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Earthlings like to measure everything (especially now that we are undergoing the era of big-data revolution) maybe because it is such a nice hobby... although a more serious school of thought believes that when measuring our environment we get to understand physics and ourselves. This thesis explores the uncertainties in rainfall measurements from state-of-the-art technologies like commercial microwave links (CML) and meteorological satellites. Rainfall has been measured by rain gauges since quite some time ago; and by weather radars since the end of WWII. Here we evaluate the performance of gridded-rainfall products for the land surface of the Netherlands. These gridded-rainfall products are CML-rainfall maps produced by the Royal Netherlands Meteorology Institute (KNMI), and the IMERG product developed by Global Precipitation Measurement mission (GPM). Overall, this thesis shows that CML-rainfall products are very reliable sources with regards to rainfall estimates for the land surface of the Netherlands... even better than the satellite products for rainfall estimation. We are also confident in the promising potential these technologies hold for places around the world where conventional technologies like gauges or radars are not scarce or not affordable.

De meest fundamentele en daarmee belangrijkste activiteit van hydrologen is het opstellen van waterbalansen. Immers, waterbalansen vormen het hart van elke watersysteemanalyse, inclusief het ontwikkelen, kalibreren en valideren van modellen. Naast de neerslag en verdamping vormen de aan- en afvoer van oppervlaktewater de belangrijkste componenten van de Nederlandse waterbalans. Die worden indirect afgeleid uit metingen bij klepstuwen, afsluiters, pompgemalen e.d. In dit artikel gaan wij in op de vraag hoe accuraat met zulke meetmethodes de debieten aan- en afvoeren in de praktijk kunnen worden geschat en hoe dit verbeterd kan worden. Wij concluderen dat de onzekerheden groot zijn en dat er veel te verbeteren is over het gehele traject: het uitvoeren van de metingen, het ijken van de formules van de meetopstellingen met alternatieve meetmethodes, de opslag en verwerking van de ruwe meetdata naar debieten en het kwantificeren van onzekerheden daarin.

We present an estimate of net ecosystem exchange (NEE) of CO2 in Europe for the years 2001-2007. It is derived with a data assimilation that uses a large set of atmospheric CO2 mole fraction observations (∼70 000) to guide relatively simple descriptions of terrestrial and oceanic net exchange, while fossil fuel and fire emissions are prescribed. Weekly terrestrial sources and sinks are optimized (i.e., a flux inversion) for a set of 18 large ecosystems across Europe in which prescribed climate, weather, and surface characteristics introduce finer scale gradients. We find that the terrestrial biosphere in Europe absorbed a net average of -165 Tg C yr-1 over the period considered. This uptake is predominantly in non-EU countries, and is found in the northern coniferous (-94 Tg C yr-1) and mixed forests (-30 Tg C yr-1) as well as the forest/field complexes of eastern Europe (-85 Tg C yr-1). An optimistic uncertainty estimate derived using three biosphere models suggests the uptake to be in a range of -122 to -258 Tg C yr-1, while a more conservative estimate derived from the a-posteriori covariance estimates is -165±437 Tg C yr-1. Note, however, that uncertainties are hard to estimate given the nature of the system and are likely to be significantly larger than this. Interannual variability in NEE includes a reduction in uptake due to the 2003 drought followed by 3 years of more than average uptake. The largest anomaly of NEE occurred in 2005 concurrent with increased seasonal cycles of observed CO2. We speculate these changes to result from the strong negative phase of the North Atlantic Oscillation in 2005 that lead to favorable summer growth conditions, and altered horizontal and vertical mixing in the atmosphere. All our results are available through http://www.carbontracker.eu. © 2009 Blackwell Publishing Ltd.

Surface emissions of CO2 from fossil fuel combustion (¿FFCO2) are estimated for the Netherlands for the period of May 2006–June 2009 using ambient atmospheric observations taken at station Lutjewad in the Netherlands (6°21'E, 53°24'N, 1 m. a.s.l.). Measurements of ¿14C on 2-weekly integrations of CO2 and CO mixing ratios are combined to construct a quasi-continuous proxy record (FFCO2*) from which surface fluxes (¿FFCO2*) are determined using the 222Rn flux method. The trajectories of the air masses are analysed to determine emissions, which are representative for the Netherlands. We compared our observationally based estimates to the national inventories and we evaluated our methodology using the regional atmospheric transport model REMO. Based on 3 yr of observations we find annual mean ¿FFCO2* emissions of (4.7 ± 1.6) kt km-2 a-1 which is in very good agreement with the Dutch inventories of (4.5 ± 0.2) kt km-2 a-1 (average of 2006–2008).

