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.

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Systeemstap naar minimaal energieverbruik Alstroemeria : metingen op praktijkbedrijven en een energiezuinige teeltconcept
Garcia Victoria, N. ; Zwart, Feije de; Weel, Peter van; Steenhuizen, Johan ; Groot, Marco de - \ 2017
Bleiswijk : Wageningen University & Research, BU Glastuinbouw (Rapport GTB 1372) - 66
kasgewassen - glastuinbouw - kastechniek - kassen - alstroemeria - energiebehoeften - energiebesparing - verwarming - aanvullend licht - kunstlicht - simulatiemodellen - isolatie (insulation) - evaporatie - greenhouse crops - greenhouse horticulture - greenhouse technology - greenhouses - energy requirements - energy saving - heating - supplementary light - artificial light - simulation models - insulation - evaporation
Alstroemeria cultivation in The Netherlands requires energy for heating, supplementary light and root cooling. For the program “Greenhouse as Source of Energy” we calculated to which extent the energy demand for growing this crop can be reduced with existing energy saving innovations. Some innovations were tested in practice, others were calculated by means of the greenhouse climate simulation model Kaspro. Results showed that it is possible to save up to 34% energy for heating compared to the reference situation. 40% energy can be saved on electricity for supplementary light and root cooling. However, this strategy leads to a reduced amount of PAR-light in the winter, and 4% less flowers in comparison with the reference. The greatest impact can be achieved by increasing the insulation of the greenhouse by using double screens, reducing the evaporation from the soil, improving the crop hygiene to avoid extra evaporation from crop debris and reduce pest pressure, and implementing controlled dehumidification of the greenhouse air.
Indampen van dunne mestfracties in combinatie met een luchtwasser
Hoeksma, P. ; Hol, A. ; Verheijen, R. ; Verdoes, N. - \ 2017
Wageningen : Wageningen Livestock Research (Wageningen Livestock Research rapport 1014) - 25
vloeibare meststoffen - drijfmest - evaporatie - reinigers - ammoniakemissie - varkenshouderij - liquid manures - slurries - evaporation - scrubbers - ammonia emission - pig farming
The effect of an evaporator/air-scrubber combination on the reduction of ammonia and odour was evaluated and the evaporation capacity was assessed. It was concluded that at pig farms substantial reduction (one third) of the slurry volume can cost effectively be achieved while maintaining ammonia and odour reduction effiency.
Snijbloemen telen bij hoge RV met behoud van kwaliteit : literatuuronderzoek in opdracht van Kas als Energiebron
Garcia Victoria, Nieves ; Slootweg, Casper ; Marissen, Nollie - \ 2016
Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1410) - 58
snijbloemen - glastuinbouw - kasgewassen - kassen - relatieve vochtigheid - evaporatie - vaasleven - huidmondjes - literatuuroverzichten - cut flowers - greenhouse horticulture - greenhouse crops - greenhouses - relative humidity - evaporation - vase life - stomata - literature reviews
Om CO2 voor de fotosynthese naar het blad te leiden, hebben planten huidmondjes. Via de open huidmondjes verdampt water. De plant reguleert de opening en sluiting van huidmondjes, en dus haar waterhuishouding, aan de hand van prikkels uit de omgeving (water, CO2, licht). Snijbloemen verliezen na de oogst water door verdamping wat weer aangevuld moet worden via de steel met het vaaswater. Bij goed functionerende huidmondjes is die verdamping beperkt, maar de huidmondjes van snijbloemen die geteeld zijn bij aanhoudend hoge RV zijn anatomisch en fysiologisch anders: ze zijn ongevoelig voor sluitingsprikkels, waardoor ze in de vaas sterk door blijven verdampen. Dit leidt tot een korter vaasleven omdat de wateropname door de afgesneden steel beperkend wordt. Het ontbreken van een donkerperiode tijdens de teelt leidt ook tot niet-functionele huidmondjes. Als er gedurende de ontwikkeling regelmatig een sluitings-prikkel wordt gegeven, blijven huidmondjes functioneel. Dit zou gerealiseerd kunnen worden door het hanteren van een donker-periode in combinatie met een voldoende lage RV, periodieke verlagingen van de RV tijdens de teelt, de teelttemperatuur ’s nachts verhogen (waarmee de RV daalt), of een sterke luchtbeweging (kortstondig ingezet). Groen (LED) licht aan het begin van de nachtperiode en het gebruik van schermen tegen uitstraling kunnen wellicht ook de huidmondjes functionaliteit positief beïnvloeden, maar daar is nog onvoldoende over bekend. Het Nieuwe Telen is er sterk op gericht om de huidmondjes open te houden voor maximale fotosynthese en productie door, onder andere, het handhaven van een hoge RV. Bij producten die geen last hebben van waterverlies na de oogst, zoals vruchtgroenten leidt het tot zeer goede productie en kwaliteit met weinig inzet van energie. Het Nieuwe Telen is sterk in ontwikkeling. Bij het vertalen van Het Nieuwe Telen naar bladhoudende snijbloemen dient er ruimte te worden gemaakt voor een regelmatig terugkomende trigger om de huidmondjes te laten sluiten wil het succesvol toegepast kunnen worden.
