climatic fluctuations reflected in the evolution of fluvial systems of central eastern europe 60 8 ka cal bp abstract in general the evolution of fluvial systems in central eastern europe reflects the main phases of climatic changes during the period of 60 8 ka cal bp registered in greenland ice cores and their isotopic 18 o curves the greenland isotope curve shows many more wiggles and stages than the fluvial record of the same time especially during the interpleniglacial phase in central eastern europe we observe several deviations from those climatic trends connected with different factors among which are the long distance of the region from the atlantic ocean and an increase in continentality at times this region was occupied by permafrost although the coexisting warm summers during a part of the studied period enabled the presence of a forest cover these factors together controlled the specific features of the fluvial regime and sediment load reflected in alternating trends to erosion or aggradation and from meandering to braiding the permafrost influenced snowmelt floods and tendency to braiding the dense vegetation with trees reduced the supply of sediments and stabilized the meandering channels very distinct changes occurred in the river valleys that drain the mountains where ceaseless fluctuations of vegetation vertical zones were present especially during the unstable interpleniglacial when the supply of load from the higher vegetation zones was increased this system controlled by the climate and plant vegetation was modified by other factors including tectonics wind activity during dry periods blocking of valleys by ice sheets meltwater supply and sea level fluctuations of two reservoirs

fluvial responses to tectonics and climate change during the late weichselian in the eastern part of the pannonian basin hungary abstract fine grained sandy silty channel belt and floodplain deposits of the berettyo koros rivers a main eastern transverse tributary system of the modern tisza river in the eastern part of the pannonian basin were deposited during the late pleistocene under net subsiding conditions the palaeo drainage network pattern of a 2500 km 2 large part of the alluvial plain was reconstructed based on interpretation of airborne photographs and analysis of 18th century topographic maps which show the natural river patterns that predate the introduction of river regulation schemes the investigation showed that a large meandering river system with two main channel belts surrounding a floodbasin entered the alluvial plain from the northeast and a braided river entered the alluvial plain from the southeast detailed sedimentary logs of seven continuous corings and several sand and clay pit sections were used to characterize different alluvial units optical luminescence dating osl of 25 quartz samples and four 14 c datings showed that the sediments are of late pleniglacial to late glacial age transport directions inferred from heavy mineral analyses combined with the osl ages strongly suggest that the large meandering system represents the palaeo tisza river which supposedly flowed along the northeast southwest striking ermellek depression during the late pleniglacial the braided river can be regarded as a precursor to the fekete and feher koros rivers which entered the alluvial plain from the southeast during the late glacial the interpretation of seismic profiles field measurements of neotectonic activity and variations in thickness of sediments along the studied profile revealed that river development was largely controlled by subsidence along the ermellek depression until 14 to 16 ky and by uplift of the southeastern part of the catchment area the studied fluvial successions also document the response of the palaeo tisza and koros system to the climate changes of the weichselian late pleniglacial late glacial period much of the sand from the meandering zones was deposited during the bolling allerod and sagvar lascaux interstadials whereas some dated sand units from the braided zone represent the older and younger dryas the error ranges of osl dates which often exceed the duration of weichselian substages and subdivisions prevented an unambiguous correlation of the studied sections with the millennial scale climate changes of the last 25 ky meandering and braided river activity coexisted under different climate conditions whereas locations of the main channel belts are related to subsidence anomalies the results of our study thus clearly indicate that tectonics was the primary control on river development

intersite comparison of interannual nearshore bar behavior 1 long term years bathymetric data sets collected in six multiple near shore sandbar systems were analyzed with complex empirical orthogonal function analysis to quantify intersite differences and similarities in cyclic offshore progressive bar behavior the observations came from a 37 year annually sampled data set of four regions along the dutch coast spanning 70 km of coastline an 18 year fortnightly to monthly sampled data set at duck north carolina alongshore extent 1 km and a 7 year daily sampled data set of a single cross shore profile at the hasaki coast of japan the first complex mode typically representing 50 70 of the total depth variance described the long term offshore progressive behavior and allowed for an objective separation of the barred part of the profile from the shoreward and seaward located nonbarred parts by considering a threshold bar amplitude below which the spatial results from the first mode were not considered reliable the sandbars at the six examined sites share common lengths and nondimensional amplitude characteristics which can be described by a negatively skewed gaussian function the absolute amplitude dimensions and the cycle return intervals differ however considerably between the sites the key geometric parameters that steer this intersite variation are the time averaged mean depths at the shoreward and seaward side of the bar zone shore and sea respectively as well as their difference bz the degree to which intersite differences in shore sea and bz are related linearly to intersite differences in bulk statistics of external forcings wave tide sediment and bed profile characteristics is inconclusive

the influence of idealized heterogeneity on wet and dry planetary boundary layers coupled to the land surface abstract this manuscript describes numerical experiments investigating the influence of 2 30 km striplike heterogeneity on wet and dry convective boundary layers coupled to the land surface the striplike heterogeneity is shown to dramatically alter the structure of the convective boundary layer by inducing significant organized circulations that modify turbulent statistics the impact strength and extent of the organized motions depend critically on the scale of the heterogeneity relative to the boundary layer height zi the coupling with the land surface modifies the surface fluxes and hence the circulations resulting in some differences compared to previous studies using fixed surface forcing because of the coupling surface fluxes in the middle of the patches are small compared to the patch edges at large heterogeneity scales zi 18 horizontal surface flux gradients within each patch are strong enough to counter the surface flux gradients between wet and dry patches allowing the formation of

an investigation of the multi scale temporal variability of beach profiles at duck using wavelet packet transforms abstract in an earlier paper a particular discrete wavelet transform dwt was used to study the complex variation of beach profile changes however use of the dwt requires that the sequence of spatial and temporal resolution is fixed as a dyadic sequence which means that the variability over longer intervals is not characterised well here we introduce the discrete wavelet packet transform dwpt that uses an adaptive scaling to partition the data variance according to an entropy cost function the advantages of this approach are demonstrated by its application to the study of temporal variability of a 22 year record of beach profile data from the field research facility frf at duck north carolina usa time series of beach elevations at three locations across a particular profile are investigated in detail we conclude that the dwpt provides a superior analysis of non stationary time series to that of the dwt with improved resolution of the scale intervals of the variability the beach elevation around the shoreline is shown to respond at both sub annual and interannual scales but variability at an annual scale is weak moving seaward into deeper water the variance is partitioned into fewer and longer scales it is confirmed that elevation changes around the inner bar at duck exhibit a strong interannual variation consistent with plant et al plant n g holman r a and freilich m h 1999 a simple model for interannual sandbar behaviour journal of geophysical research 104 c7 15755 15776 around 23 of the variance around the inner bar is explained at the temporal scale of 64 128 months which is consistent with the bar behaviour of 6 years found by ruessink et al ruessink b g wijnberg k m holman r a kuriyama y and van enckevort i m j 2003 intersite comparison of interannual nearshore bar behaviour journal of geophysical research 108 c8 1 12 a significant new finding is however that about 26 of the variance is attributable to temporal scales of 16 21 3 months reconstruction of the wavelet packet components for individual temporal scales is shown to provide a means for identifying the impact and scale of non stationary events such as storms on the beach response this provides further information that can be used to interpret the morphological changes in terms of the forcing processes and also serves to inform morphodynamic modelling

