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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    We will mail you new results for this query: keywords==hydraulisch geleidingsvermogen
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Determining the saturated vertical hydraulic conductivity of retention basins in the Oum Zessar watershed, Soutern Tunisia
Bosch, S. van den; Hessel, R. ; Ouessar, M. ; Zerrim, A. ; Ritsema, C.J. - \ 2014
Wageningen/Médenine : Alterra, Wageningen/Institut des Régions Arides, Tunisia (Report / WAHARA number 22) - 136
waterbeheer - stroomgebieden - hydraulisch geleidingsvermogen - tunesië - water management - watersheds - hydraulic conductivity - tunisia
Unsaturated hydraulic properties of xerophilous mosses: towards implementation of moss covered soils in hydrological models
Voortman, B.R. ; Bartholomeus, R.P. ; Bodegom, P.M. van; Gooren, H.P.A. ; Zee, S.E.A.T.M. van der; Witte, J.P.M. - \ 2014
Hydrological Processes 28 (2014)26. - ISSN 0885-6087 - p. 6251 - 6264.
evaporatie - bryophyta - hydraulisch geleidingsvermogen - korstmossen - mossen - hydrologie - waterbalans - bodemwaterretentie - modelleren - evaporation - bryophyta - hydraulic conductivity - lichens - mosses - hydrology - water balance - soil water retention - modeling - sphagnum moss - water - conductivity - bryophytes - desiccation - ecosystems - tolerance
Evaporation from mosses and lichens can form a major component of the water balance, especially in ecosystems where mosses and lichens often grow abundantly, such as tundra, deserts and bogs. To facilitate moss representation in hydrological models, we parameterized the unsaturated hydraulic properties of mosses and lichens such that the capillary water flow through moss and lichen material during evaporation could be assessed. We derived the Mualem-van Genuchten parameters of the drying retention and the hydraulic conductivity functions of four xerophilous moss species and one lichen species. The shape parameters of the retention functions (2.17¿
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.
Hydraulic properties of Zinnia elegans : from cellular development in vitro to performance in planta
Twumasi, P. - \ 2007
Wageningen University. Promotor(en): Anne Mie Emons; Olaf van Kooten, co-promotor(en): Wim van Ieperen; Jan Schel. - [S.l.] : S.n. - ISBN 9789085046585 - 160
zinnia elegans - water - xyleem - hydraulisch geleidingsvermogen - snijbloemen - plant-water relaties - temperatuur - osmolariteit - osmose - apoptose - in vitro kweek - zinnia elegans - water - xylem - hydraulic conductivity - cut flowers - plant water relations - temperature - osmolarity - osmosis - apoptosis - in vitro culture
De doorlatendheid van de bodem voor infiltratiedoeleinden; een gebiedsdekkende inventarisatie voor het Waterschap Peel en Maasvallei
Massop, H.T.L. ; Gaast, J.W.J. van der; Kiestra, E. - \ 2005
Wageningen : Alterra (Alterra-rapport 1212) - 95
permeabiliteit - infiltratie - hydraulisch geleidingsvermogen - kwel - watervoerende lagen - grondwaterstroming - fysische bodemeigenschappen - grondwater - geohydrologie - limburg - permeability - infiltration - hydraulic conductivity - groundwater - mapping - seepage - aquifers - groundwater flow - geohydrology - limburg
In opdracht van waterschap Peel en Maasvallei is een onderzoek uitgevoerd naar de geohydrologische eigenschappen van het topsysteem. Het waterschap gebruikt deze informatie bij de beoordeling en advisering ten behoeve van infiltratievoorzieningen. Voor de beoordeling van deze voorziening zijn de doorlatendheid en de dikte van de deklaag van belang alsook het doorlaatvermogen van het onderliggende watervoerende pakket. Voor het gebiedsdekkend vaststellen van de eigenschappen is het gebied geschematiseerd in 60 eenheden op basis van bodemeigenschappen en opbouw diepere ondergrond. Aan deze eenheden is een k-waardetabel gekoppeld. Deze tabel is gebaseerd op beschikbare metingen en schattingen en aangevuld met metingen die in het kader van dit onderzoek zijn uitgevoerd. Naast k-waarden is een diktekaart van de deklaag vervaardigd op basis van bruikbare boringen. Het doorlaatvermogen van het eerste watervoerend pakket is afgeleid uit verschillende bronnen, waaronder pompproeven. Een belangrijk punt bij gebruik van de geïnventariseerde gegevens is de anisotropie van de deklaag als gevolg van het voorkomen van klei, leem of veenlagen
