Hydrometeorological multi-model ensemble simulations of the 4 November 2011 flash flood event in Genoa, Italy, in the framework of the DRIHM Project
Hally, A. ; Caumont, O. ; Garrote, L. ; Richard, E. ; Weerts, A.H. ; Delogu, F. ; Fiori, E. ; Rebora, N. ; Parodi, A. ; Mihalovic, A. ; Ivkovic, M. ; Dekic, L. ; Verseveld, W.J. ; Nuissier, O. ; Ducrocq, V.P. ; Agostino, D. d'; Galizia, A. ; Danovaro, E. ; Clematis, A. - \ 2015
Natural Hazards and Earth System Sciences 15 (2015). - ISSN 1561-8633 - p. 537 - 555.
distributed hydrological model - convection-permitting ensemble - rainfall-runoff model - precipitating events - forecasting system - prediction system - extreme rainfall - mesoscale - scheme - parameterization
The e-Science environment developed in the framework of the EU-funded DRIHM project was used to demonstrate its ability to provide relevant, meaningful hydrometeorological forecasts. This was illustrated for the tragic case of 4 November 2011, when Genoa, Italy, was flooded as the result of heavy, convective precipitation that inundated the Bisagno catchment. The Meteorological Model Bridge (MMB), an innovative software component developed within the DRIHM project for the interoperability of meteorological and hydrological models, is a key component of the DRIHM e-Science environment. The MMB allowed three different rainfall-discharge models (DRiFt, RIBS and HBV) to be driven by four mesoscale limited-area atmospheric models (WRF-NMM, WRF-ARW, Meso-NH and AROME) and a downscaling algorithm (RainFARM) in a seamless fashion. In addition to this multi-model configuration, some of the models were run in probabilistic mode, thus giving a comprehensive account of modelling errors and a very large amount of likely hydrometeorological scenarios (> 1500). The multi-model approach proved to be necessary because, whilst various aspects of the event were successfully simulated by different models, none of the models reproduced all of these aspects correctly. It was shown that the resulting set of simulations helped identify key atmospheric processes responsible for the large rainfall accumulations over the Bisagno basin. The DRIHM e-Science environment facilitated an evaluation of the sensitivity to atmospheric and hydrological modelling errors. This showed that both had a significant impact on predicted discharges, the former being larger than the latter. Finally, the usefulness of the set of hydrometeorological simulations was assessed from a flash flood early-warning perspective.
Effects of Irrigation in India on the Atmospheric Water Budget
Tuinenburg, O.A. ; Hutjes, R.W.A. ; Stacke, T. ; Wiltshire, A. ; Lucas-Picher, P. - \ 2014
Journal of Hydrometeorology 15 (2014)3. - ISSN 1525-755X - p. 1028 - 1050.
soil-moisture - part i - precipitation - climate - monsoon - scheme - models - cycle - parameterization - representation
The effect of large-scale irrigation in India on the moisture budget of the atmosphere was investigated using three regional climate models and one global climate model, all of which performed an irrigated run and a natural run without irrigation. Using a common irrigation map, year-round irrigation was represented by adding water to the soil moisture to keep it at 90% of the maximum soil moisture storage capacity, regardless of water availability. For two focus regions, the seasonal cycle of irrigation matched that of the reference dataset, but irrigation application varied between the models by up to 0.8 mm day(-1). Because of the irrigation, evaporation increased in all models, but precipitation decreased because of a strong decrease in atmospheric moisture convergence. A moisture tracking scheme was used to track individual evaporated moisture parcels through the atmosphere to determine where these lead to precipitation. Up to 35% of the evaporation moisture from the Ganges basin is recycling within the river basin. However, because of a decreased moisture convergence into the river basin, the total amount of precipitation in the Ganges basin decreases. Although a significant fraction of the evaporation moisture recycles within the river basin, the changes in large-scale wind patterns due to irrigation shift the precipitation from the eastern parts of India and Nepal to the northern and western parts of India and Pakistan. In these areas where precipitation increases, the relative precipitation increase is larger than the relative decrease in the areas where precipitation decreases. It is concluded 1) that the direct effects of irrigation on precipitation are small and are not uniform across the models; 2) that a fraction of up to 35% of any marginal evaporation increase (for example, due to irrigation) will recycle within the river basin; and 3) that when irrigation is applied on a large scale, the dominant effect will be a change in large-scale atmospheric flow that decreases precipitation in eastern India and increases it in western and northern India.
