Avulsion cycles and their stratigraphic signature on an experimental backwater‐controlled delta

River deltas grow in large part through repeated cycles of lobe construction and channel avulsion. Understanding avulsion cycles is important for coastal restoration and ecology, land management, and flood hazard mitigation. Emerging theories suggest that river avulsions on lowland deltas are controlled by backwater hydrodynamics; however, our knowledge of backwater-controlled avulsion cycles is limited. Here, we present results from an experimental delta that evolved under persistent backwater hydrodynamics achieved through variable flood discharges, shallow bed-slopes, and subcritical flows. The experimental avulsion cycles consisted of an initial phase of avulsion setup, an avulsion trigger, selection of a new flow path, and abandonment of the parent channel. Avulsions were triggered during the largest floods (78% of avulsions) after the channel was filled by a fraction (0.3 ± 0.13) of its characteristic flow depth at the avulsion site, which occurred in the upstream part of the backwater zone. The new flow path following avulsion was consistently one of the shortest paths to the shoreline, and channel abandonment occurred through temporal decline in water flow and sediment delivery to the parent channel. Experimental synthetic stratigraphy indicates that the bed thicknesses were maximum at the avulsion sites, consistent with our morphologic measurements of avulsion setup and the idea that there is a record of avulsion locations and thresholds in sedimentary rocks. Finally, we discuss the implications of our findings within the context of sustainable management of deltas, their stratigraphic record, and predicting avulsions on deltas

Reconstructions of deltaic environments from Holocene palynological records in the Volga delta, northern Caspian Sea

This article was made available through open access by the Brunel Open Access Publishing Fund.New palynological and ostracod data are presented from the Holocene Volga delta, obtained from short cores and surface samples collected in the Damchik region, near Astrakhan, Russian Federation in the northern Caspian Sea. Four phases of delta deposition are recognized and constrained by accelerated mass spectrometry (AMS) radiocarbon ages. Palynological records show that erosive channels, dunes (Baer hills) and inter-dune lakes were present during the period 11,500–8900 cal. BP at the time of the Mangyshlak Caspian lowstand. The period 8900–3770 cal. BP was characterized regionally by extensive steppe vegetation, with forest present at times with warmer, more humid climates, and with halophytic and xerophytic vegetation present at times of drought. The period 3770–2080 cal. BP was a time of active delta deposition, with forest or woodland close to the delta, indicating relatively warm and humid climates and variable Caspian Sea levels. From 2080 cal. BP to the present-day, aquatic pollen is frequent in highstand intervals and herbaceous pollen and fungal hyphae frequent in lowstand intervals. Soils and incised valley sediments are associated with the regional Derbent regression and may be time-equivalent with the ‘Medieval Warm Period’. Fungal spores are an indicator of erosional or aeolian processes, whereas fungal hyphae are associated with soil formation. Freshwater algae, ostracods and dinocysts indicate mainly freshwater conditions during the Holocene with minor brackish influences. Dinocysts present include Spiniferites cruciformis, Caspidinium rugosum, Impagidinium caspienense and Pterocysta cruciformis, the latter a new record for the Caspian Sea. The Holocene Volga delta is a partial analogue for the much larger oil and gas bearing Mio-Pliocene palaeo-Volga delta.Funding for the data collection and field work was provided from the following sources: 1 – IGCP-UNESCO 2003–2008 (Project 481 CASPAGE, Dating Caspian Sea Level Change); 2 – NWO, Netherlands Science Foundation and RFFI, Russian Science Foundation 2005–2008 (Programme: ‘VHR Seismic Stratigraphy and Paleoecology of the Holocene Volga Delta’); and 3 – BP Exploration (Caspian Sea) Sea Ltd. (Azeri-Chirag-Gunashli) 2005–2008 (‘Unravelling the Small-Scale Stratigraphy and Sediment Dynamics of the Modern Volga Delta Using VHR Marine Geophysics’). The palynological work was funded jointly by BP Exploration (Caspian Sea) Ltd., Delft University of Technology and KrA Stratigraphic Ltd. Ostracod analyses were funded by StrataData Ltd. and funding for two additional radiocarbon dates provided by Deltares

Assessment van Kinderen en jongeren: noodzaak om de blik te verruimen

Het onderwijs wordt geconfrnteerd met het dilemma om deprstaties en rendement van leerlingen te verhogen en anderzids ook iets te doen voor een groelend aantal uitvallers of onderpresteerders. Het Daffodil.project is een Europees Comenius- project is een Europees Comenius_multilateral samenwerkingsproject met partners uit 7 landen (Belgie, Hongarije, Zweden,Portugal, Noorwegen, Roemenie en de Britse Maagdeneilanden)met als doel een model te ontwikkelen dat bruikbaar is om het functioneren van kinderen met een probleem beter in kaart te brege

Towards a more functional and dynamic assessment of children with special needs in function of more inclusive education

Towards a more functional and dynamic assessment of children with special needs in function of more inclusive education - We present the Guidelines for Inclusive Assessment of children that experiment Special Educational Needs, developed by the DAFFODIL project team

The need for a more dynamic and ecological assessment of children experiencing barriers to learning to move towards inclusive education: a summary of results of the Daffodil project