The most widely used method to estimate the rumen degradation of dietary components in feedstuffs is the in situ or in sacco method. This method is based on rumen incubation of substrate (feed) in nylon or dacron bags followed by rinsing and analysis of the residue. Small pores in the bag allow microbes to enter the bag whilst a variable portion of the feed is retained in the bag. The results are used to estimate the ruminal effective degradation (ED) that is used in several protein evaluation systems. The weaknesses of the in situ method are its low precision, the lack of standardization, and its inaccuracy. The accuracy can be divided in a bias with respect to the in situ method itself, and the difference between the in situ and in vivo degradation. The bias of the in situ method itself is related to several assumptions regarding the size and degradation rate of the washable fraction, secondary particle loss, and microbial contamination. The aim of this thesis was to examine possibilities to reduce this bias by modification of the in situ methodology. The bias related to the assumptions regarding the washout fraction was successfully reduced by developing and using a modified rinsing method that involves less vigorously shaking conditions and a solvent which mimics the rumen pH and osmolality. This modified rinsing method markedly reduced the soluble (S) fraction of N, especially for legume seeds, and the non-soluble washout (W-S) fraction, especially for starch, compared to the conventional method. Consequently, the estimation of the ED became less dependent on the assumptions regarding the degradation of the S and W-S fraction. In vitro results did not support the assumption of a much faster degradation of the W-S fraction of starch than that of the non-washout fraction of starch. The modified rinsing method also allowed measuring the in situ degradation of products that contain mainly small particles such as wheat yeast concentrates. The bias related to the breakdown of particles was also successfully reduced by development and application of a combination of the modified rinsing method and an in vitro method that simulates particulate matter loss during incubation. This in vitro method was based on in situ results obtained with an inert marker (i.e., silica gel) which showed that particulate matter loss during incubation was moderate and limited to particles smaller than approximately 40 μm. Correction for these losses decreased the estimated ED of feed ingredients used. This study also showed that the fractional degradation rate of starch in grains was strongly affected by the process of secondary particulate loss when using the conventional method, and applying the modified rinsing method markedly reduced the error due to secondary particulate loss. In comparison to the conventional method, the modified method resulted in an increase of the bias related to microbial contamination of the residues. The ratio between diaminopimelic acid (DAPA), a marker for bacterial protein, and N in the residues was higher when using the modified method than that in the conventional method. The results obtained for the modified method also indicated lysis of bacterial cells during rinsing. This bias led to a lower ED when using the modified method with the impact greatly depending on the degree of lysis of bacterial cells. In summary, the modified method increased the non-washout fraction of N and starch of various feed ingredients, which offers the possibility to use it for a larger range of feed ingredients, and reduced the bias related to assumptions on the washout fraction and the breakdown of particles compared to the conventional method. On the other hand, the modified method increased the bias related to microbial contamination and enlarged the difference between the in situ and in vivo degradation.

Assessment of leaching of plant protection products to groundwater is an important aspect of the environmental risk assessment of these substances. Analysis of available Dutch groundwater monitoring data for these substances triggered a critical review of the current Dutch leaching assessment. As a result, proposals were developed for improving this assessment. These include: (i) a procedure for correcting systematic errors in measured sorption coefficients, (ii) a preliminary procedure for a quality check of Freundlich exponents, (iii) a flow chart for obtaining parameters describing the relationship between the organic-matter/water distribution coefficient, Kom, and the pH for weak acids, (iv) a procedure for obtaining a Kom endpoint from a population of Kom values including lower and upper limits, (v) a procedure for estimating the total amount of substance in soil from a concentration profile (needed for assessment of degradation half-lives from field experiments). This report is an update of the proposals reported in 2011 by the same authors based on testing the feasibility of the proposals to a few dossiers

Assessment of leaching of plant protection products to groundwater is an important aspect of the environmental risk assessment of these substances. Analysis of available Dutch groundwater monitoring data for these substances triggered a critical review of the current Dutch leaching assessment. As a result, proposals were developed for improving this assessment. These include: (i) a procedure for correcting systematic errors in measured sorption coefficients, (ii) a preliminary procedure for a quality check of Freundlich exponents, (iii) a flow chart for obtaining parameters describing the relationship between the organic-matter/water distribution coefficient, Kom, and the pH for weak acids, (iv) a procedure for obtaining a Kom endpoint from a population of Kom values including lower and upper limits, (v) a procedure for estimating the total amount of substance in soil from a concentration profile (needed for assessment of degradation half-lives from field experiments). This report is an update of the proposals reported in 2011 by the same authors based on testing the feasibility of the proposals to a few dossiers