scale invariant characteristics of the storegga slide and implications for large scale submarine mass movements abstract this study documents the fractal characteristics of submarine mass movement statistics and morphology within the storegga slide geomorphometric mapping is used to identify one hundred and fifteen mass movements from within the storegga slide scar and to extract morphological information about their headwalls analyses of this morphological information reveal the occurrence of spatial scale invariance within the storegga slide non cumulative frequency area distribution of mass movements within the storegga slide satisfies an inverse power law with an exponent of 1 52 the headwalls exhibit geometric similarity at a wide range of scales and the lengths of headwalls scale with mass movement areas composite headwalls are self similar one of the explanations of the observed spatial scale invariance is that the storegga slide is a geomorphological system that may exhibit self organized criticality in such a system the input of sediment is in the form of hemipelagic sedimentation and glacial sediment deposition and the output is represented by mass movements that are spatially scale invariant in comparison to subaerial mass movements the aggregate behavior of the storegga slide mass movements is more comparable to that of the theoretical sandpile model the origin of spatial scale invariance may also be linked to the retrogressive nature of the storegga slide the geometric similarity in headwall morphology implies that the slope failure processes are active on a range of scales and that modeling of slope failures and geohazard assessment can extrapolate the properties of small landslides to those of larger landslides within the limits of power law behavior the results also have implications for the morphological classification of submarine mass movements because headwall shape can be used as a proxy for the type of mass movement which can otherwise only be detected with very high resolution acoustic data that are not commonly available

long term fluvial archives in hungary response of the danube and tisza rivers to tectonic movements and climatic changes during the quaternary a review and new synthesis abstract the paper discusses the quaternary evolution of the danube and tisza rivers and their main tributaries in the context of evolution of the entire pannonian basin which is europe s largest intramontane basin within the alp carpathian orogen the palaeo drainage reconstruction of the pannonian basin for the pre quaternary period is outlined in connection with the gradual regression of lake pannon since the late miocene deltas of rivers that entered the basin from the northwest and northeast were gradually transformed into extended alluvial plains thus the earliest possible ancestor of the danube coming southeastwards from the alps could be as old as late miocene by the pliocene the whole lake pannon was infilled the former extensional basin formation was replaced by a compresional stress field which resulted in an uplift of the marginal flanks and late stage subsidence anomalies the increasing relief led to the formation of the quaternary drainage pattern the actively subsiding young basins were filled by fluvial sediments transported by the danube and tisza river systems from the uplifting mountains between the subsiding regions of the little and great plains the danube has formed an antecedent valley with terrace staircases between the uplifting sections of the transdanubian range and the north midmountains the formation of the terraces is attributed to periodic climate changes during the pleistocene combined with differences in the uplift rate the paper gives a complex overview of the classical chronology of the six terraces based on various data sources mostly dating of loess paleosol sequences travertines aeolian sand and tephra strata overlying the fluvial sediments complemented by scattered vertebrate faunal data and archaeological evidence directly from the terrace sediments the quaternary drainage pattern evolution of the great plain with a strong tectonic control is discussed in detail rivers originating from the uplifting marginal areas were drawn towards the subsiding depressions which served as local base level changes in subsidence rates in space and time throughout the quaternary resulted in the evolution of a complex drainage pattern a special emphasis is placed on the late pleistocene holocene development of the middle tisza region and the koros basin where the berettyo koros rivers form an eastern tributary system of the tisza river a comparative evaluation of these two areas is especially relevant as they provide insights into large scale late pleistocene avulsion of the tisza river osl dating complemented with inferred transport directions determined from heavy mineral analysis of fluvial sediments in the koros basin has revealed an ancient large meandering river system that can be identified with the palaeo tisza which was flowing along a tectonically controlled depression during the late pleniglacial successions in the middle tisza region have allowed differentiation between the older channels of the palaeo bodrog river and the sajo hernad alluvial fan and the younger meander belts of the new course of the tisza in the tisza system changes in river style braided to various scales of meandering show correspondence to millennial scale climate changes of the last 25 ka while in the koros basin the effects of tectonics are overprinted onto the regional climatic signals

vegetation responses to rapid warming and to minor climatic fluctuations during the late glacial interstadial gi 1 at gerzensee switzerland abstract high resolution pollen analyses made on the same samples on which the ratios of oxygen isotopes were measured that provided the time scale and a temperature proxy after correlation to northgrip 1 a primary succession the vegetation responded to the rapid rise of temperatures around 14 685 yr bp with a primary succession on a decadal to centennial time scale the succession between ca 15 600 and 13 000 yr bp included 1 1 the replacement of shrub tundra by woodland of juniperus and tree birch around 14 665 yr bp 1 2 the response of juniperus pollen to the shift in oxygen isotopes in less than 20 yr 1 3 a sequence of population increases of hippophae rhamnoides ca 14 600 yr bp salix spp ca 14 600 yr bp betula trees ca 14 480 yr bp populus cf tremula ca 14 300 yr bp and pinus cf sylvestris ca 13 830 yr bp 2 biological processes plants responded to the rapid increase of summer temperatures on all organisational levels 2 1 individuals may have produced more pollen e g juniperus 2 2 populations increased or decreased e g juniperus betula later pinus and 2 3 populations changed their biogeographical range and may show migrational lags 2 4 plant communities changed in their composition because the species pools changed through immigration and local extinction some plant communities may have been without modern analogue these mechanisms require increasing amounts of time 2 5 processes on the level of ecosystems with species interactions may involve various time scales besides competition and facilitation nitrogen fixation is discussed 3 the minor fluctuations of temperature during the late glacial interstadial which are recorded in 18o resulted in only very minor changes in pollen during the aegelsee oscillation older dryas biozone gi 1d and the gerzensee oscillation gi 1b 4 biodiversity the afforestation at the onset of bolling coincided with a gradual increase of taxonomic diversity up to the time of the major pinus expansion

