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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    Educational differences in healthy, environmentally sustainable and safe food consumption among adults in the Netherlands
    Bussel, Lenneke M. Van; Rossum, Caroline T.M. Van; Temme, Elisabeth H.M. ; Boon, Polly E. ; Ocké, Marga C. - \ 2020
    Public Health Nutrition (2020). - ISSN 1368-9800
    24-h recall - Educational level - Environmentally sustainable food - Food consumption - Food safety - Healthy food

    Objective:To assess the differences in healthy, environmentally sustainable and safe food consumption by education levels among adults aged 19-69 in the Netherlands.Design:This study used data from the Dutch National Food Consumption Survey 2007-10. Food consumption data were obtained via two 24-h recalls. Food consumption data were linked to data on food composition, greenhouse gas emissions (GHGe) and concentrations of contaminants. The Dutch dietary guidelines (2015), dietary GHGe and dietary exposure to contaminants were used as indicators for healthy, environmentally sustainable and safe food consumption, respectively.Setting:The Netherlands.Participants:2106 adults aged 19-69 years.Results:High education groups consumed significantly more fruit (+28 g), vegetables (men +22 g; women +27 g) and fish (men +6 g; women +7 g), and significantly less meat (men -33 g; women -14 g) compared with low education groups. Overall, no educational differences were found in total GHGe, although its food sources differed. Exposure to contaminants showed some differences between education groups.Conclusions:The consumption patterns differed by education groups, resulting in a more healthy diet, but equally environmentally sustainable diet among high compared with low education groups. Exposure to food contaminants differed between education groups, but was not above safe levels, except for acrylamide and aflatoxin B1. For these substances, a health risk could not be excluded for all education groups. These insights may be used in policy measures focusing on the improvement of a healthy diet for all.

    Extrapolation of a structural equation model for digital soil mapping
    Angelini, M.E. ; Kempen, B. ; Heuvelink, G.B.M. ; Temme, A.J.A.M. ; Ransom, M.D. - \ 2020
    Geoderma 367 (2020). - ISSN 0016-7061
    Homosoil - Pedometrics - Soil spatial variation - Soil-forming factors - Validation

    In theory, two separate regions with the same soil-forming factors should develop similar soil conditions. This theoretical finding has been used in digital soil mapping (DSM) to extrapolate a model from one area to another, which usually does not work out well. One reason for failure could be that most of these studies used empirical methods. Structural equation modelling (SEM) is a semi-mechanistic technique, which can explicitly include expert knowledge. We therefore hypothesize that SEM models are more suitable for extrapolation than purely empirical models in DSM. The objective of this study was to investigate the extrapolation capability of SEM by comparing different model settings. We applied a SEM model from a previous study in Argentina to a similar soil-landscape in the Great Plains of the United States to predict clay, organic carbon, and cation exchange capacity for three major horizons: A, B, and C. We concluded that system relationships that were well supported by pedological knowledge showed consistent and equal behaviour in both study areas. In addition, a deeper understanding of indicators of soil-forming factors could strengthen conceptual models for extrapolating DSM models. We also found that for model extrapolation, knowledge-based links between system variables are more effective than data-driven links. In particular, model modifications can improve local prediction but harm the predictive power of extrapolation.