The most widely used method to estimate the rumen degradation of dietary components in feedstuffs is the in situ or in sacco method. This method is based on rumen incubation of substrate (feed) in nylon or dacron bags followed by rinsing and analysis of the residue. Small pores in the bag allow microbes to enter the bag whilst a variable portion of the feed is retained in the bag. The results are used to estimate the ruminal effective degradation (ED) that is used in several protein evaluation systems. The weaknesses of the in situ method are its low precision, the lack of standardization, and its inaccuracy. The accuracy can be divided in a bias with respect to the in situ method itself, and the difference between the in situ and in vivo degradation. The bias of the in situ method itself is related to several assumptions regarding the size and degradation rate of the washable fraction, secondary particle loss, and microbial contamination. The aim of this thesis was to examine possibilities to reduce this bias by modification of the in situ methodology. The bias related to the assumptions regarding the washout fraction was successfully reduced by developing and using a modified rinsing method that involves less vigorously shaking conditions and a solvent which mimics the rumen pH and osmolality. This modified rinsing method markedly reduced the soluble (S) fraction of N, especially for legume seeds, and the non-soluble washout (W-S) fraction, especially for starch, compared to the conventional method. Consequently, the estimation of the ED became less dependent on the assumptions regarding the degradation of the S and W-S fraction. In vitro results did not support the assumption of a much faster degradation of the W-S fraction of starch than that of the non-washout fraction of starch. The modified rinsing method also allowed measuring the in situ degradation of products that contain mainly small particles such as wheat yeast concentrates. The bias related to the breakdown of particles was also successfully reduced by development and application of a combination of the modified rinsing method and an in vitro method that simulates particulate matter loss during incubation. This in vitro method was based on in situ results obtained with an inert marker (i.e., silica gel) which showed that particulate matter loss during incubation was moderate and limited to particles smaller than approximately 40 μm. Correction for these losses decreased the estimated ED of feed ingredients used. This study also showed that the fractional degradation rate of starch in grains was strongly affected by the process of secondary particulate loss when using the conventional method, and applying the modified rinsing method markedly reduced the error due to secondary particulate loss. In comparison to the conventional method, the modified method resulted in an increase of the bias related to microbial contamination of the residues. The ratio between diaminopimelic acid (DAPA), a marker for bacterial protein, and N in the residues was higher when using the modified method than that in the conventional method. The results obtained for the modified method also indicated lysis of bacterial cells during rinsing. This bias led to a lower ED when using the modified method with the impact greatly depending on the degree of lysis of bacterial cells. In summary, the modified method increased the non-washout fraction of N and starch of various feed ingredients, which offers the possibility to use it for a larger range of feed ingredients, and reduced the bias related to assumptions on the washout fraction and the breakdown of particles compared to the conventional method. On the other hand, the modified method increased the bias related to microbial contamination and enlarged the difference between the in situ and in vivo degradation.

A simple method was developed to estimate the fraction radiation intercepted by small eastern white cedar plants ( Thuja occidentalis 'Brabant'). The method, which describes the crop canopy as rows of cuboids, was compared with methods used for estimating radiation interception by crops with homogeneous canopies and crops grown in rows. The extinction coefficient k was determined at different plant arrangements and an average k-value of 0.48 ± 0.03 (R%sup2; = 0.89) was used in the calculations. Effects of changing plant characteristics and inter- and intra-row plant distances were explored. The fraction radiation intercepted that was estimated with the method for rows of cuboids was up to 20% and for row crops up to 8% lower than estimated with the method for homogeneous canopies at low plant densities and a LAI of 1. The fraction radiation intercepted by small plants of Thuja occidentalis 'Brabant' was best estimated by the simple method described in this paper

Expertschattingen worden gebruikt om opvattingen van experts te verzamelen over onderwerpen waarover nog weinig of geen kennis beschikbaar is. Ze kunnen ook worden ingezet om consensus over controversiële kennis te bereiken. Softwarepakketten kunnen hierbij belangrijke ondersteuning bieden, maar veel onderzoekers zijn daar niet goed van op de hoogte. Het RIVM heeft daarom een overzicht gemaakt van de verschillende mogelijkheden. Voor de inventarisatie is wetenschappelijke literatuur geraadpleegd, aangevuld met bronnen op internet. Dit is gefinancierd vanuit het strategische onderzoeksprogramma (SOR) van het instituut. Er blijken pakketten te bestaan die ondersteunen bij: 1) het samenwerken van experts en het bereiken van consensus over onderwerpen 2) de karakterisering van onzekerheden; 3) de selectie van experts; 4) het ontwerp en de uitvoering van het schattingsproces zelf en; 5) het bijeen brengen en rapporteren van de uitkomsten. Bij het ontwerpen en uitvoeren van het schattingsproces kan software helpen om de conceptuele modellen te ontwikkelen en te analyseren. Daarnaast kunnen ze assisteren bij de beoordeling van scenario's, en bij het schatten van modelparameters. Voor de karakterisering van onzekerheden is slechts één type software beschikbaar, namelijk de software die door het Planbureau voor de Leefomgeving. De ondersteunende software blijkt momenteel vaak nog niet uitgerust om expertschattingen via internet of e-mail te laten verlopen, in plaats van door een groep experts op locatie bijeen te brengen. Omdat het huidige en toekomstige gebruik van expertschattingen op het RIVM onbekend is, kan er niet geadviseerd worden over het gebruik van software in deze specifieke situaties.

IMARES voert samen met Deltares en een consortium van 4 partners monitoring uit binnen het project ‘PMR monitoring natuurcompensatie Voordelta’ in opdracht van RWS-WVL. Doel van het project is in kaart te brengen of de compensatiemaatregelen in de Voordelta, als compensatiegebied aangewezen voor de aanleg van de tweede Maasvlakte, daadwerkelijk een (positief) effect hebben op onder andere de bodemfauna. Onderdeel van de compensatiemaatregelen zijn verscherpte regelgeving voor de visserij en gedeeltelijke sluiting voor de visserij.