evaluation of depth of closure using data from duck nc usa using 12 years of frequent high precision profiles collected on a wave dominated sandy oceanic beach to 8 m depth the characteristics and interpretation of depth of closure or the seaward limit of significant profile change is critically examined this includes evaluation of the predictive capability of d1 the seaward boundary of the littoral zone as originally defined by hallermeier 1981 hallermeier r j 1981 a profile zonation for seasonal sand beaches from wave climate coastal eng 4 253 277 depth of closure during major erosional events is usually produced by the seaward limit of offshore bar movement following the original recommendation of hallermeier 1981 d1 based on 12 h exceeded wave height and a reference depth of mean low water provides a robust limit to the observations using a 6 cm change criterion empirically the observed depth of closure is 69 of d1 although the scatter is large this scatter is partly controlled by pre event profile shape most particularly bar configuration depth of closure under accretional conditions can also be measured but it is time scale dependent as accretion is a slow steady process d1 underpredicts closure for accretional situations time interval e g annual depth of closure represents the integral effect of erosional and accretional events an important observation of the data is that depth of closure increases with time scale however the full population of time interval observations is not resolved at duck due to the measurement limit 8 m depth as time interval increases from 1 year to 8 years less cases close most non closing time interval cases coincide with the periods influenced by the most energetic wave events however time interval closures are generally deeper than the biggest event closure in the period showing that it represents more than the largest event the frequency distribution of the data suggests that most if not all of these missing data simply represent closures deeper than 8 m depth up to a 4 year time interval d1 t appears to provide a reasonable limit to the quantified observations it is an interesting result that d1 an event based approach might provide a limit to closure over periods up to 4 years as these time interval closures are generally larger than those produced by single storms therefore the general applicability of this result for more complete data sets or on rapidly evolving i e eroding or accreting coasts is uncertain the present data also suggest that on swell dominated coastlines where accretional processes are dominant d1 may underpredict closure suggesting an important limitation to this approach but as sediment would be moving onshore this may not be a practical problem therefore within the limits of the data set hallermeier s 1981 approach is found to define robust estimates of depth of closure particularly for individual erosional events this useful result is expected to find widespread application in coastal geology and engineering

turbulence structure above a vegetation canopy we compare the turbulence statistics of the canopy roughness sublayer rsl and the inertial sublayer isl above in the rsl the turbulence is more coherent and more efficient at transporting momentum and scalars and in most ways resembles a turbulent mixing layer rather than a boundary layer to understand these differences we analyse a large eddy simulation of the flow above and within a vegetation canopy the three dimensional velocity and scalar structure of a characteristic eddy is educed by compositing using local maxima of static pressure at the canopy top as a trigger the characteristic eddy consists of an upstream head down sweep generating hairpin vortex superimposed on a downstream head up ejection generating hairpin the conjunction of the sweep and ejection produces the pressure maximum between the hairpins and this is also the location of a coherent scalar microfront this eddy structure matches that observed in simulations of homogeneous shear flows and channel flows by several workers and also fits with earlier field and wind tunnel measurements in canopy flows it is significantly different from the eddy structure educed over smooth walls by conditional sampling based only on ejections as a trigger the characteristic eddy was also reconstructed by empirical orthogonal function eof analysis when only the dominant sweep generating head down hairpin was recovered prompting a re evaluation of earlier results based on eof analysis of wind tunnel data a phenomenological model is proposed to explain both the structure of the characteristic eddy and the key differences between turbulence in the canopy rsl and the isl above this model suggests a new scaling length that can be used to collapse turbulence moments over vegetation canopies

coherent structures in the boundary and cloud layers role of updrafts subsiding shells and environmental subsidence coherent structures such as updrafts downdrafts shells and environmental subsidence in the boundary and cloud layers of shallow convection are investigated using a new classification method using large eddy simulation data the new method first filters out background turbulence and small scale gravity waves from the coherent part of the flow composed of turbulent coherent structures and large scale transporting gravity waves then the algorithm divides this coherent flow into updrafts downdrafts shells subsidence ascendance and four other flow structures using an octant analysis the novel method can systematically track structures from the cloud free boundary layer to the cloud layer thus allowing systematic analysis of the fate of updrafts and downdrafts the frequency and contribution of the coherent structures to the vertical mass flux and transport of heat and moisture can then be investigated for the first time updrafts subsidence and downdrafts subsiding shells to a lesser extent are shown to be the most frequent and dominant contributors to the vertical transport of heat and moisture in the boundary layer contrary to previous perspective environmental subsidence transport is shown to be weak in the cloud layer instead downdrafts shells are the main downward transport contributors especially in the trade inversion layer the newly developed method in this study can be used to better evaluate the entrainment and detrainment of individual or an ensemble of coherent structures from the unsaturated boundary layer to the cloud layer

fluvial history of the sub carpathian basins poland during the last cold stage 60 8 cal ka bp abstract the fluvial landforms of the last cold stage are represented in the sub carpathian basins by a system of 2 3 terraces which grade into alluvial fans of a height of 15 20 8 12 and 6 8 m above the present riverbeds in the mountain foreland in the vistula river valley the 15 20 m high terrace covered with loess extends along the western margin of the sandomierz basin and northern margin of the carpathians away from the mountain margin it passes into the sandy terrace plain with dunes it is formed of at least two interpleniglacial alluvial fills the older one dated at 48 36 ka bp over 50 40 6 ka cal bp and the younger one dated 30 25 ka bp 34 1 29 0 ka cal bp thus pertaining to the upper pleniglacial this latter forms a terrace 15 m high in general accumulation of fluvial sediments interrupted with erosion phases dominated in the mountain foreland during the period 60 25 ka bp over 60 29 ka cal bp the most significant erosion phase took place before the maximum extension of the vistulian weichselian wisconsinian ice sheet i e before 25 20 ka bp 29 24 ka cal bp and was connected with a change from an oceanic to a more continental climate the next alluvial fill of terrace 8 12 m high with remnants of braided river channels was formed at the end of the upper plenivistulian the incision of the river channels below the present channel level was followed by aggradation in the late vistulian 15 13 ka bp 18 2 15 6 ka cal bp accompanied by a change in river channel system from braided to meandering in the wisloka and san river valleys alluvial plains extending by lateral erosion of large meanders were abandoned by rivers mainly in the younger dryas and the preboreal the late vistulian large palaeomeanders are missing along lower sola and lower dunajec these rivers fed from higher mountains had still tendency to braiding the climate cooling of the younger dryas brought an increase in the delivery of bedload to the river channels and a tendency to braiding in vistula valley drwinka depression the expansion of forest in the early holocene reduced the water discharge and the size of meanders as a result their width fallen by 3 5 times alluvial data showed also a distinct humid climatic phase ca 9 5 8 5 ka cal bp