    Dynamic path-dependent landslide susceptibility modelling
    Samia, Jalal ; Temme, Arnaud ; Bregt, Arnold ; Wallinga, Jakob ; Guzzetti, Fausto ; Ardizzone, Francesca - \ 2020
    Natural Hazards and Earth System Sciences 20 (2020)1. - ISSN 1561-8633 - p. 271 - 285.
    This contribution tests the added value of including landslide path dependency in statistically based landslide susceptibility modelling. A conventional pixel-based landslide susceptibility model was compared with a model that includes landslide path dependency and with a purely path-dependent landslide susceptibility model. To quantify path dependency among landslides, we used a space–time clustering (STC) measure derived from Ripley's space–time K function implemented on a point-based multi-temporal landslide inventory from the Collazzone study area in central Italy. We found that the values of STC obey an exponential-decay curve with a characteristic timescale of 17 years and characteristic spatial scale of 60 m. This exponential space–time decay of the effect of a previous landslide on landslide susceptibility was used as the landslide path-dependency component of susceptibility models. We found that the performance of the conventional landslide susceptibility model improved considerably when adding the effect of landslide path dependency. In fact, even the purely path-dependent landslide susceptibility model turned out to perform better than the conventional landslide susceptibility model. The conventional plus path-dependent and path-dependent landslide susceptibility model and their resulting maps are dynamic and change over time, unlike conventional landslide susceptibility maps.
    Reconstructing rates and patterns of colluvial soil redistribution in agrarian (hummocky) landscapes
    Meij, Marijn van der; Reimann, Tony ; Temme, A.J.A.M. ; Wallinga, J. ; Beek, R. van; Sommer, M. - \ 2019
    Earth Surface Processes and Landforms 44 (2019)12. - ISSN 0197-9337 - p. 2408 - 2422.
    Humans have triggered or accelerated erosion processes since prehistoric times through agricultural practices. Optically stimulated luminescence (OSL) is widely used to quantify phases and rates of the corresponding landscape change, by measuring the last moment of daylight exposure of sediments. However, natural and anthropogenic mixing processes, such as bioturbation and tillage, complicate the use of OSL as grains of different depositional ages become mixed, and grains become exposed to light even long after the depositional event of interest. Instead, OSL determines the stabilization age, indicating when sediments were buried below the active mixing zone. These stabilization ages can cause systematic underestimation when calculating deposition rates. Our focus is on colluvial deposition in a kettle hole in the Uckermark region, northeastern Germany. We took 32 samples from five locations in the colluvium filling the kettle hole to study both spatial and temporal patterns in colluviation. We combined OSL dating with advanced age modelling to determine the stabilization age of colluvial sediments. These ages were combined with an archaeological reconstruction of historical ploughing depths to derive the levels of the soil surface at the moment of stabilization; the deposition depths, which were then used to calculate unbiased deposition rates. We identified two phases of colluvial deposition. The oldest deposits (~5 ka) were located at the fringe of the kettle hole and accumulated relatively slowly, whereas the youngest deposits (<0.3 ka) rapidly filled the central kettle hole with rates of two orders of magnitude higher. We suggest that the latter phase is related to artificial drainage, facilitating accessibility in the central depression for agricultural practices. Our results show the need for numerical dating techniques that take archaeological and soil‐geomorphological information into account to identify spatiotemporal patterns of landscape change, and to correctly interpret landscape dynamics in anthropogenically influenced hilly landscapes.
    Spatial early warning signals for impending regime shifts : A practical framework for application in real-world landscapes
    Nijp, Jelmer J. ; Temme, Arnaud J.A.M. ; Voorn, George A.K. van; Kooistra, Lammert ; Hengeveld, Geerten M. ; Soons, Merel B. ; Teuling, Adriaan J. ; Wallinga, Jakob - \ 2019
    Global Change Biology 25 (2019)6. - ISSN 1354-1013 - p. 1905 - 1921.
    alternative stable states - critical slowing down - early warning signals - ecosystem resilience - environmental change - landscapes - regime shifts - remote sensing - spatial patterns - tipping points

    Prediction of ecosystem response to global environmental change is a pressing scientific challenge of major societal relevance. Many ecosystems display nonlinear responses to environmental change, and may even undergo practically irreversible ‘regime shifts’ that initiate ecosystem collapse. Recently, early warning signals based on spatiotemporal metrics have been proposed for the identification of impending regime shifts. The rapidly increasing availability of remotely sensed data provides excellent opportunities to apply such model-based spatial early warning signals in the real world, to assess ecosystem resilience and identify impending regime shifts induced by global change. Such information would allow land-managers and policy makers to interfere and avoid catastrophic shifts, but also to induce regime shifts that move ecosystems to a desired state. Here, we show that the application of spatial early warning signals in real-world landscapes presents unique and unexpected challenges, and may result in misleading conclusions when employed without careful consideration of the spatial data and processes at hand. We identify key practical and theoretical issues and provide guidelines for applying spatial early warning signals in heterogeneous, real-world landscapes based on literature review and examples from real-world data. Major identified issues include (1) spatial heterogeneity in real-world landscapes may enhance reversibility of regime shifts and boost landscape-level resilience to environmental change (2) ecosystem states are often difficult to define, while these definitions have great impact on spatial early warning signals and (3) spatial environmental variability and socio-economic factors may affect spatial patterns, spatial early warning signals and associated regime shift predictions. We propose a novel framework, shifting from an ecosystem perspective towards a landscape approach. The framework can be used to identify conditions under which resilience assessment with spatial remotely sensed data may be successful, to support well-informed application of spatial early warning signals, and to improve predictions of ecosystem responses to global environmental change.

    Author Correction: The potential of future foods for sustainable and healthy diets
    Parodi, A. ; Leip, A. ; Boer, I.J.M. De; Slegers, P.M. ; Ziegler, F. ; Temme, E.H.M. ; Herrero, M. ; Tuomisto, H. ; Valin, H. ; Middelaar, C.E. Van; Loon, J.J.A. Van; Zanten, H.H.E. Van - \ 2019
    Nature Sustainability 2 (2019)4. - ISSN 2398-9629 - p. 342 - 347.