Global water resources affected by human interventionss and climate change
Haddeland, I. ; Heinke, J. ; Biemans, H. ; Eisner, S. ; Florke, M.F. ; Hanasaki, N. ; Konzmann, M. ; Ludwig, F. - \ 2014
Proceedings of the National Academy of Sciences of the United States of America 111 (2014)9. - ISSN 0027-8424 - p. 3251 - 3256.
integrated model - bias correction - surface-water - validation - fluxes - scheme
Humans directly change the dynamics of the water cycle through dams constructed for water storage, and through water withdrawals for industrial, agricultural, or domestic purposes. Climate change is expected to additionally affect water supply and demand. Here, analyses of climate change and direct human impacts on the terrestrial water cycle are presented and compared using a multimodel approach. Seven global hydrological models have been forced with multiple climate projections, and with and without taking into account impacts of human interventions such as dams and water withdrawals on the hydrological cycle. Model results are analyzed for different levels of global warming, allowing for analyses in line with temperature targets for climate change mitigation. The results indicate that direct human impacts on the water cycle in some regions, e.g., parts of Asia and in the western United States, are of the same order of magnitude, or even exceed impacts to be expected for moderate levels of global warming (+2 K). Despite some spread in model projections, irrigation water consumption is generally projected to increase with higher global mean temperatures. Irrigation water scarcity is particularly large in parts of southern and eastern Asia, and is expected to become even larger in the future.
Land atmosphere feedbacks and their role in the water resources of the Ganges basin
Harding, R.J. ; Blyth, E.M. ; Tuinenburg, O.A. ; Wiltshire, A. - \ 2013
Science of the Total Environment 468-469 (2013). - ISSN 0048-9697 - p. S85 - S92.
asian summer monsoon - mixed-layer model - soil-moisture - climate-change - variability - evaporation - irrigation - precipitation - regions - scheme
The northern Indian subcontinent has frequently been identified as a hotspot for land atmosphere interactions. It is also a region with the highest concentration of irrigated land and highest (and increasing) population density in the world. The available water in the region with which to grow food depends on the Asian monsoon, groundwater and melt from Himalayan snows. Any changes or disruptions to these sources of water could threaten the food supply. It is therefore essential to understand how the land surface, and in particular irrigated land, interacts with the atmosphere. It is anticipated that the interactions will occur on many scales. To an extent the magnitude and form of these will depend on the depth of the atmosphere which is affected. Thus at the local, or micro, scale it is the surface layer (some 10s m deep) which is cooled and moistened by the evaporation of irrigated water, at the meso-scale the Planetary boundary layer (up to 1 or 2 km) will be modified with possible atmospheric moistening, increased cloud and rain formation and at very large scales the whole dynamics of the south Asian Monsoon will be affected. This illustrates a strong interaction between the Asian monsoon and the regional topography. Of considerable significance is the finding in this paper that up to 60% of the evaporation from irrigated areas in the summer months is ultimately recycled to Himalayan rainfall and so feedbacks to river flows in the Ganges. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.
Farm choice between agri-environmental contracts in the European Union
Peerlings, J.H.M. ; Polman, N.B.P. - \ 2009
Journal of Environmental Planning and Management 52 (2009)5. - ISSN 0964-0568 - p. 593 - 612.
participation - scheme
The purpose of this paper is to analyse land allocation between competing agri-environmental contracts, taking into account institutional issues, the characteristics of the farm and farm household. Three types of agri-environmental contract are considered: a Biodiversity Protection Contract, a Landscape Management Contract and a Restriction on Intensive Practices Contract. The paper demonstrates that it is important to study the choices made between the different agri-environmental contracts. The reasons for this are that a unit of land can only be allocated to one contract (although the farm itself can choose to hold more than one contract) and the perceived relative marginal cost of a contract can change if the institutional setting, the farm household or the farm characteristics alter. The model uses a two-stage method. As a first stage, the probability of contract choice is determined. In the second stage these probabilities are linked to costs and the optimal contract choice is determined.