Een nieuwe en handzame lysimeter: eerste stap naar een nationaal netwerk voor de werkelijke verdamping?
Voortman, Bernard ; Witte, J.P. ; Rheenen, Hans van; Bosveld, F. ; Elbers, J.A. ; Bolt, F.J.E. van der; Heijkers, J. ; Hoogendoorn, Jan ; Bolman, A. ; Spek, T. ; Voogt, M. - \ 2016
Stromingen : vakblad voor hydrologen 22 (2016)2. - ISSN 1382-6069 - p. 49 - 63.
hydrologie - neerslag - waterbalans - grondwater - lysimeters - evaporatie - hydrology - precipitation - water balance - groundwater - evaporation
Vrijwel overal op aarde verdampt meer dan de helft van het neerslagwater, ook in Nederland. Toch wordt deze grote verliespost in ons land slechts sporadisch gemeten. Door inspanningen van kennisinstituten, bedrijven en overheid is daarom een lysimeter ontwikkeld. Metingen in 2014 en 2015 op twee locaties vertonen opvallende verschillen, maar ook grote overeenkomsten, met eddy-correlatiemetingen. Schattingen van de verdamping via satellietdata zijn hoger dan de metingen. Tijd daarom, om metingen in het veld te combineren met modellen en waarnemingen vanuit de ruimte
Telen met gestuurde vochtafvoer : komkommers in de Venlow Energy kas
Gelder, A. de - \ 2016
Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1408)
teelt onder bescherming - kasgewassen - glasgroenten - glastuinbouw - dubbele beglazing - komkommers - cucumis sativus - evaporatie - ventilatie - vochtigheid - protected cultivation - greenhouse crops - greenhouse vegetables - greenhouse horticulture - double glazing - cucumbers - evaporation - ventilation - humidity
Funded by Kas als Energiebron, Wageningen UR Greenhouse Horticulture conducted an experiment witth cucumber in the Venlow Energy greenhouse with a high-wire system. The objective was to achieve a minimal evaporation during cultivation under double glazing and a film screen. In the night the evaporation fell to 15-25 g. m-2.hour-1. This was enough to grow cucumbers without deficiency symptoms. Only in March, some degree of “bolblad” occurred, but after a few sunny days the crop well recovered. The film screen was kept closed until 2 hours after sunset and one hour before sundown closed. This provided no problems for cultivation. In the night the humidity could rise above 95% without Mycosphearella problems. For the new cultivation strategy this means if other factors such as horizontal uniformity of the climate are good that cultivation in high humidity and with minimal ventilation is possible. For the Venlow Energy greenhouse ventilation rate was 0.37 and this delivers in winter conditions a sufficient degree of natural ventilation and moisture management.
