty propagation through physically based models of soil water flow and solute transport
    Brown, J. ; Heuvelink, G.B.M. - \ 2005
    In: Encyclopedia of hydrological sciences / Anderson, M.G., Chichester (UK) [etc.] : Wiley - ISBN 9780471491033 - p. 1181 - 1195.
    bodemwaterbeweging - modellen - soil water movement - models
    Soil hydrological models are inherently imperfect because they abstract and simplify ¿real¿ hydrological patterns and processes. Indeed, an important aim of modeling is to establish the simplest description possible for adequately addressing a particular problem. Also, models are frequently based on input data that are known to be inadequate for some practical purpose. Thus, uncertainties in model outputs originate from uncertainties in input data, which include measurement and interpolation errors, and in models that include conceptual, logical, mathematical, and computational errors. Understanding the causes and consequences of uncertainty in soil hydrological modeling is useful for: (i) establishing the utility of data and models as decision-support tools; (ii) directing resources towards improving data and models, and (iii) seeking alternative ways of managing soils when the opportunities for accurate modeling are limited. This chapter focuses on statistical methods for assessing uncertainty in soil data and models, propagating uncertainties through models, and assessing the contribution of different sources of uncertainty to the overall uncertainties in model predictions. In addition, it explores the impacts of scale, and changes between scales, on the outcomes of an uncertainty analysis. It concentrates on physically based models of soil water flow and solute transport, and provides numerous examples from the literature here
    Uitspoelingsgevoelige gronden op de kaart; werkwijze en resultaten
    Kekem, A.J. van; Hoogland, T. ; Horst, J.B.F. van der - \ 2005
    Wageningen : Alterra (Alterra-rapport 1080) - 89
    bodemwater - grondwaterstand - uitspoelen - nitraten - cartografie - bodemeigenschappen - hydrodynamica - bodemwaterbeweging - veengronden - dierlijke meststoffen - overheidsbeleid - nederland - bodemkarteringen - kaarten - geostatistiek - soil water - groundwater level - leaching - nitrates - mapping - soil properties - hydrodynamics - soil water movement - peat soils - animal manures - government policy - netherlands - soil surveys - maps - geostatistics
    Voor de uitvoering van het mestbeleid in Nederland is het van belang om de uitspoelingsgevoeligheid voor nitraat van de bodems in Nederland zo goed mogelijk te kennen. Deze uitspoelingsgevoeligheid hangt o.a. af van de grondsoort en de grondwaterstand om hiervan een inschatting te maken dienen basisbestanden van de bodem en de grondwaterstanden voldoende nauwkeurig en actueel dienen te zijn. Uit een quick scan bleek dat 47% van de oppervlakte veengronden in Oost-Nederland is gedeformeerd naar een ander bodemtype, met name zandgronden. Voor de zand- en lössgronden van Nederland is met een geostatistische methode de grondwaterdynamiek geactualiseerd en er is een methodiek ontwikkeld om op basis hiervan de landbouwpercelen op zand- en lössgronden te classificeren naar uitspoelingsgevoeligheid. Deze berekeningen zijn uitgevoerd voor verschillende scenario's waarin is gevarieerd met de GHG grens, de areaal fractie per perceel en een kanscriterium. In het gewijzigd beleid is ervoor gekozen om niet op perceelsniveau uitspoelingsgevoelige gronden aan te wijzen. Daarom is het areaal uitspoelingsgevoelige grond ook voor pixels van 25x25 meter berekend. Voor de zandgronden bedraagt het areaal uitspoelingsgevoelige gronden met een GHG ≥ 70 cm en een GLG ≥ 120, ongeveer 335000 ha, 36% van het landbouw areaal op zandgronden
    Kwel en Waternood; ontwikkeling van een methode voor kartering van kwel en de evaluatie van de gevolgen van peilbeheer voor kwelpatronen
    Kemmers, R.H. ; Delft, S.P.J. van; Gaast, J.W.J. van der - \ 2005
    Wageningen : Alterra (Alterra-rapport 1034) - 75
    waterkwaliteit - kwel - hydrologie - grondwaterspiegel - bodemwaterbeweging - cartografie - natuurbescherming - waterstand - noord-brabant - peilbeheer - water quality - seepage - hydrology - water table - soil water movement - mapping - nature conservation - water level - noord-brabant - water level management
    In aanvulling op de waternoodmethodiek is onderzocht of een veldinventarisatiemethode voor de waterkwaliteit ontwikkeld kon worden waarmee ruimtelijke kaartbeelden van ecologisch relevante kwel tot in het maaiveld kunnen worden gegenereerd. Als hulpinformatie om puntgegevens over de waterkwaliteit te extrapoleren naar ruimtelijke patronen maakt de methodiek gebruik van gebiedsdekkende kwelfluxen die door het hydrologische model SWAP worden berekend. In de ontwikkelde methodiek is daardoor een koppeling aanwezig tussen peilbeheer en kwelkwaliteit. Geconcludeerd wordt dat voorspelling van het watertype aan de hand van eenvoudige veldinformatie nog niet geheel bevredigend is in gebieden waar overwegend agrarisch grondgebruik plaatsvindt. De met het model berekende kwelfluxen worden nog overschat, door een onbevredigende modelformulering van drainage. De ruimtelijke extrapolatie van de voorspelde grondwaterverwantschap met gebiedsdekkende hulpinformatie over kwelfluxen levert een beeld op dat op hoofdlijnen voldoet aan de verwachting, maar nog voor verbetering vatbaar is
    Kwel in beeld : Inventarisatie van kwelkwaliteit ten behoeve van natuurgerichte landevaluatiesysteem NATLES
    Jansen, P.C. - \ 2004
    Wageningen : Alterra (Alterra-rapport 904) - 56
    kwel - bodemwaterbeweging - inventarisaties - landevaluatie - cartografie - natuurbescherming - utrechtse heuvelrug - seepage - soil water movement - inventories - land evaluation - mapping - nature conservation - utrechtse heuvelrug
    De zuurkaart die het model NATLES als één van de basiskaarten voor natuurevaluatie gebruikt wordt samengesteld op basis van onder andere de hardheid van het grondwater. De hardheid is in maximaal 3 klassen onderscheiden: hard, matig hard en zacht grondwater. De volgende stap in de ontwikkeling van NATLES is gericht op een uitbreiding met een extra, matig zacht, watertype. Niet allen het model zelf, maar ook op de verspreidingskaart waarop de watertypen staan aangegeven moet hiervoor worden aangepast. In een proefgebied aan de zuidflank van de Utrechtse Heuvelrug is een methode ontwikkeld om de verspreiding van (kwel)watertypen in kaart te brengen. Met de hieruit afgeleide kweltypenkaart zijn met NATLES voor 2 hydrologische scenario’s de gevolgen voor zuurgraad berekend.