IMARES voert samen met Deltares en een consortium van 4 partners monitoring uit binnen het project ‘PMR monitoring natuurcompensatie Voordelta’ in opdracht van RWS-WVL. Doel van het project is in kaart te brengen of de compensatiemaatregelen in de Voordelta, als compensatiegebied aangewezen voor de aanleg van de tweede Maasvlakte, daadwerkelijk een (positief) effect hebben op onder andere de bodemfauna. Onderdeel van de compensatiemaatregelen zijn verscherpte regelgeving voor de visserij en gedeeltelijke sluiting voor de visserij.

In an osmotic tensiometer, the hydrostatic pressure of a confined polymer solution is measured to infer the soil water potential. Essential in the operation is the osmotic potential of the polymer solution. Because the osmotic potential depends on the temperature, a significant and undesired pressure lag may develop when the osmotic tensiometer is used under conditions of varying temperature. To understand and eliminate the pressure lag, a dynamic transport model was derived that describes the time response of the osmotic tensiometer while assuming complete temperature equilibration and a resistance to water transfer that is fully located within the filter. Essential elements of the model are the filter conductance and the sensitivity of the pressure transducer, for which submodels are set up. The transport model is validated with measurements on an osmotic tensiometer that uses an inorganic membrane as filter. The experiments were done for instrument-limited conditions by placing the osmotic tensiometer in free water. For these conditions, the model describes measurements with reasonable accuracy. The new transport model clarifies the behavior of the osmotic tensiometer for changing temperatures and can be used to design an osmotic tensiometer with a lower pressure lag.

Hoe kan met een zo klein mogelijke vangstinspanning 95% zekerheid worden verkregen over de aan- of afwezigheid van een soort in een gebied. Uitleg over de toepassing van de IBN-methode bij het vaststellen van de soortensamenstelling d.m.v. vallenonderzoek in verschillende vegetatietypes van De Wieden en de Weerribben (VZZ-onderzoek 1997)

Gegevens betreffende het ondernemerschap op Nederlandse akkerbouwbedrijven zijn in 2 benaderingsmethodes verwerkt, welke onderling op voorspellende nauwkeurigheid en op prijs-elasticiteit zijn vergeleken

Exposure modeling of engineered nanomaterials requires input parameters such as sedimentation rates and heteroaggregation rates. Here, we estimate these rates using quiescent settling experiments under environmentally relevant conditions. We investigated 4 different nanomaterials (C60, CeO2, SiO2-Ag and PVP-Ag) in 6 different water types ranging from a small stream to seawater. In the presence of natural colloids, sedimentation rates ranged from 0.0001 m d(-1) for SiO2-Ag to 0.14 m d(-1) for C60. The apparent rates of heteroaggregation between nanomaterials and natural colloids were estimated using a novel method that separates heteroaggregation from homoaggregation using a simplified Smoluchowski-based aggregation-settling equation applied to data from unfiltered and filtered waters. The heteroaggregation rates ranged between 0.007 and 0.6 L mg(-1) day(-1), with the highest values observed in seawater. We argue that such system specific parameters are key to the development of dedicated water quality models for ENMs.