Analysis of Model Results for the Turning of the Wind and Related Momentum Fluxes in the Stable Boundary Layer
Svensson, G. ; Holtslag, A.A.M. - \ 2009
Boundary-Layer Meteorology 132 (2009)2. - ISSN 0006-8314 - p. 261 - 277.
large-eddy simulation - turbulence - scheme
The turning of wind with height and the related cross-isobaric (ageostrophic) flow in the thermally stable stratified boundary layer is analysed from a variety of model results acquired in the first Global Energy and Water Cycle Experiment (GEWEX) Atmospheric Boundary Layer Study (GABLS1). From the governing equations in this particular simple case it becomes clear that the cross-isobaric flow is solely determined by the surface turbulent stress in the direction of the geostrophic wind for the quasi-steady state conditions under consideration. Most models indeed seem to approach this relationship but for very different absolute values. Because turbulence closures used in operational models typically tend to give too deep a boundary layer, the integrated total cross-isobaric mass flux is up to three times that given by research numerical models and large-eddy simulation. In addition, the angle between the surface and the geostrophic wind is typically too low, which has important implications for the representation of the larger-scale flow. It appears that some models provide inconsistent results for the surface angle and the momentum flux profile, and when the results from these models are removed from the analysis, the remaining ten models do show a unique relationship between the boundary-layer depth and the surface angle, consistent with the theory given. The present results also imply that it is beneficial to locate the first model level rather close to the surface for a proper representation of the turning of wind with height in the stable boundary layer
Turbulent dispersion in cloud-topped boundary layers
Verzijlbergh, R.A. ; Jonker, H.J.J. ; Heus, T. ; Vilà-Guerau de Arellano, J. - \ 2009
Atmospheric Chemistry and Physics 9 (2009)4. - ISSN 1680-7316 - p. 1289 - 1302.
large-eddy simulation - shallow cumulus clouds - plume dispersion - relative dispersion - models - stratocumulus - statistics - transport - scheme
Compared to dry boundary layers, dispersion in cloud-topped boundary layers has received less attention. In this LES based numerical study we investigate the dispersion of a passive tracer in the form of Lagrangian particles for four kinds of atmospheric boundary layers: 1) a dry convective boundary layer (for reference), 2) a "smoke" cloud boundary layer in which the turbulence is driven by radiative cooling, 3) a stratocumulus topped boundary layer and 4) a shallow cumulus topped boundary layer. We show that the dispersion characteristics of the smoke cloud boundary layer as well as the stratocumulus situation can be well understood by borrowing concepts from previous studies of dispersion in the dry convective boundary layer. A general result is that the presence of clouds enhances mixing and dispersion ¿ a notion that is not always reflected well in traditional parameterization models, in which clouds usually suppress dispersion by diminishing solar irradiance. The dispersion characteristics of a cumulus cloud layer turn out to be markedly different from the other three cases and the results can not be explained by only considering the well-known top-hat velocity distribution. To understand the surprising characteristics in the shallow cumulus layer, this case has been examined in more detail by 1) determining the velocity distribution conditioned on the distance to the nearest cloud and 2) accounting for the wavelike behaviour associated with the stratified dry environment
Institutional design of agri-environmental contracts in the European Union: the role of trust and social capital.