Karteren van de grondwaterdynamiek in gebieden met een klei deklaag; parameters voor grondwaterafhankelijk peilbeheer
Hoogland, T. ; Visschers, R. ; Gaast, J.W.J. van der; Knotters, M. - \ 2005
Wageningen : Alterra (Alterra-rapport 1127) - 40
bodemwaterregimes - hydraulisch geleidingsvermogen - drainage - zware kleigronden - grondwaterspiegel - land van maas en waal - peilbeheer - soil water regimes - hydraulic conductivity - water table - clay soils - water level management
Het doel van dit project is te onderzoeken hoe de relatie tussen grond- en oppervlaktewaterstand gebiedsdekkend kan worden beschreven in klei gebieden en hoe deze relatie gebruikt kan worden in een Gd-kartering. Een belangrijk aspect daarbij is de keuze van een meetnetopzet waarmee de relatie tussen grondwaterstand en oppervlaktewaterstand met een minimale meetinspanning zo goed mogelijk kan worden vastgesteld. In drie percelen in het komgebied van het land van Maas en Waal zijn de grond- en oppervlakte¬waterstand automatisch geregistreerd in raaien. De opbollings¬profielen in de drie raaien verschillen behoorlijk, ondanks hun korte onderlinge afstand in een vergelijkbaar landschap. De drainageweerstand, berekend uit het gemiddeld opbollings¬profiel over een stationaire periode, sluit het best aan bij de hydrologische definitie. De aldus berekende drainageweerstanden variëren met een factor twee, afhankelijk van de periode waarover berekening plaatsvindt. Ook de drainageweerstand, geschat uit gekalibreerde tijdreeksparameters, blijkt te variëren, afhankelijk van het kalibratiealgoritme en de tijdstap van het model en is daarom minder geschikt voor toepassing in een grootschalige Gd-kartering. Drainageweerstanden, geschat uit opbollingen over een veertiendaagse periode waarvan niet zeker is of stationariteit kan worden verondersteld, zijn vergelijkbaar met schattingen uit opbollingen over een stationaire periode. Hieruit blijkt dat de drainageweerstand ook op basis van slechts twee meettijdstippen mogelijk is. Dit is aantrekkelijk voor toepassing in een grootschalige Gd-kartering.
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
Drainage-water travel times as a key factor for surface water contamination
Groenendijk, P. ; Eertwegh, G.A.P.H. van den - \ 2004
In: Unsaturated-zone modeling: progress, challenges and applications. - Dordrecht [etc.] : Kluwer (Wageningen UR Frontis Series 6) - ISBN 9781402029189 - p. 145 - 178.
grondwaterstroming - grondwaterverontreiniging - oppervlaktewater - hydraulisch geleidingsvermogen - modellen - groundwater flow - groundwater pollution - surface water - hydraulic conductivity - models
The importance of the unsaturated zone as an inextricable part of the hydrologic cycle has long been recognized. The root zone and the unsaturated sub-surface domain are chemically and biologically the most active zones. The interrelationships between soil, subsoil and surface waters make it unrealistic to treat the saturated and unsaturated zones and the discharge to surface waters separately. Point models describe vertical water flow in the saturated zone and possibly lateral flow by defining a sink term. To account for the influence of two- and three-dimensional water flow on the travel-time distribution a conceptualization of the flow field is required. A formulation for upscaling the groundwater flow field is presented which yields the average vertical flux as a key factor for describing the travel time implicitly. Analytical solutions are given for the upscaled description for the transport; they are applied to a simple model consisting of a cascade of reservoirs. The analytical approach given, which includes the main properties of the soil system as well as the drainage system, proves to be useful for the prediction of solute concentrations in exfiltrating groundwater. The use and significance of conceptual models is discussed as well as the opportunities of detailed mechanistic integrated models that treat the unsaturated/saturated zone, overland flow and surface water flow comprehensively. Some results of experimental field work on the assessment of drainage water quality impacts of agricultural land management are summarized. Strengths, weaknesses, opportunities and threats of different modeling approaches are discussed. The unsaturated zone is an essential link in the chain between land management practices and the ecological status of freshwaters.
Bodemfysische karakterisering van gronden in het waterschap Rijn & IJssel; een bodemfysische schematisatie op basis van bodemkaarten