Chapter 1. This thesis presents studies on the variability of precipitation in the Netherlands from datasets collected by radars, rain gauges and disdrometers. Accurate rainfall estimates are highly relevant in hydrology, meteorology and climatology as precipitation has a large impact on society. Precipitation has been studied extensively in the past, although it is impossible to describe all processes and behavior involved. This thesis attempts to add to the knowledge on precipitation. In the first chapter a short overview of rainfall variability at different scales is presented together with the most common instruments for measuring precipitation. Chapter 2. The spatial variability of daily rainfall accumulations is studied. Ninety-day averaged semi-variograms are created based on a 30-year data set gathered by automatic stations operated by the Royal Netherlands Meteorological Institute (KNMI). This is complemented by a one-year dataset of 10 gauges within a 5 km radius around CESAR (Cabauw Experimental Site for Atmospheric Research) in the center of the Netherlands. It is shown that it is possible to derive an average semi-variogram that describes the climatology of daily precipitation for each day of the year. Chapter 3. The study of chapter 2 is extended by investigating accumulation intervals shorter than daily scales. These are at 12, 8, 6, 4, 3, 2 and 1-hour accumulation intervals. It is shown that at shorter temporal scales the behavior of semi-variograms of precipitation still shows a clear seasonal trend. At hourly and two-hourly accumulation intervals the signal of the range becomes fairly constant during the summer due to the limited accumulation period, the frequent occurrence of convective precipitation, and measurement errors. This illustrates the lower limit of using cosine functions to describe variogram parameters. By fitting a power-law function through the different cosine parameters it is possible to describe the semi-variance of precipitation at scales between 1 and 24 hours using a limited set of equations. Chapter 4. Different sources of error affecting rainfall estimates by weather radar are identified. By focussing on precipitation near a C-band radar some of these sources are reduced, which allows to focus on a limited set of error sources. These are radar calibration, ground clutter, wet radome attenuation and variations in rain drop size distribution. An event that caused high precipitation amounts in a band along the center of the Netherlands and more than 50~mm near the radar between the 25th and the 27th of August 2010 is studied. Without any correction and by applying a standard Marshall-Palmer Z-R relation the radar is found to underestimate by approximately 50% with respect to the rain gauge measurements. Using the sun for calibration a correction of 1 dB is applied. Clutter is corrected by subtracting a clear sky clutter map as this proves to provide better results than the standard doppler filter. Wet-radome attenuation is corrected by looking at the amount of attenuation at a known strong clutter pixel near the radar. Disdrometer data near the radar are used to derive accurate Z-R relations specific to the precipitation of the event. These corrections combined provide very promising results with a slight overestimation of the quantitative precipitation estimates (QPE) from the radar by 5 to 8%. Chapter 5. An extensive dataset of 195 precipitation events measured by an X-band radar (SOLIDAR) is used to study precipitation at a high spatial resolution of 120 m and a high temporal resolution of 16 s. This study shows the benefit of using such high resolution X-band radars over flat terrain. The errors in the radar measurements are first assessed and corrected as well as possible by considering different techniques. These errors are calibration, ground clutter and attenuation. Finally, five strongly different precipitation events are studied in detail to illustrate the strengths and weaknesses of the X-band weather radar. Chapter 6. The variability and possible measurement methods of precipitation have been studied. It was shown that precipitation spatial and temporal variability has a clear statistical signal by analyzing variograms for different accumulation intervals. Weather radars were also shown to be able to give good estimates of precipitation at ground level as well as detailed information on the spatial variability. Some recommendations are given to perform follow up studies. For chapters 2 & 3 it is recommended to use a larger and more detailed dataset, which also incorporates Belgian and German data. This would allow the study of anisotropy in the semi-variograms as well as extending the analysis to accumulation times shorter than 1 hour and longer than 24 hours. For chapter 4 it is recommended to study pixels located further away from the radar. While other error sources would become more pronounced it would be possible to study the applicability of the proposed corrections at longer ranges. Studying the wet-radome attenuation with several strong clutter pixels near the radar would allow the study of wind-effects on wet-radome attenuation, possibly allowing corrections using measurements of (Doppler) wind-speed and direction. Finally, in chapter 5 it is recommended to study the successor of SOLIDAR, IDRA, which is currently operational at CESAR. This radar is a polarimetric radar, allowing a more detailed study of precipitation together with the data from other instruments at this location and the C-band radar of KNMI, which is located close to this location at approximately 23 km.

This thesis focuses specifically on weather radar rainfall measurements in strati form precipitation. In North-Western Europe this type of precipitation is most dominant in winter and leads to the largest hydro logical response of catchments. Unfortunately, the quality of uncorrected radar rainfall estimates starts decreasing at relatively close range from the radar for this type of precipitation. Therefore, as a first approach, a number of previously proposed radar error correction algorithms were applied in this thesis. The implementation of these methods shows a positive impact on the quality of the obtained precipitation measurements as compared to rain gauges. However, the traditional approach of applying a uniform Eulerian based algorithm for the entire radar umbrella to correct for VPR, limits its impact to improve the corrected weather radar precipitation measurements

Chapter 1. This thesis presents studies on the variability of precipitation in the Netherlands from datasets collected by radars, rain gauges and disdrometers. Accurate rainfall estimates are highly relevant in hydrology, meteorology and climatology as precipitation has a large impact on society. Precipitation has been studied extensively in the past, although it is impossible to describe all processes and behavior involved. This thesis attempts to add to the knowledge on precipitation. In the first chapter a short overview of rainfall variability at different scales is presented together with the most common instruments for measuring precipitation. Chapter 2. The spatial variability of daily rainfall accumulations is studied. Ninety-day averaged semi-variograms are created based on a 30-year data set gathered by automatic stations operated by the Royal Netherlands Meteorological Institute (KNMI). This is complemented by a one-year dataset of 10 gauges within a 5 km radius around CESAR (Cabauw Experimental Site for Atmospheric Research) in the center of the Netherlands. It is shown that it is possible to derive an average semi-variogram that describes the climatology of daily precipitation for each day of the year. Chapter 3. The study of chapter 2 is extended by investigating accumulation intervals shorter than daily scales. These are at 12, 8, 6, 4, 3, 2 and 1-hour accumulation intervals. It is shown that at shorter temporal scales the behavior of semi-variograms of precipitation still shows a clear seasonal trend. At hourly and two-hourly accumulation intervals the signal of the range becomes fairly constant during the summer due to the limited accumulation period, the frequent occurrence of convective precipitation, and measurement errors. This illustrates the lower limit of using cosine functions to describe variogram parameters. By fitting a power-law function through the different cosine parameters it is possible to describe the semi-variance of precipitation at scales between 1 and 24 hours using a limited set of equations. Chapter 4. Different sources of error affecting rainfall estimates by weather radar are identified. By focussing on precipitation near a C-band radar some of these sources are reduced, which allows to focus on a limited set of error sources. These are radar calibration, ground clutter, wet radome attenuation and variations in rain drop size distribution. An event that caused high precipitation amounts in a band along the center of the Netherlands and more than 50~mm near the radar between the 25th and the 27th of August 2010 is studied. Without any correction and by applying a standard Marshall-Palmer Z-R relation the radar is found to underestimate by approximately 50% with respect to the rain gauge measurements. Using the sun for calibration a correction of 1 dB is applied. Clutter is corrected by subtracting a clear sky clutter map as this proves to provide better results than the standard doppler filter. Wet-radome attenuation is corrected by looking at the amount of attenuation at a known strong clutter pixel near the radar. Disdrometer data near the radar are used to derive accurate Z-R relations specific to the precipitation of the event. These corrections combined provide very promising results with a slight overestimation of the quantitative precipitation estimates (QPE) from the radar by 5 to 8%. Chapter 5. An extensive dataset of 195 precipitation events measured by an X-band radar (SOLIDAR) is used to study precipitation at a high spatial resolution of 120 m and a high temporal resolution of 16 s. This study shows the benefit of using such high resolution X-band radars over flat terrain. The errors in the radar measurements are first assessed and corrected as well as possible by considering different techniques. These errors are calibration, ground clutter and attenuation. Finally, five strongly different precipitation events are studied in detail to illustrate the strengths and weaknesses of the X-band weather radar. Chapter 6. The variability and possible measurement methods of precipitation have been studied. It was shown that precipitation spatial and temporal variability has a clear statistical signal by analyzing variograms for different accumulation intervals. Weather radars were also shown to be able to give good estimates of precipitation at ground level as well as detailed information on the spatial variability. Some recommendations are given to perform follow up studies. For chapters 2 & 3 it is recommended to use a larger and more detailed dataset, which also incorporates Belgian and German data. This would allow the study of anisotropy in the semi-variograms as well as extending the analysis to accumulation times shorter than 1 hour and longer than 24 hours. For chapter 4 it is recommended to study pixels located further away from the radar. While other error sources would become more pronounced it would be possible to study the applicability of the proposed corrections at longer ranges. Studying the wet-radome attenuation with several strong clutter pixels near the radar would allow the study of wind-effects on wet-radome attenuation, possibly allowing corrections using measurements of (Doppler) wind-speed and direction. Finally, in chapter 5 it is recommended to study the successor of SOLIDAR, IDRA, which is currently operational at CESAR. This radar is a polarimetric radar, allowing a more detailed study of precipitation together with the data from other instruments at this location and the C-band radar of KNMI, which is located close to this location at approximately 23 km.