    Three-phase flow analysis of dense nonaqueous phase liquid infiltration in horizontally layered porous media
    Wipfler, E.L. ; Dijke, M.I.J. van; Zee, S.E.A.T.M. van der - \ 2004
    Water Resources Research 40 (2004). - ISSN 0043-1397 - p. W10101 - W10101.
    infiltratie - grondwater - waterkwaliteit - hydrologie - poreus medium - grondwaterstroming - bodemwaterbeweging - infiltration - groundwater - water quality - hydrology - porous media - groundwater flow - soil water movement - capillary forces - redistribution
    We considered dense nonaqueous phase liquid (DNAPL) infiltration into a water-unsaturated porous medium that consists of two horizontal layers, of which the top layer has a lower intrinsic permeability than the bottom layer. DNAPL is the intermediate-wetting fluid with respect to the wetting water and the nonwetting air. The layer interface forms a barrier to DNAPL flow, which causes the DNAPL to spread out horizontally just above the interface. An analytical approximation has been developed to estimate the DNAPL pressure and saturation and the horizontal extension of the DNAPL above the layer interface at steady state for low water saturations. The analytical approximation shows that the DNAPL infiltration is determined by five dimensionless numbers: the heterogeneity factor ¿, the capillary pressure parameter ¿, the gravity number N g , the ratio of the capillary and gravity numbers N c /N g , and the critical DNAPL pressure P o c . Its predictions were compared with the results of a numerical three-phase flow simulator for a number of parameter combinations. For most of these combinations the analytical approximation predicts the DNAPL pressure and saturation profiles at the interface adequately. Using the analytical approximation, we carried out a sensitivity study with respect to the maximum horizontal extension of the plume. The extension of the plumes appears to be highly sensitive to variation of the dimensionless numbers P o c , ¿ and ¿
    On the use of unsaturated flow and transport models in nutrient and pesticide management
    Vanclooster, M. ; Boesten, J.J.T.I. ; Tiktak, A. ; Jarvis, N. ; Kroes, J.G. ; Muñoz-Carpena, R. ; Clothier, B.E. ; Green, S.R. - \ 2004
    In: Unsaturated-zone modeling: progress, challenges and applications. - Dordrecht [etc.] : Kluwer (Wageningen UR Frontis Series 6) - ISBN 9781402029189 - p. 331 - 361.
    bodemwaterbeweging - infiltratie - voedingsstoffen - pesticiden - waterverontreiniging - modellen - soil water movement - infiltration - nutrients - pesticides - water pollution - models
    In this paper, we show how flow and transport models are introduced in the nutrient and pesticide management decision-making process. Examples are given of the use of flow and transport models in (i) field-scale nutrient and pesticide management; (ii) the identification and evaluation of fertilization and pesticide application practices supporting the implementation of regional-scale environmental management plans; and (iii) the registration of plant-protection products
    Reality and fiction of models and data in soil hydrology
    Pachepsky, Y.A. ; Smettem, K.R.J. ; Vanderborght, J. ; Herbst, M. ; Vereecken, H. ; Wösten, J.H.M. - \ 2004
    In: Unsaturated-zone modeling: progress, challenges and applications. - Dordrecht [etc.] : Kluwer (Wageningen UR Frontis Series 6) - ISBN 9781402029189 - p. 231 - 260.
    bodemwaterbeweging - hydraulisch geleidingsvermogen - remote sensing - modellen - soil water movement - hydraulic conductivity - remote sensing - models
    The objective of this paper is to contribute to the ongoing discussion on strengths, weaknesses, opportunities and trends of existing modeling approaches in soil hydrology. We present a comprehensive case study of using integrated data to build a model of groundwater pollution for a watershed, and use this case study to illustrate current opportunities and problems related to quantifying soil variability with remote sensing, geophysical methods and topographic information
    Energy and water flow through the soil - vegetation - atmosphere system: the fiction of measurements and the reality of models
    Menenti, M. ; Jia, L. ; Bastiaanssen, W.G.M. - \ 2004
    In: Unsaturated-zone modeling; Progress, challenges and applications / Feddes, R.A., de Rooij, G.H., van Dam, J.C., - p. 211 - 229.
    bodemwaterbeweging - plant-water relaties - energiebalans - evaporatie - modellen - soil water movement - plant water relations - energy balance - evaporation - models
    This paper summarizes basic concepts and definitions in models of the SVA system and then emphasizes inconsistencies between model variables and observations for the soil, vegetation and atmosphere elements. This is done first in a qualitative sense, then analytically for the observations of the radiometric temperature of vegetation canopies
    Concepts and dimensionality in modeling unsaturated water flow and solute transport
    Dam, J.C. van; Rooij, G.H. de; Heinen, M. ; Stagnitti, F. - \ 2004
    In: Unsaturated-zone modeling; progress, challenges and applications / Feddes, R.A., de Rooij, G.H., van Dam, J.C., Dordrecht etc. : Kluwer (Wageningen UR Frontis Series 6) - ISBN 9781402029189 - p. 1 - 36.
    bodemwaterbeweging - bodemwater - infiltratie - modellen - soil water movement - soil water - infiltration - models
    Many environmental studies require accurate simulation of waterand solute fluxes in the unsaturated zone. This paper evaluatesone- and multi-dimensional approaches for soil water flow as wellas different spreading mechanisms to model solute behavior atdifferent scales. For quantification of soil water fluxes,Richards equation has become the standard. Although currentnumerical codes show perfect water balances, the calculated soilwater fluxes in case of head boundary conditions may dependlargely on the method used for spatial averaging of the hydraulicconductivity. Atmospheric boundary conditions, especially in thecase of phreatic groundwater levels fluctuating above and below asoil surface, require sophisticated solutions to ensureconvergence. Concepts for flow in soils with macropores andunstable wetting fronts are still in development. One-dimensionalflow models are formulated to work with lumped parameters inorder to account for the soil heterogeneity and preferentialflow. They can be used at temporal and spatial scales that are ofinterest to water managers and policymakers. Multi-dimensionalflow models are hampered by data and computation requirements.Their main strength is detailed analysis of typicalmulti-dimensional flow problems, including soil heterogeneity andpreferential flow. Three physically based solute-transportconcepts have been proposed to describe solute spreading duringunsaturated flow: The stochastic-convective model (SCM), theconvection-dispersion equation (CDE), and the fractionaladvection-dispersion equation (FADE). A less physical concept isthe continuous-time random-walk process (CTRW). Of these, the SCMand the CDE are well established, and their strengths andweaknesses are identified. The FADE and the CTRW are more recent,and only a tentative strength weakness opportunity threat (SWOT)analysis can be presented at this time. We discuss the effect ofthe number of dimensions in a numerical model and the spacingbetween model nodes on solute spreading and the values of thesolute-spreading parameters. In order to meet the increasingcomplexity of environmental problems, two approaches of modelcombination are used: Model integration and model coupling. Amain drawback of model integration is the complexity of theresulting code. Model coupling requires a systematic physicaldomain and model communication analysis. The setup andmaintenance of a hydrologic framework for model coupling requiressubstantial resources, but on the other hand, contributions canbe made by many research groups.