A framework for sourcing of evaporation between saturated and unsaturated zone in bare soil condition
Balugani, E. ; Lubczynski, M.W. ; Metselaar, Klaas - \ 2016
Hydrological Sciences Journal 61 (2016)11. - ISSN 0262-6667 - p. 1981 - 1995.
evaporation - ground water balance - HYDRUS - liquid and vapour flow - sourcing

Sourcing subsurface evaporation (Ess) into groundwater (Eg) and unsaturated zone (Eu) components has received little scientific attention so far, despite its importance in water management and agriculture. We propose a novel sourcing framework, with its implementation in dedicated post-processing software called SOURCE (used along with the HYDRUS1D model), to study evaporation sourcing dynamics, define quantitatively “shallow” and “deep” water table conditions and test the applicability of water table fluctuation (WTF) and “bucket” methods for estimation of Eg and Eu separately. For the “shallow” and “deep” water table we propose Eg > 0.95Ess and Eg = 0 criteria, respectively. Assessment of the WTF method allowed sourcing of very small fluxes otherwise neglected by standard hydrological methods. Sourcing with SOURCE software was more accurate than the standard “bucket” method mainly because of greater flexibility in spatio-temporal discretization. This study emphasized the dry condition relevance of groundwater evaporation which should be analysed by applying coupled flow of heat, vapour and liquid water.

Deep frying : from mechanisms to product quality
Koerten, K.N. van - \ 2016
University. Promotor(en): Maarten Schutyser, co-promotor(en): Remko Boom. - Wageningen : Wageningen University - ISBN 9789462576476 - 119 p.
deep fat frying - quality - chips (french fries) - evaporation - crusts - moisture meters - fried foods - crisps - frituren - kwaliteit - patates frites - evaporatie - korsten - vochtmeters - gebakken voedsel - aardappelchips

Deep frying is one of the most used methods in the food processing industry. Though practically any food can be fried, French fries are probably the most well-known deep fried products. The popularity of French fries stems from their unique taste and texture, a crispy outside with a mealy soft interior, but also because of the ease and speed of preparation. However, despite being a practical and easy method, the fundamental phenomena that occur during frying are very complex. This thesis aimed at gaining a deeper understanding of the frying of French fries. This was done at the product level, with regards to heat transfer, moisture loss, oil uptake and crust formation, and at the process level, which encompasses the oil movement in a frying unit and the consequent oil-fry interactions.

Firstly a numerical model was developed to describe the water evaporation during frying (Chapter 2). Though various models exist for describing moisture loss, they all use constant values for the heat transfer coefficient. However, the heat transfer coefficient actually varies greatly due to the varying degrees of turbulence, induced by the vapour bubbles escaping from the fry surface. Therefore, the model in this thesis incorporated an evaporation rate dependent heat transfer coefficient. Other than the varying heat transfer coefficient, the model was heat transfer dependent, with a sharp moving evaporation boundary and Darcy flow describing the flow of water vapour through the crust. The model was successfully validated against experimental results for moisture loss and temperature profiles in the fry.

For oil uptake during frying, a pore inactivation model from membrane technology was adopted (Chapter 3). In membranes, pores will inactivate when the transmembrane pressure becomes too low. In fries, this can be translated as pores in the crust inactivating when the evaporation rate becomes too low. As pores stop expelling water vapour, oil can migrate into the fry. The model also took into account the lengthening of the pores with increasing crust thickness, allowing for more oil uptake in inactivated pores. The model fitted well with experimental data for oil uptake during frying. Also, the pore inactivation model better described oil uptake during the initial stages of frying, where the evaporation rate is still relatively high, compared to the linear relation between oil uptake and moisture content, which is usually assumed in literature.

Both the influences of frying temperature and moisture content on crust structure and consequent textural properties were studied (Chapter 4). The crust structure was visualized and quantified using X-ray tomography (XRT), which uses multiple 2D X-ray pictures of a rotated sample to reconstruct a 3D density map. Textural properties, like hardness and crispness, were quantified using force deformation curves from a texture analyser. Moisture loss was shown to greatly increase porosity and pore size in fries. More crispy behaviour was also shown for higher moisture loss, though not significantly at moisture contents close to the initial moisture content. Though increased frying temperatures also showed an increased porosity and pore size, there was no significantly observed increase in crispness. This is most likely because the texture analysis was not sensitive enough to discern any increased crispness for porosities below a certain degree. Strikingly, for frying temperature around 195 °C, a decrease in crispness was observed. These samples visually also showed more plastic behavior. The most likely cause for this is degradation of sucrose, which happens around 186 °C, and consequent caramelization of glucose, thus increasing the glass transition temperature.