    In the version of this Article originally published, in Supplementary Table 7, the energy and land-use values for mealworms in Thevenot et al. were mistakenly swapped. The correct values are 65.39 MJ for energy use and 4.31 m 2 for land use. In the same table, the energy and land use values for black soldier fly in Salome et al. were incorrectly given as 0.14 MJ and 41.67 m 2 ; they should have read 7.248 MJ and 0.024 m 2 (respectively). Correcting these values has led to corresponding changes in Fig. 3, Supplementary Figs 2 and 4 and Supplementary Table 8. Additionally, in the panel of Fig. 3 that contains information about vitamin A, the land-use values of 593 for pork and 1914 for beef were incorrect, and should have been 666 and 3238, respectively.

    The potential of future foods for sustainable and healthy diets
    Parodi, Alejandro ; Leip, Adrian ; Boer, I.J.M. de; Slegers, P.M. ; Ziegler, Friederike ; Temme, Elisabeth H.M. ; Herrero, Mario ; Tuomisto, Hanna ; Valin, Hugo ; Middelaar, C.E. van; Loon, J.J.A. van; Zanten, H.H.E. van - \ 2019
    In: Trade-offs in Science : Keeping the Balance. - Wageningen University & Research - p. 35 - 35.
    Altering diets is increasingly acknowledged as an important solution to feed the world’s growing population within the planetary boundaries. In our search for a planet-friendly diet, the main focus has been on eating more plant-source foods, and eating no or less animal-source foods, while the potential of future foods, such as insects, seaweed or cultured meat has been underexplored. Here we show that compared to current animal-source foods, future foods have major environmental benefits while safeguarding the intake of essential micronutrients. The complete array of essential nutrients in the mixture of future foods makes them good-quality alternatives for current animal-source foods compared to plant-source foods. Moreover, future foods are land-efficient alternatives for animal-source foods, and if produced with renewable energy, they also offer greenhouse gas benefits. Further research on nutrient bioavailability and digestibility, food safety, production costs and consumer acceptance will determine their role as main food sources in future diets.
    The potential of future foods for sustainable and healthy diets
    Parodi, A. ; Leip, A. ; Boer, I.J.M. De; Slegers, P.M. ; Ziegler, F. ; Temme, E.H.M. ; Herrero, M. ; Tuomisto, H. ; Valin, H. ; Middelaar, C.E. Van; Loon, J.J.A. Van; Zanten, H.H.E. Van - \ 2018
    Nature Sustainability 1 (2018). - ISSN 2398-9629 - p. 782 - 789.
    Altering diets is increasingly acknowledged as an important solution to feed the world’s growing population within the planetary boundaries. In our search for a planet-friendly diet, the main focus has been on eating more plant-source foods, and eating no or less animal-source foods, while the potential of future foods, such as insects, seaweed or cultured meat has been underexplored. Here we show that compared to current animal-source foods, future foods have major environmental benefits while safeguarding the intake of essential micronutrients. The complete array of essential nutrients in the mixture of future foods makes them good-quality alternatives for current animal-source foods compared to plant-source foods. Moreover, future foods are land-efficient alternatives for animal-source foods, and if produced with renewable energy, they also offer greenhouse gas benefits. Further research on nutrient bioavailability and digestibility, food safety, production costs and consumer acceptance will determine their role as main food sources in future diets.
    Vleesconsumptie in Nederland: gedrag gedraagt zich anders dan gedacht
    Dagevos, H. ; Temme, L. - \ 2018
    Voeding Nu 20 (2018)8. - ISSN 1389-7608 - p. 8 - 11.
    Landslide path dependency and its impact on space-time modelling of landslide susceptibility
    Samia, Jalal - \ 2018
    Wageningen University. Promotor(en): A.K. Bregt; J. Wallinga, co-promotor(en): A.J.A.M. Temme. - Wageningen : Wageningen University - ISBN 9789463435147 - 135

    In this PhD thesis, I characterized and quantified the spatiotemporal effects of path dependency among landslides in Collazzone study area, in Umbria region, central Italy, and that means landslides themselves increase the susceptibility for future landslides. Such effects was strong in about a decade with an exponential decay response over time. In this aspect, a modified time-variant landslide susceptibility model was proposed reflecting the spatiotemporal effects of landslide path dependency. The effect of landslide path dependency was better captured in pixel-based landslide susceptibility models, and improved the performance and accuracy of these models substantially.

    On the role of hydrologic processes in soil and landscape evolution modeling : concepts, complications and partial solutions
    Meij, W.M. van der; Temme, A.J.A.M. ; Lin, H.S. ; Gerke, H.H. ; Sommer, M. - \ 2018
    Earth-Science Reviews 185 (2018). - ISSN 0012-8252 - p. 1088 - 1106.