Thijssen, G.L. - \ 2004
Wageningen : Alterra (Alterra-rapport 924) - 205
bodemstructuur - bodemwater - hydraulisch geleidingsvermogen - bodemkarteringen - kaarten - gelderland - soil structure - soil water - hydraulic conductivity - soil surveys - maps
Voor de bodemfysische karakterisering van gronden in het waterschap Rijn & IJssel is gebruikt gemaakt van De Bodemkaart van Nederland, schaal 1 : 50 000 en verschillende detailbodem¬kaarten, schaal 1 : 10 000. Eenheden van bodemkaarten met bodemfysisch verwante eigenschappen zijn gegeneraliseerd tot bodemfysische eenheden. Van deze eenheden zijn gestan¬daardiseerde profielbeschrijvingen gemaakt, waarin de opeenvolging van de verschillende bodemhorizonten staan beschreven. De onderscheiden horizonten zijn vertaald naar bodem¬fysische bouwstenen uit de Staringreeks. Door deze link is het mogelijk de bodemfysische karakteristieken ruimtelijk weer te geven, en op die manier gebiedsdekkend toepasbaar te maken voor simulatiemodellen. Het resultaat bestaat uit 2 bodemfysische-eenhedenkaarten; één op basis van de Bodemkaart van Nederland, schaal 1 : 50 000, en één bodemfysische-eenhedenkaart op basis van de beschikbare detailbodemkaarten, schaal 1 : 10 00. Door het globale karakter van de gestandaardiseerde profielbeschrijvingen en de Staringreeks, is de informatie alleen geschikt voor toepassingen op regionaal niveau. Voor lokale toepassingen zijn meer gedetailleerde en gebiedspecifieke gegevens nodig.
Soil water repellency; occurrence, consequences, and amelioration
Ritsema, C.J. ; Dekker, L.W. - \ 2003
Amsterdam : Elsevier - ISBN 9780444512697 - 352
bodemwater - afstoting - bevochtigbaarheid - hygroscopiciteit - dehydratie - bodemstructuur - fysische bodemeigenschappen - hydraulisch geleidingsvermogen - soil water - repellency - wettability - hygroscopicity - dehydration - soil structure - soil physical properties - hydraulic conductivity
Land-use induced spatial heterogeneity of soil hydraulic properties on the Loess Plateau in China
Stolte, J. ; Venrooij, B. van; Zhang Guanghui, ; Trouwborst, K.O. ; Liu Guobin, ; Ritsema, C.J. ; Hessel, R. - \ 2003
Catena 54 (2003)1-2. - ISSN 0341-8162 - p. 59 - 76.
lössgronden - landgebruik - hydraulisch geleidingsvermogen - china - infiltratie - loess soils - land use - infiltration - hydraulic conductivity - china - erosion model - drainage basins - surface runoff - single-event - variability - conductivity - sensitivity - macropores - tillage
On the Loess Plateau in China, soil erosion amounts to between 10 000 and 25 000 tons/km2/year. In 1998, the EROCHINA project was started, with the major objective of developing alternative land-use and soil and water conservation strategies for the Loess Plateau, using the LISEM soil erosion model. In order to provide the model with accurate input on soil hydraulic properties of the catchment, this study tried to quantify these properties for major land-use units and to examine the effects of the statistically identified in-field heterogeneity on model outcome. The study area (Danangou catchment) is located in the middle part of the Loess Plateau in the northern part of Shaanxi Province. The catchment is about 3.5 km2 in size. To determine the hydraulic properties of the soil, a sampling scheme was implemented to measure unsaturated conductivity and water retention characteristics. The saturated conductivity measurements were performed on land-use clusters, based on treatment and plant and soil differences. A 100×100 m sampling grid was set out on 12 fields, with 1×1 m grid squares. On each field, 10 sampling spots were randomly selected, using Simple Random Sampling. The sensitivity of the LISEM model to the measured heterogeneity of saturated conductivity was analysed by using the geometric mean and standard deviation (S.D.) of the Ks-optimized of the various land-use units to calculate discharge and soil loss during a single rain event. This proved that, using the standard deviation of the saturated conductivity, which was 30¿50%, the calculated discharge and total sediment losses varied by a factor 2. Using the standard deviation had a minor effect on the calculated sediment concentration. As regards the on-site effects, the use of the geometric mean of Ks minus the S.D. resulted in an increase in the level of erosion, while the use of geometric mean of Ks plus the S.D. value resulted in a significant decrease in erosion level relative to that obtained using the geometric mean of Ks itself. Using randomly selected sampling spots and a calibration procedure as was done in the present study make detailed information on Ks available, which can be used to compare alternative land-use options for their effectiveness in reducing discharge and sediment losses.