    Unsaturated-zone modeling; Progress, challenges and applications
    Feddes, R.A. ; Rooij, G.H. de; Dam, J.C. van - \ 2004
    Dordrecht : Kluwer Academic Publishers (Wageningen UR Frontis series vol. 6) - ISBN 9781402029189 - 364
    bodemwaterbeweging - bodemwater - infiltratie - modellen - soil water movement - soil water - infiltration - models
    Congresverslag; afscheid van RA Feddes
    Actualisatie grondwaterdynamiek waterschap De Dommel
    Hoogland, T. ; Hoogerwerf, M.R. ; Kekem, A.J. van - \ 2004
    Wageningen : Alterra (Alterra-rapport 1008) - 44
    bodemwater - grondwaterstand - cartografie - monitoring - hydrodynamica - bodemwaterbeweging - uitspoelen - nederland - noord-brabant - soil water - groundwater level - mapping - monitoring - hydrodynamics - soil water movement - leaching - netherlands - noord-brabant
    Omdat de provinciale kartering van de grondwaterdynamiek (Gd) volgens het waterschap de Dommel vooral in de beekdalen te droog gekarteerde waarden liet zien, zijn in opdracht van het waterschap geactualiseerde ruimtelijke bestanden gemaakt van de gemiddelde hoogste, voorjaars- en laagste grondwaterstand (GHG, GVG en GLG) en van de grondwatertrap (Gt). Als basisinformatie zijn hierbij aanvullende incidentele metingen en tijdreeksen van grondwaterstanden gebruikt. Door toepassing van technieken uit de tijdreeksmodellering en regressietechnieken is een uniforme set puntschattingen van GHG, GVG en GLG verkregen. Deze gegevens zijn, gewogen naar kwaliteit, gebruikt om relaties met recent verzamelde hoogte-gegevens (het AHN) te leggen. Door gebiedsdekkende toepassing van deze relaties en een statistische foutencorrectie zijn gedetaileerde ruimtelijkebestanden verkregen met de resolutie van het AHN waarin GHG, GVG en GLG en hun voorspelfout worden weergegeven. De geactualiseerde Gd-kaart geeft vooral in de beekdalen een natter beeld dan de provinciale kartering en levert een groter nauwkeurigheid in de gekarteerde grondwaterdynamiek.
    Characterising groundwater dynamics based on a system identification approach
    Asmuth, J.R. von; Knotters, M. - \ 2004
    Journal of Hydrology 296 (2004)1-4. - ISSN 0022-1694 - p. 118 - 134.
    bodemwaterbeweging - monitoring - modellen - tijdreeksen - grondwaterspiegel - grondwaterstand - statistische analyse - soil water movement - monitoring - models - time series - water table - groundwater level - statistical analysis - water-table depths - time-series - seasonal fluctuation - soil maps - variables
    For visual interpretation, mapping or empirical modelling purposes, the amount of information contained in a full spatio-temporal description of the groundwater table dynamics is simply too large. For such purposes, the data has to be compressed without loosing too much information. Methods have been developed to visualise the groundwater regime in overall graphs, or statistically characterise the dynamics with a limited set of parameters. More recently, methods have been sought to identify the properties that determine the dynamics of a groundwater system. In such approaches, it is believed that the spatial differences in the groundwater dynamics are determined by the system properties, while its temporal variation is driven by the dynamics of the input into the system. In this paper, a method is presented that links the dynamics of the input to the spatially variable system properties, and results in a new set of parameters that characterise the groundwater dynamics (GD). While the dynamics of the input are characterised by its mean level and annual amplitude, the functioning of the groundwater system is characterised by its impulse response (IR) function. The IR function can for instance be estimated empirically using a time series model. Subsequently, the input and system characteristics are combined into a set of parameters that describe the output, or GD, using simple analytical expressions. It is shown that these so-called GD characteristics (the mean depth, convexity, annual amplitude and phase shift), can describe the GD in detail (for as far as the time series model can). In the example application, the GD characteristics are compared to other methods for characterising the groundwater regime, using two example series of groundwater level observations. It is shown that the so-called MxGL statistics (Mean Highest, Lowest or Spring Groundwater Level) that are often used have some important drawbacks, as they filter out the low-frequency dynamics of a system and mix-up annual with higher frequencies. Consequently, it is concluded that the capability of MxGL statistics in characterising the GD at different locations is less than that of GD characteristics.
    Grondwaterdynamiek in kaart en praktijk; symposium bundel
    Hoogland, T. ; Horst, J.B.F. van der - \ 2004
    Wageningen : Alterra (Alterra-rapport 899) - 33
    bodemwaterbeweging - grondwaterspiegel - uitspoelen - monitoring - modellen - bodemkarteringen - kaarten - soil water movement - water table - monitoring - models - leaching - soil surveys - maps
    Sinds 1997 is Alterra bezig met het ontwikkelen van een nieuwe methode en het uitvoeren van projecten om de grondwaterdynamiek (Gd) in kaart te brengen. De nieuwe methode om de grondwaterdynamiek in kaart te brengen is in opdracht van een aantal waterschappen, de provincie Noord-Brabant en het ministerie van LNV toegepast om de, veelal verouderde, Gt-informatie uit de bodemkaart 1: 50.000 te actualiseren. Gd-kaarten worden in het regionaal, provinciaal en landelijk beleid voor verschillende toepassingen gebruikt. Bij waterschappen en provincies worden Gd-kaarten gebruikt bij het vaststellen van het Gewenst Grond- en Oppervlaktewater Regime (GGOR) en voor regionaal waterbeheer. In het landelijk beleid wordt de Gd-kartering o.a. toegepast voor het vaststellen van uitspoelingsgevoelige gronden in het kader van de mestwetgeving. Na een aantal jaren van uitvoering van Gd-projecten voor verschillende opdrachtgevers leek het ons nuttig om met gebruikers en beoogd gebruikers van Gd-informatie van gedachten te wisselen over de gebruiksdoelen, gebruiksmogelijkheden en het omgaan met onzekerheid. Hiervoor hebben we drie (beoogd) gebruikers van Gd informatie uitgenodigd om op het symposium hun wensen en bevindingen te bespreken. De drie sprekers werken voor organisaties die op verschillende schaalniveau opereren en gebruik maken van Gd-informatie voor verschillende toepassingen. Hierdoor kwamen zeer uiteenlopende aspecten, die een rol spelen bij het gebruik van Gd-informatie, aan de orde en ontstond een levendige discussie. U treft in dit rapport een samenvatting van de verschillende voordrachten aan en een beknopt verslag van de discussie.