At the process level, oil flow and fry quality distribution were investigated using a pilot scale cross-flow fryer (Chapter 5). Oil circulation velocities were varied to observe the initial fluidization behavior of the fry bed through an observation window. This fluidization behavior was well described by the Ergun equation, modified for non-spherical particles. The distribution in moisture content of the fries was used as an indicator for quality distribution. Though increased oil circulation initially increased the homogeneity of the moisture content, upon fluidization the homogeneity actually decreased. Image analysis of fries before and after frying showed local packing of fries around their fluidization point. This was due to the non-spherical shape of the fries, making them more sensitive to channelling.

The results obtained in this thesis were finally discussed, together with the possibility to also model the process scale of the frying process (Chapter 6). The possibility of modelling the oil flow through a packed bed of fries, and the free-convective heat transfer during frying, using a CFD software package (STARCCM+) was shown. Additionally, the possibility of linking oil flows computed using CFD to the general models developed in this thesis was discussed. Modelling the momentum transfer of the expelled vapour bubbles to the oil, but also the movement of the fries themselves is still a faraway goal. However, a multiphase model that can describe both the entire frying setup as the consequent individual fry parameters would be invaluable.

Hoeveel water verdampt de stad?
Jacobs, C.M.J. ; Elbers, J.A. ; Moors, E.J. ; Hove, L.W.A. van - \ 2015
Water Matters : Kenniskatern voor Waterprofessionals - Dutch edition (2015)oktober. - p. 34 - 37.
evaporatie - waterbeheer - stedelijke gebieden - stedelijke samenleving - waterbehoefte - klimaatverandering - zoet water - evaporation - water management - urban areas - urban society - water requirements - climatic change - fresh water
Hoeveel water verliest een stad door verdamping? Wat betekent dat? En is dat proces van verdamping te beïnvloeden? Onderzoek van Alterra Wageningen UR levert inzichten op die voor de steden steeds belangrijker zullen worden.
Beheerst vocht afvoeren zorg voor energiebesparing : energiebalans toont aan waar de verliezen zitten
Velden, P. van; Raaphorst, M.G.M. ; Zwart, H.F. de - \ 2015
Onder Glas 12 (2015)6/7. - p. 40 - 41.
glastuinbouw - kastechniek - kassen - ontvochtiging - energiebesparing - ventilatie - evaporatie - energiebalans - schermen - modellen - greenhouse horticulture - greenhouse technology - greenhouses - dehumidification - energy saving - ventilation - evaporation - energy balance - blinds - models
Met een model van de energiebalans van een kas lukt het om in één oogopslag de kwetsbare kanten van energieverliezen zichtbaar te maken. Verdamping gebruikt kostbare energie en die vervliegt via de luchtramen als een teler de RV wil verlagen. Dat kan anders, vinden onderzoekers van Wageningen UR Glastuinbouw. Hoe gelijkmatiger het kasklimaat, des te hoger mag de relatieve luchtvochtigheid oplopen.
Selecting crop models for decision making in wheat insurance
Castaneda Vera, A. ; Leffelaar, P.A. ; Alvaro-Fuentes, J. ; Cantero-Martinez, C. ; Minguez, M.I. - \ 2015
European Journal of Agronomy 68 (2015). - ISSN 1161-0301 - p. 97 - 116.