Soil heterogeneity
Dam, J.C. van; Hendriks, R.F.A. - \ 2003
In: Reference Manual SWAP; version 3.0.3 / Kroes, J.G., van Dam, J.C., Wageningen : Alterra (Alterra-rapport 773) - p. 91 - 113.
bodemwater - infiltratie - hydraulisch geleidingsvermogen - modellen - ondergrondse drainage - ruimtelijke variatie - soil water - infiltration - hydraulic conductivity - subsurface drainage - models - spatial variation
Water and salt balances at farmer fields
Khatri, R.S. ; Dam, J.C. van; Jhorar, R.K. - \ 2003
In: Water productivity of irrigated crops in Sirsa district, India / van Dam, J.C., Malik, R.S., Wageningen : Wageningen UR - p. 41 - 58.
irrigatie - bodemwaterbalans - bodemchemie - verzilting - modellen - india - hydraulisch geleidingsvermogen - irrigation - soil water balance - hydraulic conductivity - soil chemistry - salinization - models
In this chapter the agrohydrological model SWAP is used to analyse the water flow and salt transport at the measured farmer fields
Simulation of soil water regimes including pedotransfer functions and land-use related preferential flow
Sonneveld, M.P.W. ; Backx, M.A.H.M. ; Bouma, J. - \ 2003
Geoderma 112 (2003). - ISSN 0016-7061 - p. 97 - 110.
bodemwater - hydraulisch geleidingsvermogen - waterafstotende gronden - modellen - soil water - hydraulic conductivity - water repellent soils - models - repellent sandy soil - unsaturated soil - movement
Differences in land use history among taxonomically identical soils often result in different hydraulic properties, derived from either laboratory measurements or pedotransfer functions (PTFs). Additionally, flow mechanisms in sandy soils may also change through differences in water repellency associated with land use history. The soil water regimes for three sandy soils of the same taxonomic unit and under pasture but with differences in land use history were simulated. The land use histories were old grassland (site A), recently reseeded grassland (site B) and previous maize-cultivated land (site C). Degrees of water repellency, as indicated by the Water Drop Penetration Time (WDPT) test, were found to be highest for the topsoil of sites A and B. Initial simulations, using continuous pedotransfer functions to derive the Mualem-Van Genuchten parameters, corresponded poorly with field measurements (TDR). Additional laboratory measurements did not result in a better correspondence. Taking account of preferential flow in sites A and B, using the mobile/immobile concept, improved modelling performance significantly. Model simulations for a limited time period showed that water storage in the top 50 cm was on average 59 mm higher for site C compared with site A, and 23 mm higher for site B compared with site A. Downward fluxes at 50-cm depth were especially larger for site A compared with sites B and C. (C) 2002 Elsevier Science B.V All rights reserved.
Waterretentie en waterdoorlatendheidskarakteristieken van TmT-proefvelden in Meterik en Vredepeel
Vos, J.A. de; Hummelink, E.W.J. ; Steenbergen, T.S. van - \ 2002
Wageningen : Plant Research International (Telen met toekomst OV 0204) - 24
bodemwater - bodemwaterretentie - hydraulisch geleidingsvermogen - bodemfysica - nederland - limburg - de peel - soil water - soil water retention - hydraulic conductivity - soil physics - netherlands - limburg - de peel
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.
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
Estimation of effective soil hydraulic parameters for water management studies in semi-arid zones : integral use of modelling, remote sensing and parameter estimation
Jhorar, R.K. - \ 2002
Wageningen University. Promotor(en): R.A. Feddes; W.G.M. Bastiaansen; J.C. van Dam. - S.l. : S.n. - ISBN 9789058086440 - 158
waterbeheer - irrigatie - bodemfysica - hydraulisch geleidingsvermogen - schatting - remote sensing - wiskundige modellen - integratie - optimalisatiemethoden - india - water management - irrigation - soil physics - hydraulic conductivity - estimation - remote sensing - mathematical models - integration - optimization methods - india