Although governments have recognized the need to make education more accessible to children with developmental disabilities and/or learning difficulties, many children remain excluded from participation in regular school settings, let alone receive adequate education. Though every country which ratified the United Nations (UN) 2006 Convention on the Rights of People with Disability has committed itself to inclusive education, there are many obstacles. One of them is the currently preferred way of assessing children with standardized, psychometric diagnostic tests, with a comparative and classifying purpose. This type of assessment, based on a medical impairment model and a static model of intelligence, results in reports which are sometimes not very useful for educational advice. This paper reports an overview of the results of the DAFFODIL project (Dynamic Assessment of Functioning and Oriented at Development and Inclusive Learning), created by a consortium of eight European partners in order to research more inclusive alternatives and suggest reforms to assessment and coaching procedures. It starts with a critical review of current assessment practices; then it presents criteria for good practices for assessing children with additional educational needs in a more dynamic, inclusion-oriented and contextual way. A Delphi procedure was used by 150 professionals and parents to develop a consensus for guidelines for assessment procedures oriented at mapping functional difficulties, context, interaction and possibilities for learning, with the objective to understanding learning processes, to develop more inclusive, challenging and suitable educational programmes and more useful recommendations for teachers, parents and rehabilitation staff

Compound and hybrid clinothems of the last lowstand Mid-Adriatic Deep: Processes, depositional environments, controls and implications for stratigraphic analysis of prograding systems

Clinoforms with a range of scales are essential elements of prograding continental margins. Different types of clinoforms develop during margin growth, depending on combined changes in relative sea level, sediment supply and oceanographic processes. In studies of continental margin stratigraphy, trajectories of clinoform \u2018rollover\u2019 points are often used as proxies for relative sea-level variation and as predictors of the character of deposits beyond the shelf-break. The analysis of clinoform dynamics and rollover trajectory often suffers from the low resolution of geophysical data, the small scale of outcrops with respect to the dimensions of clinoform packages and low chronostratigraphic resolution. Here, through high-resolution seismic reflection data and sediment cores, we show how compound clinoforms were the most common architectural style of margin progradation of the late Pleistocene lowstand in the Adriatic Sea. During compound clinoform development, the shoreline was located landward of the shelf-break. It comprised a wave-dominated delta to the west and a barrier and back-barrier depositional system in the central and eastern area. Storm-enhanced hyperpycnal flows were responsible for the deposition of a sandy lobe in the river mouth, whereas a heterolithic succession formed elsewhere on the shelf. The storm-enhanced hyperpycnal flows built an apron of sand on the slope that interrupted an otherwise homogeneous progradational mudbelt. Locally, the late lowstand compound clinoforms have a flat to falling shelf-break trajectory. However, the main phase of shelf-break bypass and basin deposition coincides with a younger steeply rising shelf-break trajectory. We interpret divergence from standard models, linking shelf-break trajectory to deep-sea sand deposition, as resulting from a great efficiency of oceanographic processes in reworking sediment in the shelf, and from a high sediment supply. The slope foresets had a large progradational attitude during the late lowstand sea-level rise, showing that oceanographic processes can inhibit coastal systems to reach the shelf-edge. In general, our study suggests that where the shoreline does not coincide with the shelf-break, trajectory analysis can lead to inaccurate reconstruction of the depositional history of a margin

Integration of tetrapod-track taphonomic modes and taphonomic pathways with the Lake-basin type model

Lake systems contain outstanding sensitive integrated stratal records of environmental fluctuations that have been summarized in the lake-basin type (LBT) model. This model classified the stratigraphic record of ancient lake systems according to rates of potential accommodation relative to sediment+water supply. The LBT model convolved all modes and paths of water supply with amounts and types of sediment supply into a single basin-fill term (sediment+water) to provide widespread applicability.More recently, the model was enhanced and expanded. The elements of sediment+water supply were explicitly deconvolved (into through-flow, recharge, and discharge groundwater modes), the influence of the volume of sediment relative to water on lake hydrodynamics and ecosystems distinguished, and other parameters, such as invertebrate ichnofacies occurrence and distribution and groundwater hydrology, were integrated.Our detailed studies of vertebrate tetrapod tracks, their taphonomic modes, and ichnologic taphonomic pathways demonstrate their utility as sensitive indicators of environmental conditions of the track-bearing beds during imprinting and depositional processes in lacustrine systems. Three main tetrapod-track taphonomic-modes (TTTM) are defined based on the fidelity of anatomical features preservation: High-, Moderate-, and Low-fidelity. These modes strongly depend on the rheological condition of the sediment influenced by grain size distribution, mineralogy, stratal stacking at the bed scale, and moisture content?all of which are closely related to LBT, especially through the sediment+water supply factors.We propose integrating TTTM, ichnologic taphonomic pathways, and the spatial and stratigraphic distributions of vertebrate tracks with the LBT model to provide additional detailed insights into environmental and sedimentological conditions at the time of track imprinting. The wide array of Triassic Argentine paleolake records provide an excellent opportunity to characterize tetrapod footprint preservation and ichnofaunal taphonomic pathways in underfilled, balanced-filled, and overfilled lake-basins and to test this expansion of the LBT modFil: Mancuso, Adriana Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Krapovickas, Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Benavente, Cecilia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Marsicano, Claudia Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Bohacs, K.. No especifíca;International Association of Limnogeologists - International Paleolimnology Association Joint Meeting: Lagos, Memorias del TerritorioBarilocheArgentinaInternational Paleolimnological AssociationInternational Association of Limnogeologist