    Iron and sulphate as possible key factors in the restoration ecology of rich fens in discharge areas
    Kemmers, R.H. ; Delft, S.P.J. van; Jansen, P.C. - \ 2003
    Wetlands Ecology and Management 11 (2003)6. - ISSN 0923-4861 - p. 367 - 381.
    bodemchemie - veengronden - bodemwaterbeweging - calcium - zure gronden - soil chemistry - calcium - acid soils - peat soils - soil water movement
    Seven reference areas in the Netherlandswere selected to trial restoration measuresin acidified rich fens in discharge areas.In about half of the projects the measuresthat aimed to restore the high base statusof the topsoil failed. The aim of thepresent study was to identify the keyfactors and processes in base regulation ofrich fen systems, in order to underpinfuture restoration. We sampled soil andinterstitial water from distinct soilhorizons and analysed it for variablesinvolved in geohydrochemical processes. Wemonitored interstitial water chemistry andredox potentials to calibrate and validatea chemical speciation model, that we usedfor the interpretation of our observations.It appeared that soil pH, Ca2+saturation and iron contents weresignificantly lower at sites whererestoration efforts had failed. At the sametime, soils of these sites were verystratified instead of homogenous. Onlysoils with high iron contents recovered ahigh Ca2+ saturation. All sites werecharacterised by considerable downwardwater fluxes through the soil. Chemicalspeciation modelling was a useful tool forthe interpretation of processes underlyingour observations and helped elucidate thefactors and processes that control therecharge of the CEC by base cations. The modelling results suggested that the mainprocess in proton neutralisation ofsuccessful sites is the production ofinternal alkalinity by reduction of ironoxides. Additional redox capacity can besupplied by the ample presence ofsulphates. From our results we hypothesisethat the CEC will only be rechargedsuccessfully with base cations in thepresence of sufficient redox capacity ofthe soil. It seems that redox processesfacilitate the ionic exchange of protonsfor Ca2+ ions. Sites where restorationefforts failed changed from discharge areasto recharge areas, which caused irondepletion by leaching. We conclude thatproper understanding of the pedological andgeohydrochemical processes that control thebase status of soils is a prerequisite forsuccessful nature restoration. The role ofsoil processes cannot be ignored as itseems that the production of internalalkalinity upon reduction exceeds theexternal supply of alkalinity bygroundwater flow.
    Soil water - groundwater interaction
    Kroes, J.G. ; Dam, J.C. van - \ 2003
    In: Reference Manual SWAP; version 3.0.3 Wageningen : Alterra (Alterra-rapport 773) - p. 85 - 89.
    bodemwaterbeweging - grondwaterstroming - modellen - soil water movement - groundwater flow - models
    SWAP offers eight options to prescribe the lower boundary condition. These conditions are given in this chapter
    Soil water - surface water interaction
    Dam, J.C. van; Kroes, J.G. ; Groenendijk, P. ; Walsum, P.E.V. van - \ 2003
    In: Reference Manual SWAP; version 3.0.3 / Kroes, J.G., van Dam, J.C., Wageningen : Alterra (Alterra-rapport 773) - p. 51 - 83.
    bodemwaterbeweging - oppervlakkige afvoer - ondergrondse drainage - modellen - soil water movement - runoff - subsurface drainage - models
    Drainage and infiltration are described by Hooghoudt and Ernst equations;
    Water flow and solute transport in the Korenburgerveen site
    Rovdan, E. - \ 2003
    In: Measurement techniques and data assessment in wetlands hydrology / Ignar, S., Nowakowski, P., Okruszko, T., Warsaw : Warsaw Agricultural University Press - ISBN 9788372444868 - p. 103 - 115.
    veengronden - veengebieden - bodemwaterbeweging - uitspoelen - modellen - gelderland - achterhoek - peat soils - peatlands - soil water movement - leaching - models - gelderland - achterhoek
    This paper describes the results of investigation of water flow and tracer transport to estimate the effect of different water management scenarios, climatic conditions and restoration measure. The SWAP model was used in this study
    Nieuwe informatie over de grondwaterdynamiek: wensen en mogelijkheden
    Knotters, M. ; Hoogland, T. ; Gaast, J.W.J. van der - \ 2003
    Wageningen : Alterra (Alterra-rapport 548) - 50
    bodemwater - grondwaterspiegel - bodemwaterbeweging - monitoring - waterbalans - infiltratie - kwel - grondwaterstand - nederland - informatiebehoeften - soil water - water table - soil water movement - monitoring - information needs - water balance - infiltration - seepage - groundwater level - netherlands
    Medewerkers van vier verschillende waterschappen hebben in interviews hun wensen kenbaar gemaakt naar nieuwe informatie over de grondwaterdynamiek. De mogelijkheden om aan deze wensen te voldoen in systematische karteringen van de grondwaterdynamiek zijn geanalyseerd. In het Holocene deel van Nederland, met beheerste peilen, is behoefte naar informatie over de relatie tussen grondwaterstand en oppervlaktewaterstand, om het grondwaterafhankelijk peilbeheer af te kunnen stemmen op de risiconormering voor wateroverlast. Een ontwerp van een karteermethodiek is geschetst, waarin de inventarisatie van de opbolling van de grondwaterstand en de schatting van drainageweerstanden een belangrijke rol spelen.
    Transport of water, bromide ion, nutrients and the pesticides bentazone and imidacloprid in a cracking, tile drained clay soil at Andelst, the Netherlands
    Smelt, J.H. ; Hendriks, R.F.A. ; Pas, L.J.T. van der; Matser, A.M. ; Toorn, A. van den; Oostindie, K. ; Dijk-Hooijer, O.M. van; Boesten, J.J.T.I. ; Scorza Júnior, R.P. - \ 2003
    Wageningen : Alterra (Alterra-rapport 289) - 213
    uitspoelen - pesticiden - grondwaterverontreiniging - zware kleigronden - voedingsstoffen - bodemwaterbeweging - nitraten - bromide - bentazon - imidacloprid - nitraat - experimenteel veldonderzoek - nederland - leaching - pesticides - groundwater pollution - clay soils - nutrients - soil water movement - nitrates - bromide - bentazone - imidacloprid - nitrate - field experimentation - netherlands
    The aim of this study was to perform a field experiment to collect a high quality data set suitable for validating and improving pesticide leaching models and nutrient leaching models for drained and cracking clay soils. The transport of water, bromide, nutrients and the pesticides bentazone and imidacloprid was studied on a 1.2 ha experimental plot. Moisture profiles and groundwater tables were measured, starting in November 1997. Winter wheat was sown on 23 October 1997 and harvested on 20 August 1998. Bentazone and bromide were applied at 7 April 1998; imidacloprid was applied at 27 May when the soil was almost completely covered by the crop. The amount present in soil was measured within 2 days after application (32 sampling cores) and was found to vary between 80% of the nominal dose (imidacloprid) to 110 % (for bentazone). Manuring and soil cultivations were as usual for the wheat crop. Soil profiles were sampled at eight times (16 cores at each date, last in April 1999). Drain flow was continuously recorded and the water flow proportionally sampled for analysis of the test compounds. Groundwater was sampled periodically from sets of permanently placed filters at four depths at 16 sites. Sorption isotherms of the pesticides were measured with soil from 0-25 cm. Transformation rates of the pesticides were measured at different temperatures in soil material from topsoil and subsoil layers. Soil hydraulic properties and shrinkage characteristics were measured in the laboratory. Meteorological data (i.e. rainfall, air temperature, global radiation, air humidity etc.) groundwater levels and soil temperatures at three depths were monitored continuously. After 56 days, about 80% of the bromide dose was taken up by the crop, which demonstrates that bromide is not a suitable tracer in cropped soil during the growing season. After that time the bromide was gradually released again into the soil. Preferential transport through cracks and macropores of all test compounds was measured both in summer and in winter. This resulted in the highest concentration of bromide and bentazone measured in drain water already 21 days after application following 56 mm rainfall. Imidacloprid was already detected in groundwater at 1.3-1.5 m depth, 11 days after application, following 65 mm rainfall. High peaks in nitrate concentrations in the groundwater at 1.00-1.50 m depth and in the drain water were detected within 14-18 days after the first fertilizer application, following 94 mm of rainfall. Extreme high peaks in concentrations of ortho-P and soluble organic-P were measured in the drain water at respectively 2 days and 37 after slurry application (the only phosphorus application during the experiment). For nitrate concentrations in the drain water there were indications for bypass by preferential flow of `clean` rainwater to the drains.