    The ability of water to transport and transform soil materials is one of the main drivers of soil and landscape development. In turn, soil and landscape properties determine how water is distributed in soil landscapes. Understanding the complex dynamics of this co-evolution of soils, landscapes and the hydrological system is fundamental in adapting land management to changes in climate. Soil-Landscape Evolution Models (SLEMs) are used to simulate the development and evolution of soils and landscapes. However, many hydrologic processes, such as preferential flow and subsurface lateral flow, are currently absent in these models. This limits the applicability of SLEMs to improve our understanding of feedbacks in the hydro-pedo-geomorphological system. Implementation of these hydrologic processes in SLEMs faces several complications related to calculation demands, limited methods for linking pedogenic and hydrologic processes, and limited data on quantification of changes in the hydrological system over time. In this contribution, we first briefly review processes and feedbacks in soil-landscape-hydrological systems. Next, we elaborate on the development required to include these processes in SLEMs. We discuss the state-of-the-art knowledge, identify complications, give partial solutions and suggest important future development. The main requirements for incorporating hydrologic processes in SLEMs are: (1) designing a model framework that can deal with varying timescales for different sets of processes, (2) developing and implementing methods for simulating pedogenesis as a function of water flow, (3) improving and implementing knowledge on the evolution and dynamics of soil hydraulic properties over different timescales, and (4) improving the database on temporal changes and dynamics of flow paths.

    Implementing landslide path dependency in landslide susceptibility modelling
    Samia, J. ; Temme, A.J.A.M. ; Bregt, A.K. ; Wallinga, J. ; Stuiver, H.J. ; Guzzetti, Fausto ; Ardizzone, Francesca ; Rossi, Mauro - \ 2018
    Landslides 15 (2018)11. - ISSN 1612-510X - p. 2129 - 2144.
    Landslide susceptibility modelling — a crucial step towards the assessment of landslide hazard and risk — has hitherto not included the local, transient effects of previous landslides on susceptibility. In this contribution, we implement such transient effects, which we term "landslide path dependency', for the first
    time. Two landslide path dependency variables are used to characterise transient effects: a variable reflecting how likely it is that an earlier landslide will have a follow-up landslide and a variable reflecting the decay of transient effects over time. These two landslide path dependency variables are considered in addition
    to a large set of conditioning attributes conventionally used in landslide susceptibility. Three logistic regression models were trained and tested fitted to landslide occurrence data from a multi-temporal landslide inventory: (1) a model with only conventional variables, (2) a model with conventional plus landslide path dependency variables, and (3) a model with only landslide path
    dependency variables. We compare the model performances, differences in the number, coefficient and significance of the selected variables, and the differences in the resulting susceptibility maps. Although the landslide path dependency variables are highly significant and have impacts on the importance of other variables, the performance of the models and the susceptibility maps do not substantially differ between conventional and conventional plus path dependent models. The path dependent landslide susceptibility model, with only two explanatory variables, has lower model performance, and differently patterned susceptibility map than the two other models. A simple landslide susceptibility model using only DEM-derived variables and landslide path dependency variables performs better than the path dependent landslide susceptibility model, and almost as well as the model with conventional
    plus landslide path dependency variables — while avoiding the need for hard-to-measure variables such as land use or lithology. Although the predictive power of landslide path dependency variables is lower than those of the most important conventional variables, our findings provide a clear incentive to further explore landslide path dependency effects and their potential role in landslide susceptibility modelling.
    The effect of landform variation on vegetation patterning and related sediment dynamics
    Baartman, J.E.M. ; Temme, A.J.A.M. ; Saco, Patricia - \ 2018
    Earth Surface Processes and Landforms 43 (2018)10. - ISSN 0197-9337 - p. 2121 - 2135.
    Semi‐arid ecosystems are often spatially self‐organized in typical patterns of vegetation bands with high plant cover interspersed with bare soil areas, also known as ‘tiger bush’. In modelling studies, most often, straight planar slopes were used to analyse vegetation patterning. The effect of slope steepness has been investigated widely, and some studies investigated the effects of microtopography and hillslope orientation. However, at the larger catchment scale, the overall form of the landscape may affect vegetation patterning and these more complex landscapes are much more prevalent than straight slopes. Hence, our objective was to determine the effect of landform variation on vegetation patterning and sediment dynamics. We linked two well‐established models that simulate (a) plant growth, death and dispersal of vegetation, and (b) erosion and sedimentation dynamics. The model was tested on a straight planar hillslope and then applied to (i) a set of simple synthetic topographies with varying curvature and (ii) three more complex, real‐world landscapes of distinct morphology. Results show banded vegetation patterning on all synthetic topographies, always perpendicular to the slope gradient. Interestingly, we also found that movement of bands – a debated phenomenon – seems to be dependent on curvature. Vegetation banding was simulated on the slopes of the alluvial fan and along the valley slopes of the dissected and rolling landscapes. In all landscapes, local valleys developed a full vegetation cover induced by water concentration, which is consistent with observations worldwide. Finally, banded vegetation patterns were found to reduce erosion significantly as compared to other vegetation configurations.
    Modeling and assessing the effects of land use changes on runoff generation with the CLUE-s and WetSpa models
    Mohammady, Majid ; Moradi, Hamid Reza ; Zeinivand, Hossein ; Temme, A.J.A.M. ; Yazdani, Mohammad Reza ; Pourghasemi, Hamid Reza - \ 2018
    Theoretical and Applied Climatology 133 (2018)1-2. - ISSN 0177-798X - p. 459 - 471.