divergent response of an intertidal swash bar this paper examines the processes responsible for the morphodynamics of an intertidal swash bar at skallingen denmark during seven successive storms one with a large surge of 3 02 m dnn during this period a subtidal bar migrated landward onto the foreshore and continued to migrate across the intertidal zone as a swash bar the onshore migration of the inner subtidal bar resulted from the erosion of sediment from the upper foreshore and dune ramp during the large storm surge that was transported seaward causing the landward displacement of the bar through accretion on the landward slope the magnitude and direction of suspended sediment transport within the intertidal zone and more specifically at and close to the crest of the swash bar varied with the ratio of both the significant hs and average havg wave heights to the water depth hcr at the swash bar crest the local depth minimum the transition between onshore and offshore suspended sediment transport was associated with the average wave of the incident distribution breaking on the swash bar crest havgh 0 33 while the onshore directed transport was largest at infragravity frequencies sediment resuspension was best explained by the skewed accelerations under the surf bores offshore transport was dominated by the cross shore mean currents undertow that developed when the significant wave of the distribution broke on the swash bar crest hsh 0 33 and weakened as the average wave of the distribution started to break at the crest havgh 0 33 and the surf zone approached saturation in contrast to subtidal bars the swash bar at skallingen exhibited a divergent behaviour with respect to the cross shore position of the breaker zone migrating onshore when the average wave broke seaward of the crest and migrating offshore when the average wave broke landward of the crest copyright 2006 john wiley sons ltd

reflection of the glacial interglacial cycle in the evolution of the vistula river basin poland a variety of factors has controlled the evolution of the vistula river valley they include climatically induced changes of the river runoff and sediment load glacial advances and rapid variations of the base level as well as the influence of the tectonic factor the first order climatic cycles are reflected in separate terrace fills the second order fluctuations may be represented by separate cuts and fills by the change of the facies or by the change in the granulometric composition the analysis of the changes in the longitudinal profile helped to discover a great variety of different valley reaches and a general tendency to smooth the long profile during the quaternary

the younger dryas cold interval as viewed from central greenland abstract greenland ice core records provide an exceptionally clear picture of many aspects of abrupt climate changes and particularly of those associated with the younger dryas event as reviewed here well preserved annual layers can be counted confidently with only 1 errors for the age of the end of the younger dryas 11 500 years before present ice flow corrections allow reconstruction of snow accumulation rates over tens of thousands of years with little additional uncertainty glaciochemical and particulate data record atmospheric loading changes with little uncertainty introduced by changes in snow accumulation confident paleothermometry is provided by site specific calibrations using ice isotopic ratios borehole temperatures and gas isotopic ratios near simultaneous changes in ice core paleoclimatic indicators of local regional and more widespread climate conditions demonstrate that much of the earth experienced abrupt climate changes synchronous with greenland within thirty years or less post younger dryas changes have not duplicated the size extent and rapidity of these paleoclimatic changes

channel hydrodynamics of submerged flexible vegetation with seepage abstractthe presence of aquatic vegetation changes the flow characteristics in a channel the impact of the presence of submerged flexible vegetation in a channel with an additional parameter such as downward seepage is analyzed in the present work two patterns staggered and uniform and two different vegetation spacing 15 and 10 cm center center were adopted experiments were conducted for the case of no seepage 10 seepage and 15 seepage velocity profiles show the presence of an inflection point near the top of the vegetation where maximum reynolds stress is achieved the velocity profiles measured in the unobstructed region of uniform pattern are higher compared to the velocity measured in line with the vegetation stems downward seepage increases the velocity reynolds stress and turbulent intensities in the average range of 10 15 as compared to the no seepage case higher order turbulent statistics such as moment analysis quadrant analysis and turbulent kinetic budget are derived through

environmental changes at the younger dryas preboreal transition and during the early holocene some distinctive aspects in central europe data on environmental change at the younger dryas preboreal transition and during the early holocene are reviewed with particular reference to evidence from poland and neighbouring areas of central europe various factors modified the rate of environmental change during the general warming and reforestation the preservation in central europe of coniferous forest at the beginning of the holocene and the relatively late development of deciduous forest were connected with the continuation of a continental climate until 9000 8500 bp this is the main cause for a distinct division of the early holocene into three phases 1 10 300 9500 bp rapid warming 2 preboreal boreal continuous transformation 10 000 8500 bp 3 change to oceanic climate 8700 7700 bp during the eoholocene period the various environmental systems such as biological aeolian fluvial and lacustrine exhibited diachronous evolution with different rates of change the distinctive changes in central europe are contrasted with other re

the importance of independent chronology in integrating records of past climate change for the 60 8 ka intimate time interval this paper provides a brief overview of the most common dating techniques applied in palaeoclimate and palaeoenvironmental studies including four radiometric and isotopic dating methods radiocarbon 230th disequilibrium luminescence cosmogenic nuclides and two incremental methods based on layer counting ice layer varves for each method concise background information about the fundamental principles and methodological approaches is provided we concentrate on the time interval of focus for the intimate integrating ice core marine and terrestrial records community 60 8 ka this dating guide addresses palaeoclimatologists who aim at interpretation of their often regional and local proxy time series in a wider spatial context and therefore have to rely on correlation with proxy records obtained from different archives from various regions for this reason we especially emphasise scientific approaches for harmonising chronologies for sophisticated and robust proxy data integration in this respect up to date age modelling techniques are presented as well as tools for linking records by age equivalence including tephrochronology cosmogenic 10be and palaeomagnetic variations finally to avoid inadequate documentation of chronologies and assure reliable correlation of proxy time series this paper provides recommendations for minimum standards of uncertainty and age datum reporting

earthquakes as self organized critical phenomena a cellular automation model with threshold elements previously proposed by bak et al 1988 which generates 1 f noise and self organizes into a critical state is studied as a model for earthquake occurrence the model explains some of fractal features of earthquakes such as the power law distribution of the size of the earthquake the model is modified so that every earthquake may trigger aftershocks the modified trigger model explains other fractal features of earthquakes such as the power law decay of aftershock frequency and the power law decay of aftershock frequency and the power law correlation of the hypocenter distribution

young danube delta documents stable black sea level since the middle holocene morphodynamic paleogeographic and archaeological implications new radiocarbon and optical dates show that the holocene danube delta started to build out of a black sea embayment 5200 yr ago delta lobe development phases differ by as much as 5 k y from previously proposed ages the new chronology allows for a better understanding of the danube delta paleogeography includ ing the demise of istria the main ancient greek roman city in the region prior reconstructions of sea level in the black sea inferred fluctuations to 15 m in range however stratigraphy of beach ridg es in the delta shows that the relative black sea level for the past 5 k y was stable in the danube delta region within 2 m and 1 5 of the current level hydroisostatic effects related to a proposed catastrophic reconnection of the black sea to the world ocean in the early holocene may have been responsible for the sea level reaching the highstand earlier than estimated by models the new sea level data suggest that submergence at several ancient settle ments around the black sea may be better explained by local fac tors such as subsidence rather than by basin wide sea level fluctuations