Key words: evapotranspiration, effective soil hydraulic parameters, remote sensing, regional water management, groundwater use, Bhakra Irrigation System, India.

The meaningful application of water management simulation models at regional scale for the analysis of alternate water management scenarios is often hindered by the lack of required input data. Especially information on relevant soil hydraulic parameters is required for the successful application of these models. The focus of this study is the development of techniques to determine effective regional soil hydraulic parameters by making integral use of simulation models, remote sensing information and parameter estimation procedures. The Sirsa Irrigation Circle, covering an area of 0.48 million ha, located in the Bhakra Irrigation system in the North West India is used as a case study.

Forwards and backward simulations with the SWAP model for homogeneous soil profiles proved that actual evapotranspiration ( ETa ) rates can be used to inversely identify effective soil hydraulic parameters. ETa rates from fully developed crops during water stress periods are most suitable for this purpose. Frequent measurement on ETa rates is desired not only to precisely estimate the soil hydraulic parameters but also to reduce the undesirable correlation between different fitting parameters.

Forwards and backward simulations for seven heterogeneous soil profiles showed that for practical applications, effective soil hydraulic parameters can sufficiently describe the hydraulic behaviour for such profiles. However, if actual soil evaporation and transpiration are to be simulated separately and interpreted independently, an empirical formulation of soil evaporation is very important if the surface soil layers have deviating soil hydraulic properties. The effective soil hydraulic parameters for heterogeneous soils can be determined using information on ETa rates provided general information on soil texture is known.

Twenty three NOAA AVHRR satellite images were used to produce ETa maps of the Sirsa Irrigation Circle. The ETa rates were then used to inversely identify the soil hydraulic parameters for the distributed irrigation water management model FRAME. The inversely identified soil hydraulic parameters were in good agreement with the expected values but could not be validated due to absence of such information at the scale of model application.

Information on remotely sensed ETa rates and field observation on groundwater levels was also used to estimate actual groundwater use in the study area. Observations on groundwater heads for five years was then used to inversely identify the drainable porosity of the aquifer. Subsequently the model results were validated against observed groundwater heads for nine years and overall good agreement was obtained.