    Land use change is an important determinant of hydrological processes and is known to affect hydrological parameters such as runoff volume, flood frequency, base flow, and the partitioning into surface flow and subsurface flow. The main objective of this research was to assess the magnitude of the effect of land use changes on runoff parameters, using the Baghsalian watershed in Iran as a case study site. At first, land use maps of years 1986 and 2012 were prepared using synthetic method, and then simulation was done based on land use changes in the 1986 to 2012 period. Land use map of year 2030 was simulated using CLUE-s model. Spatially distributed hydrological WetSpa model was used to simulate runoff at daily scale with land use maps of 1986, 2012, and 2030. Total volume of runoff, peak flow, and surface flow were compared. The accuracy of the WetSpa model simulation was assessed with the Nash-Sutcliffe efficiency, which had values of 0.61 and 0.56% for the calibration and validation dataset, respectively. The aggregation measure criterion was also calculated and had values of 64 and 62% for the calibration and validation periods, respectively. The main land use changes in Baghsalian watershed between 1986, 2012, and 2030 were the conversion of forest and rangeland to agriculture and residential land use types. Because of these conversions, simulated total runoff volume increased; and the rate of increase in surface runoff was larger than the rate of increase in subsurface runoff. In addition, surface and subsurface runoff increased in 2012 and 2030 compared to 1986 land use map, but the rate of increase of subsurface runoff was less than surface runoff.

    Getting a grip on hydrological and sediment connectivity
    Masselink, Rens J.H. - \ 2017
    Wageningen University. Promotor(en): C.J. Ritsema; S.E.A.T.M. van der Zee, co-promotor(en): S.D. Keesstra; A.J.A.M. Temme. - Wageningen : Wageningen University - ISBN 9789463436342 - 158
    hydrology - sediment - land degradation - slopes - geological sedimentation - land management - soil physics - hydrologie - sediment - landdegradatie - hellingen - geologische sedimentatie - grondbeheer - bodemfysica

    Land degradation is a large problem worldwide, especially in agricultural areas. Between 1-6 billion ha of land worldwide is affected by land degradation. With an increasing world population, more food production is needed and, therefore, more land is converted into agricultural areas. This conversion of land to agricultural areas, in turn, leads to more land degradation. Some common forms of land degradation are desertification, salinization and soil erosion by water. The negative effects of soil erosion have been recognized for a long time. Since the early 20th century, researchers have tried to quantify soil displaced due to water, and to measure and model the efficiency of management strategies.

    The implications of problems with upscaling, wrong process representation and equifinality include the difficulty to properly predict sediment sources, pathways and sinks within catchments. These problems then can translate into the implementation of sub-optimal management strategies. To deal with these non-linear processes and the lack of proper representation of water and sediment sources, pathways and sinks, the concept of connectivity was developed. Currently, many definitions of connectivity have been proposed, although the definition most used is that of hydrological connectivity by Pringle (2003): ‘Hydrologic connectivity is the water-mediated transport of matter, energy and organisms within or between elements of the hydrologic cycle’.

    A unified theory on what constitutes connectivity and how connectivity should be measured or inferred remains one of the biggest challenges within catchment science. In addition, it is unclear whether connectivity should be an output or an input of a model and if an input, whether this should be added explicitly or implicitly. The main objective of this thesis was, therefore, to assess and quantify hydrological and sediment connectivity in a meaningful way, which can further our understanding of hydrological and sediment transport processes and catchment system dynamics.

    The study was carried out in three catchments in Navarre, northern Spain. Two catchments, ‘Latxaga’ and ‘La Tejeria’, are agricultural catchments with sizes of 2.07 km2 and 1.69 km2, respectively. The ‘Oskotz Forestal’ catchment is a (semi-)natural catchment, with a size of 5.05 km2. Land cover in the agricultural catchments is mainly winter wheat and barley, while in the Oskotz catchment it is grassland and forest. Latxaga and La Tejeria are mainly underlain by marls and within La Tejeria some sandstone is also present. The geology in Oskotz is characterised by an alternation of marls and sandy limestone.