    Developing and testing a regularization technique
    Loon, E.E. van; Troch, P.A.A. - \ 2003
    In: CAHMDA Workshop, Wageningen, September 2001 / E.E. van Loon and P.A. Troch Wageningen : Sub-department Water Resources - p. 67 - 89.
    bodemwaterbeweging - modellen - bodemwaterbalans - retentie - soil water movement - soil water balance - retention - models
    Investigation of the functional lifetime of TRISOPLASTr in relation to chemical compositions of pore water solutions in barriers
    Boels, D. ; Beest, H. te; Zweers, H. ; Groeneveld, P. - \ 2003
    Wageningen : Alterra (Alterra-rapport 528) - 49
    barrières - chemische samenstelling - permeabiliteit - bodemwaterbeweging - poriën - kationenwisseling - stortterreinen - bodembescherming - membraanpermeabiliteit - membranen - barriers - chemical composition - permeability - soil water movement - pores - cation exchange - landfills - soil conservation - membrane permeability - membranes
    Trisoplastr is a mixture of sand, bentonite and a polymer, used amongst others as landfill cover as well as barriers. Its permeability is generally lower than 1-2 x 10-11 m/s. Trisoplast keeps its functionality even in contact with different kinds of liquids, is not susceptible to cyclic drying and rewetting, and the permeability hardly depends on its dry bulk density. Tests with 10¿iaxial strain show only a slight increase in permeability. The functional lifetime of Trisoplast is governed by exchange of adsorbed sodium ions against dissolved calcium ions. This process depends on the composition of the pore water solution in the soil layers directly in contact with Trisoplast and the displacement rate of dissolved calcium ions either by convectiveor diffusive transport phenomena. The functional lifetime of Trisoplast even under relatively extreme conditions is at least 100 years and scores clearly better than the reference sand-bentonite barrier.
    Modelconcepten voor de interactie tussen verzadigd grondwater en oppervlaktewater
    Groenendijk, P. ; Lange, W.J. de; Kovar, K. - \ 2002
    Stromingen : vakblad voor hydrologen 8 (2002)2. - ISSN 1382-6069 - p. 11 - 28.
    grondwater - grondwaterstroming - bodemwaterbeweging - interacties - verzadigde stroming - modellen - drainage - groundwater - groundwater flow - soil water movement - drainage - interactions - saturated flow - models
    Uitgaande van de 3 kernbegrippen drainageflux, lekflux en voedingsflux is getracht een koppeling te vinden tussen het topsysteem en het diepe grondwater. Op weg naar deze koppeling zijn een aantal aannames gedaan
    Percolation Thresholds in 2-Dimensional Prefractal Models of Porous Media
    Sukop, M.C. ; Dijk, G.J. van; Perfect, E. ; Loon, W.K.P. van - \ 2002
    Transport in Porous Media 48 (2002). - ISSN 0169-3913 - p. 187 - 208.
    percolatie - bodemwaterbeweging - permeabiliteit - poreus medium - modellen - fractal meetkunde - porous media - percolation - soil water movement - permeability - models - fractal geometry
    Considerable effort has been directed towards the application of percolation theory and fractal modeling to porous media. We combine these areas of research to investigate percolation in prefractal porous media. We estimated percolation thresholds in the pore space of homogeneous random 2-dimensional prefractals as a function of the fractal scale invariance ratio b and iteration level i. The percolation thresholds for these simulations were found to increase beyond the 0.5927... porosity expected in Bernoulli (uncorrelated) percolation networks. Percolation in prefractals occurs through large pores connected by small pores. The thresholds increase with both b (a finite size effect) and i. The results allow the prediction of the onset of percolation in models of prefractal porous media and can be used to bound modeling efforts. More fundamental applications are also possible. Only a limited range of parameters has been explored empirically but extrapolations allow the critical fractal dimension to be estimated for a large combination of b and i values. Extrapolation to infinite iterations suggests that there may be a critical fractal dimension of the solid at which the pore space percolates. The extrapolated value is close to 1.89 - the well-known fractal dimension of percolation clusters in 2-dimensional Bernoulli networks.
    Overland flow: interfacing models with measurements
    Loon, E.E. van - \ 2002
    Wageningen University. Promotor(en): L. Stroosnijder; K.J. Keesman. - S.l. : S.n. - ISBN 9789058085580 - 171
    oppervlakkige afvoer - bodemwaterbeweging - hydraulisch geleidingsvermogen - modellen - runoff - soil water movement - hydraulic conductivity - models
    Index words: overland flow, catchment scale, system identification, ensemble simulations.

    This study presents new techniques to identify scale-dependent overland flow models and use these for ensemble-based predictions. The techniques are developed on the basis of overland flow, rain, discharge, soil, vegetation and terrain observations that were collected over a three year period in two tropical catchments. The merits of the identification technique are its robustness with regard to unknown errors, the ability to adjust model resolution in response to data availability, and to interpret the entities of the identified model structures physically. Compared to a static regression model and a dynamic distributed model the predictive performance of the scale-dependent overland flow models is good, especially when using model ensembles. Further analysis of the scale-dependent models shows that rainfall largely determines overland flow when modelled at coarse resolutions, whereas soil moisture drives overland flow when defined at fine resolutions. Interestingly, the number of model parameters remains constant over the different resolutions. The use of the scale-dependent models for predictive purposes is demonstrated by applying Tikhonov regularization for recursive state as well as parameter estimation.