Polman, N.B.P. ; Slangen, L.H.G. - \ 2008
NJAS Wageningen Journal of Life Sciences 55 (2008)4. - ISSN 1573-5214 - p. 413 - 430.
landbouwbeleid - besluitvorming - contracten - motivatie - agrarisch natuurbeheer - agricultural policy - decision making - contracts - motivation - agri-environment schemes - farmer participation - scheme - information - governance - policy - rules
Assessing potential uptake of agri-environmental schemes based on farm and farmer characteristics only results in an incomplete analysis because it neglects the effects of motivational issues of the institutional design of contracts, as set up by the government, and of social capital. In this paper we describe contract choice using a trivariate probit model and taking into account farm and farmer characteristics and motivational issues. Motivational issues in this study include the perception of institutional design, the use of extension services, trust in the government, and preferences for stable policies. Results show that besides farm and farmer characteristics these factors are important for the likelihood of enrolling in agri-environmental contracts. They do not influence every contract type in the same way and further decisions to conclude different contract types are connected. If farmers perceive the design of an agri-environmental scheme as weak or favour a stable policy they are less likely to conclude contracts for biodiversity protection. Farmers who do not trust the government are less likely to conclude contracts for less intensive practices. Involvement in general networks increases the probability of contracting for wildlife and landscape management and less intensive practices whereas this factor is not important for biodiversity protection. The results suggest that taking into account motivational issues and differentiating towards different contract types can increase effectiveness and efficiency of agri-environmental schemes.
Wind engineering in Africa
Wisse, J.A. ; Stigter, C.J. - \ 2007
Journal of Wind Engineering and Industrial Aerodynamics 95 (2007)9-11. - ISSN 0167-6105 - p. 908 - 927.
semiarid northern nigeria - design - speed - sand - establishment - consequences - windbreaks - shelter - scheme - tunnel
The International Association for Wind Engineering (IAWE) has very few contacts in Africa, the second-largest continent. This paper reviews important wind-related African issues. They all require data on wind climate, which are very sparse in Africa. Wind engineering in Africa can assist in collecting data on wind climate, developing wind energy, reducing the adverse effects of wind and related drifting sand in building activities and agriculture, and limiting other wind-related disasters, in environment and ecology, such as those caused by erosion and fire. The paper aims to encourage Africa-oriented supportive research, especially better data coverage; quality control of existing data; search of historical archives; generation of data by numerical weather analyses; and validation of extrapolation techniques. We envisage promising cooperation with Africa, despite the fact that African countries do not currently participate in the international exchange and cooperation in these fields. African priorities presently seem to be different, while funds and other facilities are lacking. Capacity building in wind engineering and support issues should be initiated by agencies such as UNEP, FAO, EU, WMO, NGOs, etc. The necessity of professional wind engineering input in these activities should also be recognized. Interaction of IAWE with these agencies is necessary
Single-Column Model Intercomparison for a Stably Stratified Atmospheric Boundary Layer
Cuxart, J. ; Holtslag, A.A.M. ; Beare, R.J. ; Bazile, E. ; Beljaars, A. ; Cheng, A. ; Conangla, L. ; Ek, M.B. ; Freedman, F. ; Hamdi, R. ; Kerstein, A. ; Kitagawa, H. ; Lenderink, G. ; Lewellen, D. ; Mailhot, J. ; Mauritsen, T. ; Perov, V. ; Schayes, G. ; Steeneveld, G.J. ; Svensson, G. ; Taylor, P. ; Weng, W. ; Wunsch, S. ; Xu, K.M. - \ 2006
Boundary-Layer Meteorology 118 (2006)2. - ISSN 0006-8314 - p. 273 - 303.
turbulence closure-model - large-eddy simulation - part i - scheme - parameterization - formulation - diffusion - dynamics - surfaces - system
The parameterization of the stably stratified atmospheric boundary layer is a difficult issue, having a significant impact on medium-range weather forecasts and climate integrations. To pursue this further, a moderately stratified Arctic case is simulated by nineteen single-column turbulence schemes. Statistics from a large-eddy simulation intercomparison made for the same case by eleven different models are used as a guiding reference. The single-column parameterizations include research and operational schemes from major forecast and climate research centres. Results from first-order schemes, a large number of turbulence kinetic energy closures, and other models were used. There is a large spread in the results; in general, the operational schemes mix over a deeper layer than the research schemes, and the turbulence kinetic energy and other higher-order closures give results closer to the statistics obtained from the large-eddy simulations. The sensitivities of the schemes to the parameters of their turbulence closures are partially explored
An improved Kalman Smoother for atmospheric inversions
Bruhwiler, L. ; Michalak, A. ; Peters, W. ; Baker, D. ; Tans, P.P. - \ 2005
Atmospheric Chemistry and Physics 5 (2005). - ISSN 1680-7316 - p. 2691 - 2702.