use efficiency - management-practices - farming systems - field-capacity - soil - yield - evaporation - photosynthesis - transpiration - irrigation
In crop insurance, the accuracy with which the insurer quantifies the actual risk is highly dependent on the availability on actual yield data. Crop models might be valuable tools to generate data on expected yields for risk assessment when no historical records are available. However, selecting a crop model for a specific objective, location and implementation scale is a difficult task. A look inside the different crop and soil modules to understand how outputs are obtained might facilitate model choice. The objectives of this paper were (i) to assess the usefulness of crop models to be used within a crop insurance analysis and design and (ii) to select the most suitable crop model for drought risk assessment in semi-arid regions in Spain. For that purpose first, a pre-selection of crop models simulating wheat yield under rainfed growing conditions at the field scale was made, and second, four selected models (Aquacrop, CERES-Wheat, CropSyst and WOFOST) were compared in terms of modelling approaches, process descriptions and model outputs. Outputs of the four models for the simulation of winter wheat growth are comparable when water is not limiting, but differences are larger when simulating yields under rainfed conditions. These differences in rainfed yields are mainly related to the dissimilar simulated soil water availability and the assumed linkages with dry matter formation. We concluded that for the simulation of winter wheat growth at field scale in such semi-arid conditions, CERES-Wheat and CropSyst are preferred. WOFOST is a satisfactory compromise between data availability and complexity when detail data on soil is limited. Aquacrop integrates physiological processes in some representative parameters, thus diminishing the number of input parameters, what is seen as an advantage when observed data is scarce. However, the high sensitivity of this model to low water availability limits its use in the region considered. Contrary to the use of ensembles of crop models, we endorse that efforts be concentrated on selecting or rebuilding a model that includes approaches that better describe the agronomic conditions of the regions in which they will be applied. The use of such complex methodologies as crop models is associated with numerous sources of uncertainty, although these models are the best tools available to get insight in these complex agronomic systems.
Workshop gewasgezondheid en vruchtkwaliteit bij vochtig telen : kennisuitwisseling teeltadviseurs
Gelder, Arie de - \ 2015
horticulture - greenhouse horticulture - cucumis - rosa - crop quality - workshops (programs) - moisture content - mycosphaerella - radiation - evaporation - temperature - lighting - production
Reconciling spatial and temporal soi moisture effects on aftrnoon rainfall
Guillod, B.P. ; Orlowsky, B. ; Miralles, D.G. ; Teuling, A.J. ; Seneviratne, S.I. - \ 2015
Nature Communications 6 (2015). - ISSN 2041-1723
energy system ceres - stratiform precipitation - atmospheric controls - surface irradiances - land - evaporation - scale - feedback - evapotranspiration - variability
Soil moisture impacts on precipitation have been strongly debated. Recent observational evidence of afternoon rain falling preferentially over land parcels that are drier than the surrounding areas (negative spatial effect), contrasts with previous reports of a predominant positive temporal effect. However, whether spatial effects relating to soil moisture heterogeneity translate into similar temporal effects remains unknown. Here we show that afternoon precipitation events tend to occur during wet and heterogeneous soil moisture conditions, while being located over comparatively drier patches. Using remote-sensing data and a common analysis framework, spatial and temporal correlations with opposite signs are shown to coexist within the same region and data set. Positive temporal coupling might enhance precipitation persistence, while negative spatial coupling tends to regionally homogenize land surface conditions. Although the apparent positive temporal coupling does not necessarily imply a causal relationship, these results reconcile the notions of moisture recycling with local, spatially negative feedbacks.
Assessment of evaporative water loss from Dutch cities
Jacobs, C.M.J. ; Elbers, J.A. ; Brolsma, R. ; Hartogensis, O.K. ; Moors, E.J. ; Rodríguez-CarreteroMárquez, M.T. ; Hove, B. van - \ 2015
Building and Environment 83 (2015). - ISSN 0360-1323 - p. 27 - 38.