    In chapter 2, I used networks (graph theory) to characterise and quantify overland flow connectivity dynamics on hillslopes in a humid sub-Mediterranean environment by using a combination of high-resolution digital-terrain models, overland flow sensors and a network approach. Results showed that there are significant differences between overland flow connectivity on agricultural areas and semi-natural shrubs areas. Significant positive correlations between connectivity and precipitation characteristics were found. Significant negative correlations between connectivity and soil moisture were found, most likely due to soil water repellency and/or soil surface crusting. The combination of structural networks and dynamic networks for determining potential connectivity and actual connectivity proved a powerful tool for analysing overland flow connectivity.

    In chapter 3, I determined the functioning of hillslope-channel connectivity and the continuation of transport of these sediments in the channel. To determine this functioning, I obtained data on sediment transport from the hillslopes to the channels while simultaneously looking at factors that influence sediment export out of the catchment. For measuring hillslope-channel sediment connectivity, Rare-Earth Oxide (REO) tracers were applied to a hillslope in the Latxaga catchment preceding the winter of 2014-2015. The results showed that during the winter there have been no sediments transported from the hillslope into the channel. Analysis of precipitation data showed that although total precipitation quantities did not differ much from the mean, the precipitation intensities were low. Using a Random Forest (RF) machine learning method, I showed that hillslope-channel connectivity in Latxaga is dominated by sediment mobilisation during large (high intensity) precipitation events. Sediments are for a large part exported during those events. Large events also leave behind large amounts of sediments in and near the channel, which is gradually removed by small events.

    In chapter 4 I demonstrated that existing data can be used to assess governing factors of connectivity, and how these factors change over time. Data from three catchments in Navarre, Northern Spain, were used to assess factors that influence hydrologic and sediment connectivity. These factors were used as components in a spatially-lumped linear model for discharge and suspended-sediment yield. Three components of connectivity were distinguished: topographical, biological and soil. Changes in the topographical component for the studied periods were considered relatively small, and, therefore, kept constant. Changes in the biological component were determined using the Normalised Difference Vegetation Index. Changes in the soil component were assessed using an Antecedent Precipitation Index. Nash-Sutcliffe model efficiency coefficients were between 0.49 through 0.62 for the discharge models and between 0.23 through 0.3 for the sediment-yield models. I recommended applying the model at smaller spatial scales than catchment scale to minimize the lumping of spatial variability in the components.

    In chapter 5, the objective was to better understand the implications of model calibration at different spatial scales on the simulation of hydrology and sediment dynamics of an agricultural catchment. I applied the LAPSUS-D model to the Latxaga catchment. The model was calibrated and validated (4 years: 2011-2015) using three datasets at varying spatial scales: hillslope, catchment and the combined dataset (combined-calibrated model). The hillslope-calibrated model showed mainly infiltration-excess overland flow, the catchment-calibrated mainly saturation-excess overland flow at the footslopes and the combined-calibrated model showed saturation-excess overland flow from the midslopes to the footslopes. For hydrology, the combined-calibrated model simulated the large discharge peaks best, while at the hillslope scale, the hillslope-calibrated model performed best. The hillslope-calibrated model produced the highest model efficiencies for sediments, for calibration (0.618) and validation (0.269). The hillslope-calibrated model was the only model that showed observed gully erosion on a high-resolution DEM and displayed channel sediment dynamics. However, absolute quantities of erosion and deposition within the catchment were too high. The results show that modellers need to be aware of problems associated with automatic calibration, over-calibration and not incorporating measured data at multiple spatial scales. We advocate incorporating runoff and sediment tracing data at multiple scales whenever this is possible and to, furthermore, carry out specific measuring campaigns towards this end, ultimately to get a more comprehensive view on hydrological and sediment connectivity within a catchment.

    The combination of chapters in this thesis showed that the connectivity concept is useful for a wide range of studies, from hillslope scale to catchment scale. Using the concept, I was able to determine sediment dynamics for a humid-Mediterranean catchment and show that this behaviour is different than previously thought.

    Depending of the aim of the study, various concepts of connectivity are useful. Different geologic and climatic settings cause large differences in catchment (sediment) dynamics. It might, therefore, not be necessary, or even possible, to strive for a single, unifying conceptual framework for connectivity. Instead, a collection of frameworks for different settings should be developed. These frameworks should, however, always aim at helping to understand which measurements need to be taken and which type of models and indices should be used for that particular setting.

    It is my honest opinion that connectivity is definitely a useful concept to advance our knowledge on water and sediment transport processes further. However, careful consideration is also required as this particular concept will not necessary provide the ultimate explanation and insights in dynamic behaviour within watersheds around the world. The gap between the different spatial and temporal scales is too complex to be bridged with a single concept like connectivity. However, the many studies about connectivity that will be published in the near future will be able to advance knowledge on water and sediment transport processes.