carbon-dioxide - trace gases - co2 sources - transport - sensitivity - models - sinks - emissions - scheme - cycle
We explore the use of a fixed-lag Kalman smoother for sequential estimation of atmospheric carbon dioxide fluxes. This technique takes advantage of the fact that most of the information about the spatial distribution of sources and sinks is observable within a few months to half of a year of emission. After this period, the spatial structure of sources is diluted by transport and cannot significantly constrain flux estimates. We therefore describe an estimation technique that steps through the observations sequentially, using only the subset of observations and modeled transport fields that most strongly constrain the fluxes at a particular time step. Estimates of each set of fluxes are sequentially updated multiple times, using measurements taken at different times, and the estimates and their uncertainties are shown to quickly converge. Final flux estimates are incorporated into the background state of CO2 and transported forward in time, and the final flux uncertainties and covariances are taken into account when estimating the covariances of the fluxes still being estimated. The computational demands of this technique are greatly reduced in comparison to the standard Bayesian synthesis technique where all observations are used at once with transport fields spanning the entire period of the observations. It therefore becomes possible to solve larger inverse problems with more observations and for fluxes discretized at finer spatial scales. We also discuss the differences between running the inversion simultaneously with the transport model and running it entirely off-line with pre-calculated transport fields. We find that the latter can be done with minimal error if time series of transport fields of adequate length are pre-calculated.
An updated length-scale formulation for turbulent mixing in clear and cloudy boundary layers
Lenderink, G. ; Holtslag, A.A.M. - \ 2004
Quarterly Journal of the Royal Meteorological Society 130 (2004)604. - ISSN 0035-9009 - p. 3405 - 3427.
grenslaagmeteorologie - wolken - turbulentie - kinetische energie - boundary-layer meteorology - clouds - turbulence - kinetic energy - shallow cumulus convection - large-eddy simulation - atmospheric models - parameterization - scheme - stratocumulus - fluxes - transport - impacts - wind
A new mixing-length scale is presented for turbulence-closure schemes, with special emphasis on neutral-to-convective conditions in clear and cloudy boundary layers. The length scale is intended for a prognostic turbulent-kinetic-energy closure. It is argued that present-day length-scale formulations may easily fail in one of two limiting situations. Schemes based on a local stability measure (e.g.the Richardson number) display unrealistic behaviour and instabilities in the convective limit. This strongly limits the representation of mixing in cloudy boundary layers. On the other hand, it is shown that non-local parcel methods may misrepresent mixing near the surface. The new length-scale formulation combines local and non-local stability in a new way; it uses vertical integrals over the stability (the Richardson number) in a simple 'parcel' framework. The length scale matches with surface-layer similarity for near-neutral conditions and displays a realistic convective limit. The use of the length-scale formulation can be extended easily to cloudy boundary layers. The scheme is numerically stable and computationally cheap. The behaviour of the length scale is evaluated in a single-column model (SCM) and in a high-resolution limited-area model (LAM). The SCM shows good behaviour in three cases with and without boundary-layer clouds. The prediction of the near-surface wind and temperature in the LAM compares favourably with tower measurements at Cabauw (the Netherlands).
Air movement and its consequences around a multiple shelterbelt system under advective conditions in semi-arid northern Nigeria.
Onyewotu, L.O.Z. ; Stigter, C.J. ; Oladipo, E.O. ; Owonubi, J.J. - \ 2004
Theoretical and Applied Climatology 79 (2004)3-4. - ISSN 0177-798X - p. 255 - 262.
sand - windbreaks - millet - scheme - crop
Horizontal wind speed patterns above a scarce millet row crop on inhomogeneous sandy soil revealed insufficient protection from hot winds by multiple shelterbelts in semi-arid Northern Nigeria. This appeared mainly due to too high distances between the belts. Marked yield drops occurred with distance between the belts, in what McNaughton defined (under mechanical damage and microclimate disturbance from strong winds) as the unprotected wake zone. These may, in the case of hot winds, mainly be attributed to combined negative effects on soil moisture and crop physiology of the combination of turbulence, worsened by the shelterbelts, and advected heat. Other parameters confirm the picture of the wake zone and the quiet zone, the latter also being present windward of the belts in a reduced form. The results have serious consequences for the design rules of multiple shelterbelts and alternatives under African semi-arid conditions.