klimaatverandering - temperatuur - stedelijke gebieden - evaporatie - waterbudget - rotterdam - veluwe - climatic change - temperature - urban areas - evaporation - water budget - urban heat-island - energy-balance - large-aperture - evapotranspiration - exchange - surface - scintillometers - requirements - environments - manchester
Reliable estimates of evaporative water loss are required to assess the urban water budget in support of division of water resources among various needs, including heat mitigation measures in cities relying on evaporative cooling. We report on urban evaporative water loss from Arnhem and Rotterdam in the Netherlands, using eddy covariance, scintillometer and sapflow observations. Evaporation is assessed at daily to seasonal and annual timescale. For the summer half-year (April–September), observations from Arnhem and Rotterdam are consistent regarding magnitude and variability of evaporation that typically varies between 0.5 and 1.0 mm of evaporation per day. The mean daily evaporative cooling rate was 20–25 Wm-2, 11–14% of the average incoming solar radiation. Evaporation by trees related to sapflow was found to be a small term on the water budget at the city or neighbourhood scale. However, locally the contribution may be significant, given observed maxima of daily sap flows up to 170 l per tree. In Arnhem, evaporation is strongly linked with precipitation, possibly owing to building style. During the summer season, 60% of the precipitation evaporated again. In Rotterdam, the link between evaporation and precipitation is much weaker. An analysis of meteorological observations shows that estimation of urban evaporation from routine weather data using the concept of reference evaporation would be a particularly challenging task. City-scale evaporation may not scale with reference evaporation and the urban fabric results in strong microweather variability. Observations like the ones presented here can be used to evaluate and improve methods for routine urban evaporation estimates.
Influence of the relative humidity on the morphology of inkjet printed spots of IgG on a non-porous substrate.
Mujawar, L.H. ; Kuerten, J.G.M. ; Siregar, D.P. ; Amerongen, A. van; Norde, W. - \ 2014
RSC Advances : An international journal to further the chemical sciences 4 (2014)37. - ISSN 2046-2069 - p. 19380 - 19388.
experimental-verification - protein microarrays - dna microarrays - contact-angle - evaporation - surfaces - drops - performance - fabrication - adsorption
During the drying of inkjet printed droplets, the solute particles (IgG-Alexa-635 molecules) in the drop may distribute unevenly on the substrate, resulting in a “coffee-stain” spot morphology. In our study, we investigated the influence of the relative humidity on the distribution of inkjet printed fluorophore labeled IgG molecules on a polystyrene substrate. A theoretical model for an evaporating droplet was developed in order to predict the changes in the spot diameter, height and volume of a drying droplet. An experiment was performed where a sessile droplet was monitored using a CCD camera installed on a goniometer and good agreement was found between the experimental results and simulation data. We also compared the predicted morphology for an inkjet-printed microarray spot with the experimental results where IgG molecules were printed for various relative humidities. The spot morphology of the dried spots was analyzed by a confocal laser microscopy. At a lower relative humidity (i.e.,
Mega-heatwave temperatures due to combined soil desiccation and atmospheric heat accumulation
Miralles, D. ; Teuling, A.J. ; Heerwaarden, C.C. van; Vilà-Guerau de Arellano, J. - \ 2014
Nature geoscience 7 (2014). - ISSN 1752-0894 - p. 345 - 349.
boundary-layer - land-surface - summer - europe - evaporation - extremes - moisture - impact - wave
The recent European mega-heatwaves of 2003 and 2010 broke temperature records across Europe1, 2, 3, 4, 5. Although events of this magnitude were unprecedented from a historical perspective, they are expected to become common by the end of the century6, 7. However, our understanding of extreme heatwave events is limited and their representation in climate models remains imperfect8. Here we investigate the physical processes underlying recent mega-heatwaves using satellite and balloon measurements of land and atmospheric conditions from the summers of 2003 in France and 2010 in Russia, in combination with a soil–water–atmosphere model. We find that, in both events, persistent atmospheric pressure patterns induced land–atmosphere feedbacks that led to extreme temperatures. During daytime, heat was supplied by large-scale horizontal advection, warming of an increasingly desiccated land surface and enhanced entrainment of warm air into the atmospheric boundary layer. Overnight, the heat generated during the day was preserved in an anomalous kilometres-deep atmospheric layer located several hundred metres above the surface, available to re-enter the atmospheric boundary layer during the next diurnal cycle. This resulted in a progressive accumulation of heat over several days, which enhanced soil desiccation and led to further escalation in air temperatures. Our findings suggest that the extreme temperatures in mega-heatwaves can be explained by the combined multi-day memory of the land surface and the atmospheric boundary layer
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 - 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¿
Land atmosphere feedbacks and their role in the water resources of the Ganges basin
Harding, R.J. ; Blyth, E.M. ; Tuinenburg, O.A. ; Wiltshire, A. - \ 2013
Science of the Total Environment 468-469 (2013). - ISSN 0048-9697 - p. S85 - S92.