This thesis focuses specifically on weather radar rainfall measurements in strati form precipitation. In North-Western Europe this type of precipitation is most dominant in winter and leads to the largest hydro logical response of catchments. Unfortunately, the quality of uncorrected radar rainfall estimates starts decreasing at relatively close range from the radar for this type of precipitation. Therefore, as a first approach, a number of previously proposed radar error correction algorithms were applied in this thesis. The implementation of these methods shows a positive impact on the quality of the obtained precipitation measurements as compared to rain gauges. However, the traditional approach of applying a uniform Eulerian based algorithm for the entire radar umbrella to correct for VPR, limits its impact to improve the corrected weather radar precipitation measurements Uiteindelijk heb ik mij de afgelopen jaren voornamelijk gefocused op het verkrijgen van nauwkeurige neerslaginformatie uit weerradardata en de invloed van ruimtelijke variaties in druppelgrootteverdelingen. Dit blijkt toch niet zo eenvoudig te zijn, zoals u in dit proefschrift kunt lezen

Met het verzuringsmodel DEADM is voor het jaar 1993 voor Nederland en per verzuringsgebied de potentiele zure depositie berekend. Hierbij is gebruik gemaakt van voorlopige gevalideerde meetwaarden en van voorlopige cijfers voor de ammoniak-emissie. De resultaten van de DEADM berekening, die in dit rapport zijn beschreven, dienen derhalve ook als een voorlopige schatting te worden beschouwd. In dit rapport wordt de DEADM rekenmethode kort beschreven, alsmede de gebruikte invoer gegevens voor het model. De voorlopige schatting voor de potentiele zure depositie wordt uitgedrukt in zuur-equivalenten per hectare per jaar en bedraagt 4000 mol H+ ha-1 j-1. De voorlopige schattingen voor SOx, NOy, NHx en totaal N bedragen respectievelijk: 560, 970, 1910 en 2900 mol ha-1 j-1. De resultaten zijn gepresenteerd in de vorm van een vijftal kaarten en een tabel.

Met het verzuringsmodel DEADM is voor het jaar 1993 voor Nederland en per verzuringsgebied de potentiele zure depositie berekend. Hierbij is gebruik gemaakt van voorlopige gevalideerde meetwaarden en van voorlopige cijfers voor de ammoniak-emissie. De resultaten van de DEADM berekening, die in dit rapport zijn beschreven, dienen derhalve ook als een voorlopige schatting te worden beschouwd. In dit rapport wordt de DEADM rekenmethode kort beschreven, alsmede de gebruikte invoer gegevens voor het model. De voorlopige schatting voor de potentiele zure depositie wordt uitgedrukt in zuur-equivalenten per hectare per jaar en bedraagt 4000 mol H+ ha-1 j-1. De voorlopige schattingen voor SOx, NOy, NHx en totaal N bedragen respectievelijk: 560, 970, 1910 en 2900 mol ha-1 j-1. De resultaten zijn gepresenteerd in de vorm van een vijftal kaarten en een tabel.