    Topography reconstruction of eroding landscapes – A case study from a hummocky ground moraine (CarboZALF-D)
    Meij, W.M. van der; Temme, A.J.A.M. ; Wallinga, J. ; Hierold, W. ; Sommer, M. - \ 2017
    Geomorphology 295 (2017). - ISSN 0169-555X - p. 758 - 772.
    Erosion processes, aggravated by human activity, have a large impact on the spatial variation of soil and topographic properties. Knowledge of the topography prior to human-induced erosion (paleotopography) in naturally stable landscapes is valuable for identifying vulnerable landscape positions and is required as starting point for erosion modelling exercises. However, developing accurate reconstructions of paleotopography provide a major challenge for geomorphologists. Here, we present a set of paleotopographies for a closed kettle hole catchment in north-east Germany (4 ha), obtained through different reconstruction approaches. Current soil and colluvium thickness, estimated from a dataset of 264 soil descriptions using Ordinary Kriging, were used as input for a mass balance, or were compared with a set of undisturbed soil thicknesses to estimate the amount of erosion. The performance of the different approaches was assessed with cross-validation and the count of mispredicted eroded, depositional or stable landscape positions.

    The paleotopographic reconstruction approach based on the average thickness of undisturbed soils in the study area showed the best performance. This thickness (1.00 m) is comparable to the average undisturbed soil thickness in the region and in line with global correlations of soil thickness as a function of rainfall and initial CaCO3 content. The performance of the different approaches depended more on mispredictions of landscape position due to the assumption of a spatially constant initial soil depth than on small variations in this depth. To conclude, we mention several methodological and practical points of attention for future topography reconstruction studies, concerning data quality and availability, spatial configuration of data and other processes affecting topography.
    Does a better adherence to dietary guidelines reduce mortality risk and environmental impact in the Dutch sub-cohort of the European Prospective Investigation into Cancer and Nutrition?
    Biesbroek, Sander ; Verschuren, W.M.M. ; Boer, Jolanda M.A. ; Kamp, Mirjam E. van de; Schouw, Yvonne T. Van Der; Geelen, Anouk ; Looman, Moniek ; Temme, Elisabeth H.M. - \ 2017
    The British journal of nutrition 118 (2017)1. - ISSN 0007-1145 - p. 69 - 80.
    Dietary Approaches to Stop Hypertension - Dutch Healthy Diet index 2015 - Environmental impact - Healthy Diet Indicator - Mortality risk - Sustainable and healthy diets
    Guidelines for a healthy diet aim to decrease the risk of chronic diseases. It is unclear as to what extent a healthy diet is also an environmentally friendly diet. In the Dutch sub-cohort of the European Prospective Investigation into Cancer and Nutrition, the diet was assessed with a 178-item FFQ of 40 011 participants aged 20–70 years between 1993 and 1997. The WHO’s Healthy Diet Indicator (HDI), the Dietary Approaches to Stop Hypertension (DASH) score and the Dutch Healthy Diet index 2015 (DHD15-index) were investigated in relation to greenhouse gas (GHG) emissions, land use and all-cause mortality risk. GHG emissions were associated with HDI scores (−3·7 % per sd increase (95 % CI −3·4, −4·0) for men and −1·9 % (95 % CI −0·4, −3·4) for women), with DASH scores in women only (1·1 % per sd increase, 95 % CI 0·9, 1·3) and with DHD15-index scores (−2·5 % per sd increase (95 % CI −2·2, −2·8) for men and −2·0 % (95 % CI −1·9, −2·2) for women). For all indices, higher scores were associated with less land use (ranging from −1·3 to −3·1 %). Mortality risk decreased with increasing scores for all indices. Per sd increase of the indices, hazard ratios for mortality ranged from 0·88 (95 % CI 0·82, 0·95) to 0·96 (95 % CI 0·92, 0·99). Our results showed that adhering to the WHO and Dutch dietary guidelines will lower the risk of all-cause mortality and moderately lower the environmental impact. The DASH diet was associated with lower mortality and land use, but because of high dairy product consumption in the Netherlands it was also associated with higher GHG emissions.
    Valorando la conectividad ladera-cauce en una cuenca agrícola, utilizando óxidos de tierras raras como trazadores y modelos de selvas aleatorias
    Masselink, R.J.H. ; Temme, A.J.A.M. ; Giménez, R. ; Casalí, J. ; Keesstra, S.D. - \ 2017
    Cuadernos de Investigacion Geografica 43 (2017)1. - ISSN 0211-6820 - p. 19 - 39.
    Hillslope-channel connectivity - Mediterranean - Random forests - Sediment tracing