asian summer monsoon - mixed-layer model - soil-moisture - climate-change - variability - evaporation - irrigation - precipitation - regions - scheme
The northern Indian subcontinent has frequently been identified as a hotspot for land atmosphere interactions. It is also a region with the highest concentration of irrigated land and highest (and increasing) population density in the world. The available water in the region with which to grow food depends on the Asian monsoon, groundwater and melt from Himalayan snows. Any changes or disruptions to these sources of water could threaten the food supply. It is therefore essential to understand how the land surface, and in particular irrigated land, interacts with the atmosphere. It is anticipated that the interactions will occur on many scales. To an extent the magnitude and form of these will depend on the depth of the atmosphere which is affected. Thus at the local, or micro, scale it is the surface layer (some 10s m deep) which is cooled and moistened by the evaporation of irrigated water, at the meso-scale the Planetary boundary layer (up to 1 or 2 km) will be modified with possible atmospheric moistening, increased cloud and rain formation and at very large scales the whole dynamics of the south Asian Monsoon will be affected. This illustrates a strong interaction between the Asian monsoon and the regional topography. Of considerable significance is the finding in this paper that up to 60% of the evaporation from irrigated areas in the summer months is ultimately recycled to Himalayan rainfall and so feedbacks to river flows in the Ganges. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.
Benchmark products for land evapotranspiration: LandFlux-EVAL multi-data set synthesis
Mueller, B. ; Hirschi, M. ; Jimenez, C. ; Ciais, P. ; Dirmeyer, P.A. ; Dolman, A.J. ; Fisher, J.B. ; Jung, M. ; Ludwig, F. ; Maignan, F. - \ 2013
Hydrology and Earth System Sciences 17 (2013). - ISSN 1027-5606 - p. 3707 - 3720.
reanalysis data - soil-moisture - global-scale - surface - climate - trends - model - 20th-century - variability - evaporation
Land evapotranspiration (ET) estimates are available from several global datasets. Here, monthly global land ET synthesis products, merged from these individual datasets over the time periods 1989–1995 (7 yr) and 1989–2005 (17 yr), are presented. The 5 merged synthesis products over the shorter period are based on a total of 40 distinct datasets while those over the longer period are based on a total of 14 datasets. In the individual datasets, ET is derived from satellite and/or in-situ observations (diagnostic datasets) or calculated via land-surface models (LSMs) driven with observationsbased forcing and atmospheric reanalyses. Statistics for four merged synthesis prod10 ucts are provided, one including all datasets and three including only datasets from one category each (diagnostic, LSMs, and reanalyses). The multi-annual variations of ET in the merged synthesis products display realistic responses. They are also consistent with previous findings of a global increase in ET between 1989 and 1997 (1.15mmyr-2 in our merged product) followed by a decrease in this trend (-1.40mmyr-2), although 15 these trends are relatively small compared to the uncertainty of absolute ET values. The global mean ET from the merged synthesis products (based on all datasets) is 1.35mm per day for both the 1989–1995 and 1989–2005 products, which is relatively low compared to previously published estimates. We estimate global runoff (precipitation minus ET) to 34 406 km3 per year for a total land area of 130 922 km2. Precipitation, 20 being an important driving factor and input to most simulated ET datasets, presents uncertainties between single datasets as large as those in the ET estimates. In order to reduce uncertainties in current ET products, improving the accuracy of the input variables, especially precipitation, as well as the parameterizations of ET are crucial.