This study on CH4, (its role in climate change and options for control), aimed at a scenario analysis to assess future climate change under reduced methane emissions. At the same time improving the quality of CH4 emission inventories and estimating the costs of emission reductions between 2010 and 2100. In this thesis 28 major options to control or mitigate methane emissions from different sources were identified. The effectiveness and costs of these options were assessed. This resulted in a database of different options and costs for all the different sources of methane. This database was subsequently used to update the methane module of the Integrated Model to Assess the Greenhouse Effect and expand it with a simple costing module. The IMAGE model was further improved by this work by Van Amstel on methane reduction strategies. The thesis concluded that significant reductions in global methane emissions are both technologically feasible and, in many cases, very cost effective strategies for climate change mitigation. Their wider implementation in coming years and decades will largely depend on the policy and market signals delivered by the UNFCCC conferences of the Parties, but failing to make full use of the potential for methane mitigation globally will inevitably make effective mitigation of climate change through reduction of carbon dioxide emissions alone all the more difficult. The scientific community can provide improved methane flux estimates, reduce uncertainties and enhance our understanding of key climate change feedback mechanisms, such as methane emissions from high latitude wetlands and from clathrate deposits. The technology to deliver deep cuts in methane emissions from a host of important sectors is already available. To put methane mitigation at the heart of a robust and well-integrated framework for tackling global climate change, improved national and international policy is required to facilitate rapid technology transfer and provide financial incentives that will ensure that the myriad potential opportunities for the effective mitigation of methane emissions around the world are made real. It is therefore recommended to remove market barriers and to increase attention for methane abatement options through international cooperation and learning from proven technology. One possible route to overcome market failure in methane reduction is international cooperation between front runners and countries willing to learn. Public-private partnerships can be used to stimulate this international cooperation for example in the International Methane Initiative.

This study on CH4, (its role in climate change and options for control), aimed at a scenario analysis to assess future climate change under reduced methane emissions. At the same time improving the quality of CH4 emission inventories and estimating the costs of emission reductions between 2010 and 2100. In this thesis 28 major options to control or mitigate methane emissions from different sources were identified. The effectiveness and costs of these options were assessed. This resulted in a database of different options and costs for all the different sources of methane. This database was subsequently used to update the methane module of the Integrated Model to Assess the Greenhouse Effect and expand it with a simple costing module. The IMAGE model was further improved by this work by Van Amstel on methane reduction strategies. The thesis concluded that significant reductions in global methane emissions are both technologically feasible and, in many cases, very cost effective strategies for climate change mitigation. Their wider implementation in coming years and decades will largely depend on the policy and market signals delivered by the UNFCCC conferences of the Parties, but failing to make full use of the potential for methane mitigation globally will inevitably make effective mitigation of climate change through reduction of carbon dioxide emissions alone all the more difficult. The scientific community can provide improved methane flux estimates, reduce uncertainties and enhance our understanding of key climate change feedback mechanisms, such as methane emissions from high latitude wetlands and from clathrate deposits. The technology to deliver deep cuts in methane emissions from a host of important sectors is already available. To put methane mitigation at the heart of a robust and well-integrated framework for tackling global climate change, improved national and international policy is required to facilitate rapid technology transfer and provide financial incentives that will ensure that the myriad potential opportunities for the effective mitigation of methane emissions around the world are made real. It is therefore recommended to remove market barriers and to increase attention for methane abatement options through international cooperation and learning from proven technology. One possible route to overcome market failure in methane reduction is international cooperation between front runners and countries willing to learn. Public-private partnerships can be used to stimulate this international cooperation for example in the International Methane Initiative.

Canonical community ordination comprises a collection of methods that relate species assemblages to their environment, in both observational studies and designed experiments. Canonical ordination differs from ordination sensu stricto in that species and environment data are analyzed simultaneously. Part I reviews the theory in a non-mathematical way with emphasis on new insights for the interpretation of ordination diagrams. The interpretation depends on the ordination method used to create the diagram. After the basic theory, Part I is focused on the ordination diagrams in linear methods of canonical community ordination, in particular principal component analysis, redundancy analysis and canonical correlation analysis. Special attention is devoted to the display of qualitative environmental variables.

De meest fundamentele en daarmee belangrijkste activiteit van hydrologen is het opstellen van waterbalansen. Immers, waterbalansen vormen het hart van elke watersysteemanalyse, inclusief het ontwikkelen, kalibreren en valideren van modellen. Naast de neerslag en verdamping vormen de aan- en afvoer van oppervlaktewater de belangrijkste componenten van de Nederlandse waterbalans. Die worden indirect afgeleid uit metingen bij klepstuwen, afsluiters, pompgemalen e.d. In dit artikel gaan wij in op de vraag hoe accuraat met zulke meetmethodes de debieten aan- en afvoeren in de praktijk kunnen worden geschat en hoe dit verbeterd kan worden. Wij concluderen dat de onzekerheden groot zijn en dat er veel te verbeteren is over het gehele traject: het uitvoeren van de metingen, het ijken van de formules van de meetopstellingen met alternatieve meetmethodes, de opslag en verwerking van de ruwe meetdata naar debieten en het kwantificeren van onzekerheden daarin.