temporal and spatial scales of beach profile change duck north carolina abstract an 11 year time series of high resolution beach profile surveys made on an atlantic ocean beach was analyzed for spatial and temporal characteristics of beach profile change approximately 300 profile surveys most extending from the dune to 8 m depth were available for the analysis on each of four cross shore lines together with electronically recorded and statistically processed wave time series from a nearshore gage located seaward of the survey site the profile survey data set was analyzed for such quantities as depth change frequency of depth change general seasonal shape of the profile seasonal depth change and change in the profile produced by extreme storms the morphodynamics of an inner and outer longshore bar were also examined including depth to bar crest bar height and length and speed of bar movement onshore and offshore several properties of depth change were related to wave characteristics representative results were average profile elevation change from 4 m to 4 m was symmetric about the mean sea level shoreline the average spring and autumn profile shapes were almost identical and occurred as transitional states between the summer and winter profile shapes the depth of active profile movement within survey accuracy of about 0 025 m was 4 m for the summer and 6 m for the winter and the 10 year frequencies of maximum absolute depth change in depths of 2 4 6 and 8 m were 1 64 1 38 0 22 and 0 12 m respectively a surprising result was that typical large storms transported sand into the nearshore from the seaward end of the profile from a depth of about 6 8 m

interaction between turbulent flow and sea breeze front over urban like coast in large eddy simulation turbulent flow and its interaction with a sea breeze front sbf over an urban like coast with a regular block array were investigated using a building resolving computational fluid dynamics model it was found that during daytime with an offshore ambient flow streaky turbulent structures tended to grow within the convective boundary layer cbl over a warm urban surface ahead of the sbf the structures were organized as streamwise streaks at an interval of a few hundred meters which initiated at the rooftop level with strong wind shear and strengthens in the cbl with moderate buoyancy the streaks then interacted with the onshore propagating sbf as it made landfall the sbf which was initially characterized as a shallow and quasi linear feature over the sea developed three dimensional structures with intensified updrafts at an elevated frontal head after landfall frontal updrafts were locally enhanced at intersections where the streaks merged with the sbf which greatly increased turbulent fluxes at the front the frontal line was irregular because of merging tilting and transformation effects of vorticity associated with streaky structures inland penetration of the sbf was slowed by the frictional effect of urban like surfaces and turbulent flow on land the overall sbf intensity weakened after the interaction with turbulent flow these findings aid understanding of local weather over coastal cities during typical sea breeze conditions

turbulent reynolds stress and quadrant event activity in wind flow over a coastal foredune recent research on quasi instantaneous turbulent kinematic reynolds stresses rs u w and decomposed quadrant event activity e g ejections and sweeps over dunes in fluvial settings and in wind tunnels has shown that turbulent stresses at the toe of a dune often exceed time averaged streamwise shear stress u 2 estimates it is believed that semi coherent turbulent structures are conveyed toward the bed along concave streamlines in this region and that impact of these structures cause fluctuations in local surface stresses that assist in grain entrainment this has been hypothesized to explain how sand is supplied to the windward slope through a region of flow stagnation toward the crest surface stress increases and becomes dominated by streamwise accelerations resulting from streamline compression and convexity that suppress vertical motions high frequency 32 hz measurements of turbulent wind flow from 3 d ultrasonic anemometers are analyzed for oblique onshore flow over a vegetated coastal foredune in prince edward island canada reynolds stress and quadrant activity distributions varied with height 0 60 m and 1 66 m and location over the dune in general quadrant 2 ejection u 0 and quadrant 4 sweep activity u 0 w 0 w 0 and quadrant 3 inward interaction u 0 w 0 activity on the lower stoss slope significant ejection and sweep event activity was most frequent 85 to 92 ejections plus sweeps whereas at the upper crest significant ejection and sweep activity became less frequent while significant outward and inward interactions increased in frequency 25 to 36 an exuberance effect i e changing shape of quadrant frequency distribution skewed toward ejection and sweep activity is observed whereby streamline compression and convexity effects inhibit vertical fluctuations in flow and thus reduce the frequency of ejections and sweep activity toward the crest in separated flow in the lee of the crest quadrant distributions were more symmetrical as a result of more mixed multi directional flow these trends in turbulent event distributions and reynolds stress have implications for sediment transport dynamics across the dune and may help to explain sand transport potential and dune maintenance for example areas with a high frequency of ejection and sweep activity may have higher rates of sediment entrainment and transport whereas areas with lower ejection and sweep activity and an increase in outward and inward interactions which contribute negatively to reynolds stress generation may experience a greater potential for deposition further research on associations between quadrant event activity and coincident sand transport is required to confirm this hypothesis and the resultant significance of the flow exuberance effect in aeolian dune morphodynamics

waving plants and turbulent eddies new large eddy simulations of flow over a flexible plant canopy by dupont et al j fluid mech 2010 this issue vol 652 pp 5 44 have produced apparently paradoxical results work over the last three decades had suggested that turbulent eddies could lock onto to the waving frequency of uniform cereal canopies their new simulations contradict this view although a resolution may lie in the essentially three dimensional nature of the instability process that generates the dominant eddies above plant canopies

last glacial interglacial cycle in the evolution of river valleys in southern and central poland abstract the last glacial interglacial cycle is represented usually by several cuts and fills which have formed 2 3 terrace steps from the last cold stage and by two or more fills of lateglacial holocene age their number depends on the size of the river valley and the position in the longitudinal profile the sequence of changes reflects shorter stadial interstadial climatic fluctuations generally aggradation dominates during the cooler phases of the vistulian and during the interpleniglacial the most distinct erosional phases occurred during the change from a more oceanic to a more continental climate before the maximum extension of the ice sheet 25 20 ka bp and during the upper pleniglacial lateglacial transition 15 13 ka bp the second phase coincides with the rapid downcutting in the lower course of the main vistula valley which had been blocked earlier by the scandinavian ice sheet in the holocene aggradation prevailed accelerated by anthropogenic soil erosion it was only in the mountain foreland that shorter lived hydrological changes resulted in well expressed several cuts and fills