    Modelling Water Flow and Solute Transport for Horticultural and Environmental Management
    Feddes, R.A. ; Dam, J.C. van - \ 2002
    Acta Horticulturae 573 (2002). - ISSN 0567-7572 - p. 107 - 117.
    grondwaterstroming - bodemwaterbeweging - simulatiemodellen - voedingsoplossingen - tuinbouw - agrarische bedrijfsvoering - milieubeheer - bodemoplossing - groei - bodemmorfologie - groundwater flow - soil water movement - simulation models - nutrient solutions - horticulture - farm management - environmental management - soil solution - growth - soil morphology
    During the past 10 years, the simulation model SWAP (Soil, Water, Atmosphere, Plant) was developed by the Sub-Department Water Resources of Wageningen University jointly with the Department Water and Environment of Alterra Green World Research. SWAP simulates vertical transport of water, solutes and heat in variably saturated, cultivated soils at field scale level and during whole growing seasons. Different versions of the model have been applied worldwide in research, education and as a decision support tool in the management of agricultural, horticultural and natural systems water flow in homogeneous and heterogeneous soils with or without the influence of groundwater. The main features of and theoretical concepts behind SWAP are described, in particular soil water flow, solute transport and crop growth.
    Water repellency of soils; the influence of ambient relative humidity
    Doerr, S.H. ; Dekker, L.W. ; Ritsema, C.J. ; Shakesby, R.A. ; Bryant, R. - \ 2002
    Soil Science Society of America Journal 66 (2002)2. - ISSN 0361-5995 - p. 401 - 405.
    bodemwater - afstoting - temperatuur - relatieve vochtigheid - meteorologie - bodemwaterbeweging - zandgronden - bodemfysica - bodemvocht - waterafstotendheid - soil water - repellency - temperature - relative humidity - meteorology - soil water movement - sandy soils
    Adverse effects of soil water repellency (hydrophobicity) are of concern during or following rainfall or irrigation, and are often preceded by conditions of high atmospheric relative humidity (RH). Assessments of repellency are, however, commonly conducted on air-dried samples at ambient laboratory conditions. This study explores the effects of differing antecedent RHs (32-98%) on the water repellency of air-dried soils of wide ranging characteristics under laboratory conditions using water drop penetration time (WDPT) and ethanol-percentage tests. Most samples exhibited considerably higher water repellency after exposure (< 1 d) to 98% RH compared with lower RHs, typical of ambient laboratory conditions. This work suggests that previous studies mayhave incorrectly classified some soils, likely to exhibit water repellency in the field, as wettable, and that tests carried out following exposure of samples to high RH provide assessments that best reflect critical field conditions.
    The solute leaching surface as a tool to assess the performance of multidimensional unsaturated solute transport models
    Rooij, G.H. de; Stagnitti, F. - \ 2002
    In: Computational methods in water resources : proceedings of the XIVth international conference on computational methods in water resources (CMWR XIV), June 23-28, 2002, Delft, The Netherlands. - - p. 639 - 646.
    bodemwaterbeweging - uitspoelen - hydraulisch geleidingsvermogen - modellen - ruimtelijke variatie - soil water movement - leaching - hydraulic conductivity - spatial variation - models
    Spatial and temporal distribution of solute leaching in heterogeneous soils: analysis and application to multisampler lysimeter data
    Rooij, G.H. de; Stagnitti, F. - \ 2002
    Journal of Contaminant Hydrology 54 (2002). - ISSN 0169-7722 - p. 329 - 346.
    bodemwaterbeweging - uitspoelen - hydraulisch geleidingsvermogen - modellen - ruimtelijke variatie - soil water movement - leaching - hydraulic conductivity - spatial variation - models
    Accurate assessment of the fate of salts, nutrients, and pollutants in natural, heterogeneous soils requires a proper quantification of both spatial and temporal solute spreading during solute movement. The number of experiments with multisampler devices that measure solute leaching as a function of space and time is increasing. The breakthrough curve (BTC) can characterize the temporal aspect of solute leaching, and recently the spatial solute distribution curve (SSDC) was introduced to describe the spatial solute distribution. We combined and extended both concepts to develop a tool for the comprehensive analysis of the full spatio-temporal behavior of solute leaching
    Inversely estimating soil hydraulic functions using evapotranspiration fluxes
    Jhorar, R.K. ; Bastiaanssen, W.G.M. ; Feddes, R.A. ; Dam, J.C. van - \ 2002
    Journal of Hydrology 258 (2002). - ISSN 0022-1694 - p. 198 - 213.
    bodemwaterbeweging - hydraulisch geleidingsvermogen - evapotranspiratie - modellen - soil water movement - hydraulic conductivity - evapotranspiration - models
    Modeling the sink term under variable soil water osmotic and pressure heads
    Homaee, M. ; Feddes, R.A. - \ 2002
    In: Computational Methods in Water Resources : XIVth International Conference on Computational Methods in Water Resources , Delft, June 23-28, 2002 / Majid Hassanizadeh, S., Schotting, Ruud J., Gray, William G., Pinder, George F., Elsevier - ISBN 9780444509758 - p. 17 - 24.
    bodemwatergehalte - bodemwaterbeweging - plant-water relaties - modellen - hydraulisch geleidingsvermogen - soil water content - soil water movement - hydraulic conductivity - plant water relations - models
    Chloride transport in a recently reclaimed Dutch polder
    Vos, J.A. de; Raats, P.A.C. ; Feddes, R.A. - \ 2002
    Journal of Hydrology 257 (2002). - ISSN 0022-1694 - p. 59 - 77.
    bodemwaterbeweging - drainage - ontginning - polders - grondwaterspiegel - waterkwaliteit - chloride - modellen - flevoland - soil water movement - water table - water quality - chloride - drainage - reclamation - polders - models - flevoland
    Tikhonov regularization as a tool for assimilating soil moisture data in distributed hydrological models
    Loon, E.E. van; Troch, P.A. - \ 2002
    Hydrological Processes 16 (2002). - ISSN 0885-6087 - p. 531 - 556.