    Soil erosion from agricultural areas is a large problem, because of off-site effects like the rapid filling of reservoirs. To mitigate the problem of sediments from agricultural areas reaching the channel, reservoirs and other surface waters, it is important to understand hillslope-channel connectivity and catchment connectivity. To determine the functioning of hillslope-channel connectivity and the continuation of transport of these sediments in the channel, it is necessary to obtain data on sediment transport from the hillslopes to the channels. Simultaneously, the factors that influence sediment export out of the catchment need to be studied. For measuring hillslope-channel sediment connectivity, Rare-Earth Oxide (REO) tracers were applied to a hillslope in an agricultural catchment in Navarre, Spain, preceding the winter of 2014-2015. The results showed that during the winter no sediment transport from the hillslope to the channel was detected. To test the implication of the REO results at the catchment scale, two contrasting conceptual models for sediment connectivity were assessed using a Random Forest (RF) machine learning method. The RF method was applied using a 15-year period of measured sediment output at the catchment scale. One model proposes that small events provide sediment for large events, while the other proposes that only large events cause sediment detachment and small events subsequently remove these sediments from near and in the channel. For sediment yield prediction of small events, variables related to large preceding events were the most important. The model for large events underperformed and, therefore, we could not draw any immediate conclusions whether small events influence the amount of sediment exported during large events. Both REO tracers and RF method showed that low intensity events do not contribute any sediments from the hillslopes to the channel in the Latxaga catchment. Sediment dynamics are dominated by sediment mobilisation during large (high intensity) events. Sediments are for a large part exported during those events, but the system shows a memory of the occurrence of these large events, suggesting that large amounts of sediments are deposited in and near the channel after these events. These sediments are gradually removed by small events. To better understand the delivery of sediments to the channel and how large and small events influence each other more field data on hillslope-channel connectivity and within-channel sediment dynamics is necessary.

    Developing, choosing and using landscape evolution models to inform field-based landscape reconstruction studies
    Temme, A.J.A.M. ; Armitage, J. ; Attal, M. ; Gorp, Wouter van; Coulthard, T.J. ; Schoorl, J.M. - \ 2017
    Earth Surface Processes and Landforms 42 (2017)13. - ISSN 0197-9337 - p. 2167 - 2183.
    Calibration and validation - Complexity - Landscape evolution model - Landscape reconstruction

    Landscape evolution models (LEMs) are an increasingly popular resource for geomorphologists as they can operate as virtual laboratories where the implications of hypotheses about processes over human to geological timescales can be visualized at spatial scales from catchments to mountain ranges. Hypothetical studies for idealized landscapes have dominated, although model testing in real landscapes has also been undertaken. So far however, numerical landscape evolution models have rarely been used to aid field-based reconstructions of the geomorphic evolution of actual landscapes. To help make this use more common, we review numerical landscape evolution models from the point of view of model use in field reconstruction studies. We first give a broad overview of the main assumptions and choices made in many LEMs to help prospective users select models appropriate to their field situation. We then summarize for various timescales which data are typically available and which models are appropriate. Finally, we provide guidance on how to set up a model study as a function of available data and the type of research question.

    Development and evaluation of the Dutch Healthy Diet index 2015
    Looman, M. ; Feskens, E.J.M. ; Rijk, M.G. de; Meijboom, S. ; Briesbroek, S. ; Temme, E.H.M. ; Vries, J.H.M. de; Geelen, M.M.E.E. - \ 2017
    Public Health Nutrition 20 (2017)13. - ISSN 1368-9800 - p. 2289 - 2299.
    To update the Dutch Healthy Diet index, a measure of diet quality, to reflect adherence to the Dutch dietary guidelines 2015 and to evaluate against participants’ characteristics and nutrient intakes with the score based on 24 h recall (24 hR) data and FFQ data.
    The Dutch Healthy Diet index 2015 (DHD15-index) consists of fifteen components representing the fifteen food-based Dutch dietary guidelines of 2015. Per component the score ranges between 0 and 10, resulting in a total score between 0 (no adherence) and 150 (complete adherence).
    Wageningen area, the Netherlands, 2011–2013.
    Data of 885 men and women, aged 20–70 years, participating in the longitudinal NQplus study, who filled out two 24 hR and one FFQ, were used.
    Mean (sd) score of the DHD15-index was 68·7 (16·1) for men and 79·4 (16·0) for women. Significant inverse trends were found between the DHD15-index and BMI, smoking, and intakes of energy, total fat and saturated fat. Positive trends were seen across sex-specific quintiles of the DHD15-index score with energy-adjusted micronutrient intakes. Mean DHD15-index score of the FFQ data was 15·5 points higher compared with 24 hR data, with a correlation coefficient of 0·56 between the scores. Observed trends of the DHD15-index based on FFQ with participant characteristics, macronutrient and energy-adjusted micronutrient intakes were similar to those with the DHD15-index based on 24 hR.
    The DHD15-index score assesses adherence to the Dutch dietary guidelines 2015 and indicates diet quality. The DHD15-index score can be based on 24 hR data and on FFQ data.
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