timing of environmental changes of the weichselian decline 18 0 11 5 ka cal bp using frequency distribution of 14c dates for the łodź region central poland abstract in the study a statistical approach for environmental reconstruction has been undertaken based on the set of radiocarbon dates from the old morainic area of central poland the od region the probability density function pdf was constructed the shape of the pdf reflects an alternation of warmer and cooler phases and casts light on the duration and pace of changes in the environment of the weichselian decline 18 0 11 5 ka cal bp by comparing the peaks and falls of the pdf with the results of comprehensive palaeogeographical investigations of the area of the analysed time interval three phase development of the od region has been distinguished 1st stage older than ca 14 2 ka cal bp 2nd stage from ca 14 2 to ca 12 6 ka cal bp and 3rd stage from ca 12 6 ka cal bp a contribution to the knowledge of the palaeogeography of the region is the recognition in the record of the cold inter allerod period and the confirmation of a warming in the region at ca 18 ka cal bp

hydrodynamics and sediment transport within the inner surf zone of a lacustrine multiple barred nearshore abstract it has become increasingly recognized that the typically unexpected behavior of the nearshore profile over a sequence of storm events is a response to strong feedback between the antecedent morphology and the incident wave field this paper systematically examines the suspended sediment transport and morphodynamics within the surf zone of a lacustrine multiple barred upper shoreface a range of significant wave heights h s and local relative wave heights h s h 1 h water depth are considered in order to describe and identify the limits to the feedback mechanisms that can dominate the nearshore response data from collocated concentration and velocity sensors indicate that the direction and magnitude of suspended sediment transport varies with the degree of local wave energy dissipation and the cross shore variation in these relationships depends partly on the local bed slope this dependence indicates the presence of a strong self organization at the scale of the individual bar within the inner surf zone these bar scale relationships are constrained by the shoaling transformations which occur over the outermost bar for ranges of incident wave height defined locally e g intermediate waves h s 0 4 to 0 9 m storm waves 0 9 to 1 4 m the innermost and middle bars remain in a state of self organized equilibrium for intermediate range waves this equilibrium is a consequence of wave height reduction over the outer bar through breaking and the generation of secondary harmonic waves for the storm wave range the equilibrium is maintained through a resonant amplification of discrete edge wave modes with the bars forced to a position coincident with the surface elevation antinodes these upper shoreface scale feedback mechanisms are weakened particularly for intermediate wave heights following threshold storms capable of moving the outermost bar offshore and lower on the profile this allows the middle and inner bars to be forced directly by variations in the offshore incident waves thus the bars respond in a cyclic manner the bar cycle

correlation and synchronisation of lateglacial continental sequences in northern central europe based on annually laminated lacustrine sediments abstract the present study focusses on correlation and synchronisation of weichselian lateglacial varved lake sediments from western germany meerfelder maar eifel region northern germany hamelsee lower saxony central poland lake go ci a z and eastern poland lake perespilno by using varve chronology tephrochronology palynostratigraphy and stable isotopes comparison of the several independent time scales shows that biotic and abiotic parameters respond abruptly and quasi synchronously within the errors of the different chronologies during the younger dryas preboreal transition moreover there is a consensus about the length of the younger dryas cold stage of 1100 1150 varve years in the allerod the prominent laacher see tephra 12 880 varve years bp can be used to fix floating varve chronologies the relative duration of this biozone has been determined in meerfelder maar and hamelsee at between 625 and 670 varve years in the meerfelder maar a combination of continuous varve counting and biostratigraphy has been possible for the almost entire lateglacial the comparison between continental limnic sequences and greenland ice core records should be made on the basis of independent chronologies in both archives it is more practicable to develop regional stratotypes on the continental regions instead of simply using ice cores as stratotypes for the lateglacial for terrestrial european records in this respect annually laminated lacustrine sequences have a great potential

the full glacial forests of central and southeastern europe the presence of trees in central and southern europe during the last full glaciation has long been a matter of debate a low but persistent presence of fossil tree pollen in central and southern european full glacial paleoecological sequences has been interpreted either as representing long distance pollen transport from southerly refuges or as representing in situ refugial populations here we present macroscopic charcoal results from 31 sequences located throughout hungary that provide unequivocal evidence for the presence of at least seven different tree types between approximately 32 500 and 16 500 14c yr b p this evidence is presented in conjunction with molluscan and pollen analyses to indicate that during the last full glaciation trees grew as far north as hungary probably in microenvironmentally favorable sites these areas provided an important cold stage refugium for the european flora and fauna

numerical predictability experiments of cross shore sandbar migration 1 surf zone sandbars common features along the world s sandy coastlines continuously change their position in response to time variable offshore wave conditions process based predictions of cross shore sandbar migration relevant to the understanding of autonomous and artificially altered evolution of beaches are intrinsically imprecise because of uncertainty in the model equations and potentially the sensitive dependence on the initial bathymetry however the magnitude of the resulting predictability limit and its dominant source are unknown here we show that cross shore sandbar migration on the time scale of years is deterministically forced rather than deterministically chaotic and that the unpredictability of sandbar migration results primarily from model inadequacy during major wave events because the unpredictability of sandbar migration is related to the stochastic nature of the forcing the predictability limit is not a fixed value but depends on the timing of the wave event we anticipate that detailed experiments to understand nearshore evolution from the underlying first principles will eventually pay off by extending the range of plausible simulated behavior and consequently will increase our ability to understand and predict how coasts may respond to changing climate

review of wave turbulence interactions in the stable atmospheric boundary layer flow in a stably stratified environment is characterized by anisotropic and intermittent turbulence and wavelike motions of varying amplitudes and periods understanding turbulence intermittency and wave turbulence interactions in a stably stratified flow remains a challenging issue in geosciences including planetary atmospheres and oceans the stable atmospheric boundary layer sabl commonly occurs when the ground surface is cooled by longwave radiation emission such as at night over land surfaces or even daytime over snow and ice surfaces and when warm air is advected over cold surfaces intermittent turbulence intensification in the sabl impacts human activities and weather variability yet it cannot be generated in state of the art numerical forecast models this failure is mainly due to a lack of understanding of the physical mechanisms for seemingly random turbulence generation in a stably stratified flow in which wave turbulence interaction is a potential mechanism for turbulence intermittency a workshop on wave turbulence interactions in the sabl addressed the current understanding and challenges of wave turbulence interactions and the role of wavelike motions in contributing to anisotropic and intermittent turbulence from the perspectives of theory observations and numerical parameterization there have been a number of reviews on waves and a few on turbulence in stably stratified flows but not much on wave turbulence interactions this review focuses on the nocturnal sabl however the discussions here on intermittent turbulence and wave turbulence interactions in stably stratified flows underscore important issues in stably stratified geophysical dynamics in general