    bodemwatergehalte - bodemwaterbeweging - hydrologie van stroomgebieden - modellen - ruimtelijke variatie - geostatistiek - soil water content - soil water movement - catchment hydrology - spatial variation - models - geostatistics
    Discharge, water table depth, and soil moisture content have been observed at a high spatial and temporal resolution in a 44 ha catchment in Costa Rica over a period of 5 months. On the basis of the observations in the first 3 months (period A), two distinct soil moisture models are identified and calibrated: a linear stochastic time-varying state-space model, and a geo-statistical model. Both models are defined at various spatial and temporal resolutions. For the subsequent period of 2 months (period B), four different ways to predict the soil moisture dynamics in the catchment are compared: (1) the application of the dynamic models in open-loop form; (2) a re-calibration of the dynamic models with soil moisture data in period B, and subsequent prediction in open-loop form; (3) prediction with the geo-statistical models, using the soil moisture data in period B; (4) prediction by combining the outcomes of (1) and (3) via generalized cross-validation. The last method, which is a form of data assimilation, compares favourably with the three alternatives. Over a range of resolutions, the predictions by data assimilation have overall uncertainties that are approximately half that of the other prediction methods and have a favourable error structure (i.e. close to Gaussian) over space as well as time. In addition, data assimilation gives optimal predictions at finer resolutions compared with the other methods. Compared with prediction with the models in open-loop form, both re-calibration with soil moisture observations and data assimilation result in enhanced discharge predictions, whereas the prediction of ground water depths is not improved
    Waterretentie- en doorlatendheidskarakteristieken van boven- en ondergronden in Nederland: de Staringreeks; vernieuwde uitgave 2001
    Wösten, J.H.M. ; Veerman, G.J. ; Groot, W.J.M. de; Stolte, J. - \ 2001
    Wageningen : Alterra (Alterra-rapport 153) - 86
    bodemwaterbeweging - hydraulisch geleidingsvermogen - beschikbaar bodemwater - hysterese - pf-curve - soil water movement - hydraulic conductivity - available water - hysteresis - pf-curve
    Het bij Alterra aanwezige bestand van gemeten bodemfysische karakteristieken is de laatste jaren aanzienlijk uitgebreid. Deze uitbreiding heeft geleid tot een vernieuwing van de in 1994 uitgebrachte Staringreeks. De Staringreeks vermeldt de gemiddeldebodemfysische karakteristieken voor alle onderscheiden 18 boven- en 18 ondergronden. De reeks geeft een complete landelijke dekking van alle op de Bodemkaart van Nederland 1 : 50 000 onderscheiden bodemeenheden. Om het gebruik van de bodemfysische karakteristieken in simulatiemodellen te vereenvoudigen zijn de karakteristieken beschreven met analytische vergelijkingen. Tevens is een programma beschikbaar waarmee de gebruiker aan de hand van de bodemkenmerken textuur, organischestofgehalte, dichtheid, boven- of ondergrond met behulp van continue vertaalfuncties voorspellingen kan maken van de bodemfysische karakteristieken.
    Irrigation practices affecting land degradation in Sicily
    Crescimanno, G. - \ 2001
    Wageningen University. Promotor(en): J. Bouma; H.W.G. Booltink. - S.l. : S.n. - ISBN 9789058084262 - 169
    irrigatie - bodemwaterbeweging - bodemzoutgehalte - bodemdegradatie - scheurvorming - italië - irrigation - soil water movement - soil salinity - soil degradation - cracking - italy

    The available amount of fresh water for agriculture, and specifically for irrigation, is decreasing all over the world. The quality of irrigation water is deteriorating, and saline/sodic waters are increasingly used in many arid and semi-arid regions of the world. Salinization is closely associated with the process of desertification.

    Sustainable land management practices are urgently needed to preserve the production potential of agricultural land while safeguarding environmental quality. In cracking soils sustainable management should take into account the occurrence of bypass flow and the influence that land use may have on soil structure and bypass flow phenomena.

    Measurement of vertical and horizontal shrinkage in confined soil cores was found to be suitable for determining the Soil Shrinkage Characteristic Curve (SSCC) and for incorporating shrinkage in the soil hydraulic parameters/functions determined on confined undisturbed soil samples. An optimization procedure based on multi-step outflow experiments with inverse modelling was developed for determining the soil hydraulic characteristics (HC). The need for accounting for structural porosity and shrinkage processes was recognized on the basis of hydraulic conductivity values determined by the suction crust infiltrometer method and of the SSCC determined on confined soil cores.

    Analysis of the response of clay soils to ESP values up to 15, showed that the concept of critical threshold needs reconsideration, because increasing soil degradation upon increasing ESP appeared to be a continuum. A major hazard of deterioration of structural and hydraulic properties was recognized even at low ESP values (ESP<5) in dilute solutions. In addition, the major influence that reductions in hydraulic conductivity due to salinity and/or sodicity may have in water transport in the soil-crop system was also documented by application of the LEACHM model.

    The relevance of bypass flow on the water balance in a Mediterranean climatic context as that occurring in Sicily, was evaluated by application of the FLOCR model. The results showed that bypass flow corresponded with about 70-74% of cumulative yearly rainfall, and that models not accounting for bypass flow may lead to a significant overprediction of crop evapotranspiration and underestimation of the hazard of land degradation and desertification.

    Results of bypass flow measurements performed in a Mediterranean cracking soil under alternated use of a high salinity solution to distilled water showed that exchange of solutes occurred at the contact surfaces between the macropores/cracks walls and the incoming solution in concomitance with bypass fluxes. These exchanges were effective in determining leaching of solutes and removal of Sodium, and in preventing salinization and sodification in part of the soil volume that is in contact with the roots.

    Combined use of morphometric and physical techniques made it possible to explore the effect of irrigation on soil structure and bypass flow phenomena of a Mediterranean cracking soil under two different irrigation systems, i.e. drip and micro-sprinkler. Different vertical distributions of cracks was found under the two irrigation systems. In agreement with these observations, different flow behaviour was observed in the laboratory in cylindrical soil cores taken from the irrigated micro-sprinkler field. No bypass flow or lower amounts of bypass flow in the micro-sprinkler irrigated field compared to the drip irrigation treatment. Chemical dispersion of clay particles and detachment of these particles from the surface and their movement into the cracks were the mechanisms responsible for the partial or total occlusion of the (macro) pores in the micro-sprinkler irrigated field.

    In conclusion, this study showed that drip irrigation alternatively using high and low salt water was most effective in maintaining the productive capacity of the clay soil being studied, particularly when this water was applied to a cracked soil. Combined use of morphometric and physical methods was necessary to understand the underlined highly dynamic flow behaviour in these complex soils.

    Evaluating drainage design parameters for the Fourth Drainage Project, Pakistan by using SWAP model: Part II - modeling results
    Sarwar, A. ; Feddes, R.A. - \ 2000
    Irrigation and Drainage Systems 14 (2000). - ISSN 0168-6291 - p. 281 - 299.
    drainage - ontwerp - buisdrainage - bodemwaterbeweging - uitspoelen - verzilting - modellen - pakistan - drainage - design - tile drainage - soil water movement - leaching - salinization - models - pakistan
    Evaluating drainage design parameters for the fourth drainage project, Pakistan by using SWAP model: Part I - calibration
    Sarwar, A. ; Bastiaanssen, W.G.M. ; Boers, T.M. ; Dam, J.C. van - \ 2000
    Irrigation and Drainage Systems 14 (2000). - ISSN 0168-6291 - p. 257 - 280.