The effect of irrigated rice cropping on the alkalinity of two alkaline rice soils in the Sahel
Asten, P.J.A. van; Zelfde, J.A. van 't; Zee, S.E.A.T.M. van der; Hammecker, C. - \ 2004
Geoderma 119 (2004)3-4. - ISSN 0016-7061 - p. 233 - 247.
saline-sodic soil - forage cultivation - reclamation - gypsum - dissolution - scheme - crops - field - zone
Irrigated rice cropping is practiced to reclaim alkaline-sodic soils in many parts of the world. This practice is in apparent contrast with earlier studies in the Sahel, which suggests that irrigated rice cropping may lead to the formation of alkaline-sodic soils. Soil column experiments were done with some of Sahel's most alkaline-sodic rice soils from the Office du Niger (Mali) and Foum Gleita (Mauritania). Soils were irrigated using non-saline carbonate-rich irrigation water typical for the Sahel and percolation was maintained at 3-4 mm day(-1). After one cropping season, soils had turned from sodic to non-sodic, and pH had dramatically decreased, most notably in the upper soil layers. The changes were most important in the Office du Niger soil due to its small buffering capacity (small CEC and CaCO3). Alkalinity consumed by above-ground matter of the rice plants (grain and straw) equaled or exceeded alkalinity added via irrigation in a zero percolation scenario. Hence, for a climate and irrigation water that are typical for the Sahel, removal of straw and grain prevents or substantially reduces further alkalinization of the soils if percolation is absent. However, in case of some percolation, straw can best be incorporated in the topsoil of calcareous soils as it accelerates de-alkalinization and de-sodication through increased dissolution of calcite. No evidence was found indicating that ferrolysis altered the short-term alkalinity balance of the studied soils to any extent. Our results are in line with recent field studies and suggest a de-alkalinization of sodic-alkaline flooded (rice) soils in the Sahel. (C) 2003 Elsevier B.V. All rights reserved.
Computer-assisted analysis and epidemiological value of genotyping methods for Campylobacter jejuni and Campylobacter coli
Boer, P. de; Duim, B. ; Rigter, A. ; Jacobs-Reitsma, W.F. ; Wagenaar, J.A. - \ 2000
Journal of Clinical Microbiology 38 (2000)5. - ISSN 0095-1137 - p. 1940 - 1946.
fragment-length-polymorphism - field gel-electrophoresis - broiler flocks - poultry - dna - scheme - recombination - serotypes - humans - clones
For epidemiological tracing of the thermotolerant Campylobacter species C. jejuni and C. coli, reliable and highly discriminatory typing techniques are necessary. In this study the genotyping techniques of flagellin typing (flaA typing), pulsed-field gel electrophoresis (PFGE), automated ribotyping, and amplified fragment length polymorphism (AFLP) fingerprinting were compared. The following aspects were compared: computer-assisted analysis, discriminatory power, and use for epidemiological typing of campylobacters. A set of 50 campylobacter poultry isolates from The Netherlands and neighboring countries was analyzed. Computer-assisted analysis made cluster analysis possible and eased the designation of different genotypes. AFLP fingerprinting was the most discriminatory technique, identifying 41 distinct genotypes, while PFGE identified 38 different types, flaA typing discriminated 31 different types, and ribotyping discriminated 26 different types. Furthermore, AFLP analysis was the most suitable method for computer-assisted data analysis. In some cases combining the results of AFLP fingerprinting, PFGE, and flaA typing increased our ability to differentiate strains that appeared genetically related. We conclude that AFLP is a highly discriminatory typing method and well suited for computer-assisted data analysis; however, for optimal typing of campylobacters, a combination of multiple typing methods is needed