climatic reconstruction of the weichselian pleniglacial in northwestern and central europe a multiproxy approach is applied to reconstructing accurately the weichselian pleniglacial climate 72 13 ka in northwestern and central europe standardised translations are used to transform proxy data into climate parameter values for six characteristic time windows quantitative reconstructions of the temperature regime are derived from periglacial coleoptera and botanical evidence while aeolian and fluvial evidence provide qualitative information on wind activity and precipitation respectively the early pleniglacial 74 59 ka the cold period between 41 38 ka and the late pleniglacial 27 13 ka are characterised by a strong north to south climatic gradient over northwestern europe during the last glacial maximum discontinuous permafrost was established in northern france whereas the continuous permafrost zone extended from the uk belgium the netherlands germany and poland to the nordic ice sheets prominent wind activity and a relatively low precipitation typify these periods in contrast an indistinct west to east climate gradient was present in the relatively more temperate intervals e g 50 41 ka seasonally frozen ground conditions prevailed in northwestern europe whereas discontinuous permafrost may be suggested for central germany it appears that the climate conditions in northwest and central europe were controlled by three major factors the scandinavian ice sheet the north atlantic surface water circulation and the russian continent 1998 john wiley sons ltd

coastal profile evolution at duck north carolina a cautionary note the hurst exponents of 10 8 year long time series of cumulative bed level observed between the shoreline and 8 m water depth on an ocean beach are shown to be consistent with bed level time series described by a sinusoid with a 10 8 year period plus white noise thus for these observations hurst exponents cannot distinguish self organized morphological evolution from the hypothesis that nearshore morphology on monthly to decadal timescales is a forced response to small scale physical processes driven by waves and currents

chaos fractals and self organization in coastal geomorphology simulating dune landscapes in vegetated environments complex nonlinear dynamic systems are ubiquitous in the landscapes and phenomena studied by earth sciences in general and by geomorphology in particular concepts of chaos fractals and self organization originating from research in nonlinear dynamics have proven to be powerful approaches to understanding and modeling the evolution and characteristics of a wide variety of landscapes and bedforms this paper presents a brief survey of the fundamental ideas and terminology underlying these types of investigations covering such concepts as strange attractors fractal dimensions and self organized criticality their application in many areas of geomorphological research is subsequently reviewed in river network modeling and in surface analysis amongst others followed by more detailed descriptions of the use of chaos theory fractals and self organization in coastal geomorphology in particular these include self organized behavior of beach morphology the fractal nature of ocean surface gravity waves the self organization of beach cusps and simulation models of ripples and dune patterns this paper further presents a substantial extension of existing dune landscape simulation models by incorporating vegetation in the algorithm enabling more realistic investigations into the self organization of coastal dune systems interactions between vegetation and the sand transport process in the model such as the modification of erosion and deposition rules and the growth response of vegetation to burial and erosion introduce additional nonlinear feedback mechanisms that affect the course of selforganization of the simulated landscape exploratory modeling efforts show tantalizing results of how vegetation dynamics have a decisive impact on the emerging morphology and conversely how the developing landscape affects vegetation patterns extended interpretation of the modeling results in terms of attractors is hampered however by want of suitable state variables for characterizing vegetated landscapes with respect to both morphology and vegetation patterns d 2002 elsevier science b v all rights reserved

holocene forest dynamics in northwestern romnania pollen analyses and ams radiocarbon measurements were carried out on peat deposits from the former crater lake preluca tiganului located in a mid altitude area of the gutaiului mountains nw romania in order to reconstruct the postglacial vegetation history at the lateglacial holocene transition the open vegetation was replaced by forest suggesting a fast response to climatic warming the rapid expansion of pinus betula and later picea may be due to their existence in the area during the lateglacial at approximately 11 250 cal yr bp the dense forest was composed primarily of ulmus and some picea betula and pinus a small population of ulmus might also have survived in the area during the lateglacial at 10750 cal yr bp quercus tilia and fraxinus followed by corylus at c 10200 cal yr bp expanded significantly in the forest the delay of approximately 550 years in their establishment as compared to the expansion of ulmus was probably due to their immigration from more distant localities

palaeohydrology of the seim river basin mid russian upland based on palaeochannel morphology and palynological data abstract morphological geological geochronological and palynological analyses show that the landscape climate and hydrological history of the seim river basin includes 1 a period of sandy terrace 1 formation by shallow flows with the surface transformation by cryogenic and aeolian processes close to the last glaciation maximum 2 a cold and dry period about 16 14 k radiocarbon years b p with very high surface runoff and extremely large meandering channel formation 3 a period between the oldest dryas and the preboreal of non steady surface runoff decrease large meander abandonment and formation of smaller channels against the background of climate warming 4 a period of relative stability of hydrological regime and small variations of water runoff as in modern rivers throughout the holocene

late quaternary paleodrainage reconstruction of the maros river alluvial fan abstract the surface of the extensive maros alluvial fan is densely 0 78 km km 2 covered by paleochannels the aim of the present study is to reconstruct the final late quaternary stage of the alluvial fan development by identifying paleodrainage directions and determining morphology and pattern of the paleochannels and the age of their activity on the surface of the alluvial fan 18 meandering braided anastomosing or misfit paleochannel zones were identified the existence of these channels indicates that the main process of the fan development was avulsion rather than lateral channel shift and the overbank floodplain accumulation played a minor role as the paleochannels were not buried the oldest paleodrainages a c shifted towards north from the east west axis of the alluvial fan draining water to the koros basin the similar age 18 7 2 3 ka 14 2 1 4 ka of the paleochannel zones indicates rapid avulsions or the coexistence of paleodrainages in the northern half of the alluvial fan the last large d paleodrainage change occurred 12 4 2 1 ka when the channel turned westward a large meandering channel functioned for a period 12 4 2 1 ka 9 6 1 3 ka and with the coexisting misfit channels these channels drained a considerable amount of water q b 2500 m 3 s in the next development phase e paleodrainages the maros flowed north but after a sharp bend it turned toward the south and it started to form the southern lobe of the alluvial fan these channels existed between 8 5 0 9 ka and 3 5 0 4 ka and had a bankfull discharge of 1000 2000 m 3 s the last f paleodrainage of the maros river existed for a short time 1 9 0 3 ka 1 6 0 3 ka and indicated decreasing discharge q b 1400 m 3 s in the final phase of the alluvial fan evolution the present day course of the river was developed and its discharge decreased further 680 m 3 s