    drainage - buisdrainage - bodemwaterbeweging - uitspoelen - verzilting - modellen - pakistan - ontwerp - drainage - design - tile drainage - soil water movement - leaching - salinization - models - pakistan
    Spatial variability of solute leaching : experimental validation of a quantitative parameterization
    Rooij, G.H. de; Stagnitti, F. - \ 2000
    Soil Science Society of America Journal 64 (2000)2. - ISSN 0361-5995 - p. 499 - 504.
    bodemoplossing - bodemwaterbeweging - uitspoelen - modellen - ruimtelijke variatie - soil solution - soil water movement - leaching - spatial variation - models
    Soil heterogeneity, soil structure, and fingered flow affect solute leaching from the vadose zone to the ground water. Recently, the spatial variation of cumulative solute fluxes at a given depth was characterized by fitting the two-parameter beta distribution to sorted amounts of solute leaching at different sampling points. We tested this parameterization on data from a chloride tracer experiment performed on a monolith lysimeter, below which drainage was collected from 300 compartments with a combined area of 0.75 m2. The effect of total sampling area, sample size, and the number of samples and their spatial distribution (random locations vs. clustered) on the fitted parameters was examined. Sixteen or more sampling locations of 25 cm2 each (5% of the total area) resulted in adequate representation of parameter values. Increasing the sample size underestimated the degree of heterogeneity. We therefore recommend that the fitted parameter values of the beta distribution be reported together with the sample size. In solute-transport experiments, collecting many small samples will give more accurate results than taking fewer but larger samples. | Soil heterogeneity, soil structure, and fingered flow affect solute leaching from the vadose zone to the ground water. Recently, the spatial variation of cumulative solute fluxes at a given depth was characterized by fitting the two-parameter beta distribution to sorted amounts of solute leaching at different sampling points. We tested this parameterization on data from a chloride tracer experiment performed on a monolith lysimeter, below which drainage was collected from 300 compartments with a combined area of 0.75 m2. The effect of total sampling area, sample size, and the number of samples and their spatial distribution (random locations vs. clustered) on the fitted parameters was examined. Sixteen or more sampling locations of 25 cm2 each (5% of the total area) resulted in adequate representation of parameter values. Increasing the sample size underestimated the degree of heterogeneity. We therefore recommend that the fitted parameter values of the beta distribution be reported together with the sample size. In solute-transport experiments, collecting many small samples will give more accurate results than taking fewer but larger samples.
    Nitraattransport naar de wortels door de neerwaartse waterstroming in de grond bij in kassen geteelde tomaten ; een simulatie
    Ende, J. van den; Kipp, J.A. - \ 1998
    Naaldwijk : Proefstation voor Bloemisterij en Glasgroente, Vestiging Naaldwijk (Rapport / Proefstation voor Bloemisterij en Glasgroente 132) - 45
    nitraten - plantenvoeding - voedingsstoffentransport - bodemwaterbeweging - toevloei naar wortels - simulatiemodellen - nitrates - plant nutrition - nutrient transport - soil water movement - flow to roots - simulation models
    Voor teelten van tomaten in kassen waarbij bij het fertigeren een doorspoelfractie van 0.25 wordt aangehouden, is het potentiële belang van de neerwaartse waterstroming in de grond voor het transport van nitraat naar de wortel nagegaan. Voor dit doel is een simulatie van die stroming uitgevoerd met behulp van het model SWACROP. Uit de hierbij verkregen snelheid van de neerwaartse waterstroming en de nitraatconcentratie van de bodemoplossing is de snelheid van het neerwaartse nitraattransport afgeleid en vergeleken met een schatting van de door de plant benodigde nitraatopnameflux aan het worteloppervlak. De diverse gebruikte basisgegevens worden omschreven en toegelicht. De verkregen resultaten worden vanuit verschillende gezichtspunten bediscussieerd. Zij maken het aannemelijk dat, althans gedurende de produktiefase van het gewas, bij genoemde teelten het vereiste nitraattransport naar de wortel grotendeels voor rekening van de neerwaartse waterstroming kan komen.
    Three-dimensional patterns of moisture, water repellency, bromide and pH in a sandy soil
    Ritsema, C.J. ; Dekker, L.W. - \ 1998
    Journal of Contaminant Hydrology 31 (1998)3/4. - ISSN 0169-7722 - p. 295 - 313.
    bodemwaterbeweging - hydraulisch geleidingsvermogen - bodemwater - infiltratie - zandgronden - tracers - bromide - ph - soil water movement - hydraulic conductivity - soil water - infiltration - sandy soils - tracers - bromide - ph
    Sprinkling of grassland. Fundamentals of soil water flow at the experimenta field
    Boheemen, P.J.M. van; Humbert, H. - \ 1984
    Wageningen : ICW (Nota / Instituut voor Cultuurtechniek en Waterhuishouding 1540) - 50
    beregening - graslanden - bodemwaterbeweging - overhead irrigation - grasslands - soil water movement
    De bepaling van de transporttijd van het grondwater bij stroming in de verzadigde zone
    Ernst, L.F. - \ 1973
    Wageningen : I.C.W. (Nota / Instituut voor Cultuurtechniek en Waterhuishouding 755) - 42
    grondwaterstroming - transportprocessen - snelheid - grondwater - concentratie - verzadigde stroming - bodemwaterbeweging - geohydrologie - groundwater flow - transport processes - velocity - groundwater - concentration - saturated flow - soil water movement - geohydrology
    De stroming van het grondwater wordt zeer dikwijls gezien als een drainageprobleem, waarbij het van belang is iets te weten van de hoeveelheid water, die per tijdseenheid door het beschouwde gebied stroomt, van de bergingsveranderingen in dit gebied en van de corresponderende potentiaalverschillen. Het kan ook van belang zijn iets te weten omtrent het transport van opgeloste stoffen en wel in het bijzonder in die gevallen dat de concentratie van de opgeloste stof niet constant is, maar afhangt van plaats en tijd. Als voorbeelden van dergelijke gevallen kunnen worden genoemd: zoute kwel in kustgebieden; infiltratie van water door middel van diepe putten of open leidingen met hoog peil, waarbij infiltratiewater en oorspronkelijk grondwater in het algemeen enig verschil in samenstelling hebben;uitspoe1ing van verzilte gronden door irrigatie met zout water, transport van meststoffen, insecticiden enz., die door het neerslagoverschot in de grondwaterstroom terecht komen. Bij deze problemen wordt gevraagd naar de snelheid waarmee het grondwater zich beweegt en naar de tijd, die het grondwater nodig heeft om het beschouwde gebied geheel of gedeeltelijk te doorlopen.
    Mull and mor (Mueller - Hesselman) in relation to the soil water regime of a forest
    Minderman, G. - \ 1960
    Arnhem : [s.n.] (Mededeling / Instituut voor toegepast biologisch onderzoek in de natuur. ITBON no. 49) - 27
    klimaat - bosbouw - humus - uitspoelen - strooisel - bodemvorming - bodemwaterbeweging - climate - forestry - humus - leaching - litter (plant) - soil formation - soil water movement
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