For each of the instruments HGP7, CGM and CSB-Image-Meater a prediction formula for the percentage lean meat in a pig carcass was derived. Het mager-vleespercentage wordt geschat met behulp van een formule die in Nederland in de Hennessy Grading Probe (HGP) is ingebouwd. De huidige HGP2 is verouderd en onderhoud wordt niet langer door de leverancier ondersteund. Een ander apparaat is de Capteur Gras/Maigre – Sydel (CGM). Een relatief nieuwe meetmethode is het meten van de spek- en spierdikte op verschillende plaatsen op de doorsnede van het halve karkas m.b.v. beeldherkenning CSB-Image-Meater. De doelstelling is het opstellen van een schattingsformule van het vleespercentage voor de HGP7, CGM en CSB-Image-Meater volgens de EU-richtlijnen voor gelten, beren en borgen.

For each of the instruments HGP7, CGM and CSB-Image-Meater a prediction formula for the percentage lean meat in a pig carcass was derived.

In dit deel van de handleiding wordt ingegaan op schadedrempels. Exacte schadedrempels zijn helaas niet aan te geven, omdat veel andere factoren belangrijk zijn. Met behulp van de aangeboden informatie is het mogelijk om schaderisico's redelijk in te kunnen schatten.

In dit deel van de handleiding wordt ingegaan op schadedrempels. Exacte schadedrempels zijn helaas niet aan te geven, omdat veel andere factoren belangrijk zijn. Met behulp van de aangeboden informatie is het mogelijk om schaderisico's redelijk in te kunnen schatten.

Surface emissions of CO2 from fossil fuel combustion (¿FFCO2) are estimated for the Netherlands for the period of May 2006–June 2009 using ambient atmospheric observations taken at station Lutjewad in the Netherlands (6°21'E, 53°24'N, 1 m. a.s.l.). Measurements of ¿14C on 2-weekly integrations of CO2 and CO mixing ratios are combined to construct a quasi-continuous proxy record (FFCO2*) from which surface fluxes (¿FFCO2*) are determined using the 222Rn flux method. The trajectories of the air masses are analysed to determine emissions, which are representative for the Netherlands. We compared our observationally based estimates to the national inventories and we evaluated our methodology using the regional atmospheric transport model REMO. Based on 3 yr of observations we find annual mean ¿FFCO2* emissions of (4.7 ± 1.6) kt km-2 a-1 which is in very good agreement with the Dutch inventories of (4.5 ± 0.2) kt km-2 a-1 (average of 2006–2008).

Voor het bepalen van de kwaliteit van de bodem als hulpbron is er behoefte aan een regelmatige bepaling van de chemische en fysische eigenschappen, zowel in ruimte als tijd. Kwantitatieve schatting van de exacte hoeveelheid, ruimtelijke verdeling en temporele verandering van bodemeigenschappen is nog steeds een uitdaging. Het onderwerp van dit proefschrift is hoe spectrale reflectie informatie gelinkt kan worden aan bodemeigenschappen

Grondwater als leidraad voor de beheersing van het oppervlaktewaterpeil betekent dat de locatie van het grondwaterstandspeil optimaal moet zijn om droogte- en natschade voor de landbouw te beperken. Met behulp van een computermodel werd voor een voorbeeldpeilvak het effect van peilbeheer op de landbouwkundige opbrengsten gesimuleerd bij verschillende situeringen van het grondwaterstandspunt en vier verschillende beheersvarianten

Robustness of an object is defined as the probability that an object will have properties as required. Robustness Programming (RP) is a mathematical approach for Robustness estimation and Robustness optimisation. An example in the context of designing a food product, is finding the best composition of ingredients such that the product is optimally safe and is satisfying all specifications. Another example is the investment in a portfolio of stock market shares. The number of shares to invest in is typically a controllable factor. The future shares prices and resulting portfolio return are typically uncontrollable factors. It is interesting to find the composition of shares for which the probability of reaching a predefined target return is as high as possible. In this research alternative methods for Robustness Programming are developed with favourable optimisation properties for finding a design with a Robustness as high as possible. Some of these methods are generally applicable, while other methods use specific problem characteristics. A framework for Robustness Programming is developed for modelling design problems from a wide application area and to select the applicable RP methods for such design problems.

Robustness of an object is defined as the probability that an object will have properties as required. Robustness Programming (RP) is a mathematical approach for Robustness estimation and Robustness optimisation. An example in the context of designing a food product, is finding the best composition of ingredients such that the product is optimally safe and is satisfying all specifications. Another example is the investment in a portfolio of stock market shares. The number of shares to invest in is typically a controllable factor. The future shares prices and resulting portfolio return are typically uncontrollable factors. It is interesting to find the composition of shares for which the probability of reaching a predefined target return is as high as possible. In this research alternative methods for Robustness Programming are developed with favourable optimisation properties for finding a design with a Robustness as high as possible. Some of these methods are generally applicable, while other methods use specific problem characteristics. A framework for Robustness Programming is developed for modelling design problems from a wide application area and to select the applicable RP methods for such design problems.