After calibration, the FRAME model was used to analyse irrigation water management at regional scale. Three alternate water management scenarios involving partial reduction in canal water supply and increased groundwater extraction were simulated. Effects of alternate water management scenarios on crop ETa and groundwater level depths were predicted. It was observed that in the study area where groundwater levels are rising reduction in canal water supply by 25 % during rainy season is unlikely to have any adverse effect on the development of soil salinity. Reduction in ETa due to decreased canal water supply can be partly compensated for by the increase in groundwater use.

Water and nutrient budgets at field and regional scale : travel times of drainage water and nutrient loads to surface water
Eertwegh, G.A.P.H. van den - \ 2002
Wageningen University. Promotor(en): R.A. Feddes; J.L. Nieber. - S.l. : S.n. - ISBN 9789058086990 - 260
drainage - stroming door macroporiën - hydraulisch geleidingsvermogen - voedingsstoffenbalans - waterbalans - modellen - nitraten - drainage - macropore flow - hydraulic conductivity - nutrient balance - nitrates - water balance - models

Keywords : water and nutrient budget, travel time of drainage water, dual-porosity concept, agricultural nutrient losses, loads to surface water, field-scale experiments, regional-scale approach.

Nitrogen and phosphorus loads to surface waters have caused eutrophication problems in the Netherlands. Currently, surface water quality standards are not met due to loads from point and diffuse sources. Linking agricultural nutrient budget surpluses to observed losses of nutrients to the surface water by drainage requires water and nutrient balances as well as a travel time distribution of drainage water. In this research the travel time of drainage water was estimated by using steady-state flow analysis as well as transient modeling i.e., using a 2D dual-porosity water flow and solute transport code . To analyze and estimate nutrient loads to the surface water, this research covered both field-scale analyses as well as a regional-scale approach .

At the Flevoland field experimental site , arable crops were grown on clay soil. The presence of a non-ripened clay layer in the soil profile appeared to be a key factor in the division of total drainage into tile drainage, drainage through a collecting and draining ditch, and drainage through the regional surface water. Tile drainage in the 1992-1994 period was between 50% and 85% of the total drainage. Nutrient losses by drainage were 55-86 kg ha -1 a -1 N and less than 0.5 kg ha -1 a -1 P and measured nutrient loads of drainage water exceeded the nutrient balance surpluses. The travel time distribution was first estimated by using a steady-state approach, and then confirmed by transient modeling, with some deviations, mainly during dry years. The travel time distribution of drainage showed that 50-60% of the local drainage water had a travel time of less than two years. Taking the travel time distribution into account, the observed N-loads of drainage water could be reasonably predicted. The P-surplus was almost fully adsorbed by the clay soil. The Hupsel-Assink field experimental site was located on grassland on a loamy sand. About 70% of total drainage was discharged by tile drains in the 1993-1994 period. N-losses by drainage were 165 kg ha -1 a -1N and the calculated P-loads were unreliable. About 50-70% of the drainage water had a travel time of less than two years. The travel time distribution was estimated by using a simple steady-state approach, and then confirmed by transient modeling. Using the travel time distribution, the observed drainage N-loads could be reasonably predicted. The P-surplus was almost fully adsorbed by the loamy sand. Both field experiments showed the relevance and importance of a thorough data analysis and of the travel time distribution of drainage water, which is needed to interpret and link agricultural practices to nutrient losses by drainage.

The Regional scale approach estimated annual water flow and solute loads to the regional surface water, taking point sources and groundwater seepage into account. Annual water, salt, nitrogen, and phosphorus budgets were calculated for the Hoge Afdeling region in the Flevopolder area (1988-1999) and the Hupsel brook basin (1985-1994). A regional-scale travel time distribution of drainage water was estimated. Annual averages of nutrient loads to the regional surface water were well predicted. Nutrient losses by drainage from agricultural land and groundwater seepage were important sources in the Hoge Afdeling region, whereas in the Hupsel brook basin, nutrient losses by drainage from agricultural land were the main source. Accurate solute load estimates of the regional surface water based on well-designed surface-water-quality monitoring programs proved beneficial.

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