Viral shedding and emission of airborne infectious bursal disease virus from a broiler room
Zhao, Y. ; Aarnink, A.J.A. ; Cambra-Lopez, M. ; Fabri, T. - \ 2013
British Poultry Science 54 (2013)1. - ISSN 0007-1668 - p. 87 - 95.
respiratory-syndrome virus - newcastle-disease - united-kingdom - pig houses - chickens - transmission - immunosuppression - temperature - persistence - evaporation
1. The significance of airborne transmission in epidemics of infectious diseases in the livestock production industry remains unclear. The study therefore investigated the shedding route (faeces vs. exhaled air) of a vaccine strain of infectious bursal disease virus (IBDV) by broilers and the emission of airborne virus. 2. The experimental room contained 526 broilers which were orally inoculated at the age of 20¿d. The airborne virus was sampled by three different bioaerosol samplers: Andersen six-stage impactor, all-glass impinger (AGI-30) and OMNI-3000. 3. Infected broilers started to shed virus in faeces on d 5 post inoculation (PI), and stopped shedding on d 12 PI. The faecal virus remained detectable for at least two d after drying under broiler room conditions. No virus was detected in the air exhaled by broilers. 4. Airborne virus was collected on d 5, 8 and 12 PI at 20¿cm above the floor, and on d 8 and 12 PI in exhausted air. The emission rates of IBDV were 4·0 log10 50% tissue culture infectious dose (TCID50)/bird/d on d 8 PI, and 4·5 log10 TCID50/bird/d on d 12 PI. 5. We concluded that broilers shed IBDV mainly through their faeces. The presence of indoor airborne virus is associated with the viral presence in faeces. The successful recovery of airborne virus in exhausted air indicates there is a potential risk of virus spreading to the ambient environment via air.
A climate robust integrated modelling framework for regional impact assessment of climate change
Janssen, G. ; Bakker, A. ; Ek, R. van; Groot, A.M.E. ; Kroes, J.G. ; Kuiper, M. ; Schipper, P.N.M. ; Walsum, P.E.V. van; Wamelink, W. ; Mol, J. - \ 2013
klimaatverandering - grondwaterstand - gewasgroeimodellen - evaporatie - grondwater - modellen - climatic change - groundwater level - crop growth models - evaporation - groundwater - models
Decision making towards climate proofing the water management of regional catchments can benefit greatly from the availability of a climate robust integrated modelling framework, capable of a consistent assessment of climate change impacts on the various interests present in the catchments. In the Netherlands, much effort has been devoted to developing state-of-the-art regional dynamic groundwater models with a very high spatial resolution (25x25 m2). Still, these models are not completely satisfactory to decision makers because the modelling concepts do not take into account feedbacks between meteorology, vegetation/ crop growth, and hydrology. This introduces uncertainties in forecasting the effects of climate change on groundwater, surface water, agricultural yields, and development of groundwater dependent terrestrial ecosystems. These uncertainties add to the uncertainties about the predictions on climate change itself. In order to create an integrated, climate robust modelling framework, we coupled existing model codes on hydrology, agriculture and nature that are currently in use at the different research institutes in the Netherlands. The modelling framework consists of the model codes MODFLOW (groundwater flow), MetaSWAP (vadose zone), WOFOST (crop growth), SMART2-SUMO2 (soil-vegetation) and NTM3 (nature valuation). MODFLOW, MetaSWAP and WOFOST are coupled online (i.e. exchange information on time step basis). Thus, changes in meteorology and CO2-concentrations affect crop growth and feedbacks between crop growth, vadose zone water movement and groundwater recharge are accounted for. The model chain WOFOST-MetaSWAP-MODFLOW generates hydrological input for the ecological prediction model combination SMART2-SUMO2-NTM3. The modelling framework was used to support the regional water management decision making process in the 267 km2 Baakse Beek-Veengoot catchment in the east of the Netherlands. Computations were performed for regionalized 30-year climate change scenarios developed by KNMI for precipitation and reference evapotranspiration according to Penman-Monteith. Special focus in the project was on the role of uncertainty. How valid is the information that is generated by this modelling framework? What are the most important uncertainties of the input data, how do they affect the results of the model chain and how can the uncertainties of the data, results, and model concepts be quantified and communicated? Besides these technical issues, an important part of the study was devoted to the perception of stakeholders. Stakeholder analysis and additional working sessions yielded insight into how the models, their results and the uncertainties are perceived, how the modelling framework and results connect to the stakeholders’ information demands and what kind of additional information is needed for adequate support on decision making.
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