the spatial and temporal variability of sand bar morphology the spatial and temporal variability of nearshore sand bar morphology is quantified using a unique data set spanning 2 years the data consist of daily time exposure images of incident wave breaking on an open coast sandy beach which may be used to infer bar morphology lippmann and holman 1989 the morphology in each image is classified into an eight state morphologic scheme in which bars are uniquely defined by four independent criteria the most frequently observed morphologies are the longshore periodic rhythmic bars observed in 68 of the data linear bars occur under highest wave conditions h s 1 78 m and are unstable mean residence time 2 days shore attached rhythmic bars are the most stable mean residence time 11 days and generally form 5 16 days following peak wave events non rhythmic three dimensional bars are very transient mean residence time 3 days eighty seven percent of transitions to lower bar types defined in text occurred one state at a time supporting our selection of the ordering of states and suggesting the suitability of a sequential morphology model transitions to higher states occurred under rising wave energy and were evenly spread among the possible higher states with more substantial changes in morphology resulting from larger wave increases this suggests that up state erosional transitions based on offshore bar migration are better described by an equilibrium model where response is better correlated with incident wave energy than with preceding morphological state time exposure images were also digitized to yield quantitative estimates of bar crest location as a function of longshore distance principal component analysis was used to decompose bar position into two dimensional linear and three dimensional longshore variable components cross shore linear bar position ranges 50 m about the 2 year mean 27 m standard deviation and dominates bar variability 74 6 three dimensional bar structure accounts for 14 of the variance 12 m standard deviation changes in incident wave height precede cross shore bar migration by less than 1 day changes in longshore variability are inversely correlated to changing wave conditions with bar morphology becoming linear rapidly during storms on time scales of less than 1 day evolution to significantly three dimensional structure typically occurs over 5 7 days following peak wave events

multi scale variability of beach profiles at duck a wavelet analysis beach profiles have been observed to change over a range of spatial and temporal scales however techniques for quantifying this variability have not been fully established in this paper a wavelet technique is introduced as a method to study the multi scale variability of beach profiles the beach profile data comprising a 22 year time series surveyed at the us army corps of civil engineers field research facility frf at duck are analysed using the adapted maximal overlap discrete wavelet transform amodwt the analysis successfully identifies strong local features in the variability of beach profiles in time and space separately that cannot be isolated by traditional statistical methods the analysis of spatial wavelet variances provides a new means of investigating the depth of closure analysis of variances by temporal scales shows that the combined effects of several temporal scales with one or two dominant scales can be seen at particular points across profiles whilst the dominant temporal scales are different at different portions of the profiles the method allows for the extremely nonstationary behaviour of beach profile to be analysed into separate frequency bands that can facilitate the interpretation of morphological changes in terms of physical processes

regularity and randomness in the formation of beach cusps abstract controversy still exists on whether rhythmic features such as beach cusps are the result of the presence of standing edge wave motions in the hydrodynamics or if they are the result of self organising processes the compatibility between the two mechanisms is here investigated through the use of a numerical model simulating the formation and development of beach cusps simulations characterised by different forcing conditions have been performed a series of random simulations each individual run simply differing from the others in the seed used in the random number generator showed the typical self organisation behaviour with the features appearing at different locations and even with slightly different spacing regular series of simulations have been run by changing the wavelength of the template superimposed by the hydrodynamic forcing and the number of cycles when the template was present results surprisingly indicate that even a minimum number of cycles with a regular forcing can deterministically induce the final shoreline configuration furthermore if the forcing template has the same wavelength as the one resulting from purely random simulations growth rates are much faster than those obtained with random conditions implications for the kind of field measurements necessary to discern which of the two mechanisms is responsible for beach cusp formation have also been considered

storm driven variability of the beach nearshore profile at duck north carolina usa 1981 1991 the us army corps of engineers field research facility frf at duck north carolina has collected approximately biweekly beach nearshore profile data to 8 m depth and associated wave data since 1981 sediment budget analysis was used to examine the medium scale years to a decade variability of the beach nearshore profile from 1981 to 1991 significant changes occurred during four groups of energetic storm events during february march of 1983 1987 1989 and december 1989 each group was comprised of at least two storms within a period of less than 39 days both with hmo 4 m during each storm group offshore sediment movement caused a distinct outer bar to migrate offshore and grow in size resulting in an abrupt increase in the volume of sediment on the upper shoreface the net profile changes were much larger than the changes due to single storms and the cumulative effect of the storms can be considered as one event during these events the first storm appears to have a destabilizing effect on the profile which has insufficient time to recover before the second and subsequent storm s as a result several storms in quick succession are able to have a large impact on the morphology the intervening periods between the groups of storm events termed fairweather conditions lasted up to 4 years they are characterized by slow but steady sediment redistribution averaging 33 m3 m 1 year 1 from the upper shoreface 5 m depth toward the shore while the total sediment volume was effectively constant the onshore feed of sediment was not significantly affected by individual storms during the fairweather conditions these two processes of 1 morphologic change during groups of storm events and 2 the steady onshore feed of sediments from the shoreface during fairweather conditions appear to play an important role on medium and long term profile evolution at least at duck

past hydrological events reflected in the holocene fluvial record of europe abstract a comprehensive database of radiocarbon dated fluvial units in great britain poland and spain has been compiled to investigate the relationship between environmental change flooding and holocene river dynamics following the methodology recently developed by macklin and lewin macklin m g lewin j 2003 river sediments great floods and centennial scale holocene climate change journal of quaternary science 18 101 105 radiocarbon dates in fluvial sequences that coincide with a modification in sedimentation rate or style have been highlighted allowing geomorphologically significant changes in holocene river activity to be identified data analysis has been undertaken at both national and sub national scales and on catchments of different size type and land use history multiple phases of higher flood frequency characterized by accelerated erosion and sediment deposition on floodplains are recognized and compared with a range of climate proxies the relative and varying roles of climate and land use on river dynamics are considered and the value of the database for reconstructing past hydrological events as well as for predicting river response to future environmental change is assessed

beach cusps as self organized patterns computer simulations of flow and sediment transport in the swash zone on a beach demonstrate that a model that couples local flow acceleration and alongshore surface gradient is sufficient to produce uniformly spaced beach cusps the characteristics of the simulated cusps and the conditions under which they form are in reasonable agreement with observations of natural cusps the self organization mechanism in the model is incompatible with an accepted model in which standing alongshore waves drive the regular pattern of erosion and deposition that gives rise to beach cusps because the models make similar predictions it is concluded that currently available observational data are insufficient for discrimination between them

the effects of wave chronology on medium and long term coastal morphology the sequencing or chronology of wave events plays an important role in determining how coastlines and nearshore regions evolve over medium and long timescales from weeks to decades however present day computer models of coastal morphology treat the input wave conditions in either a deterministic i e a single wave sequence or a probabilistic manner in neither method are the effects of the full range of possible future wave sequences for given overall statistical values calculated the methodology presented here addresses this problem by multiple model runs using different re orderings of a wave sequence a series of tests demonstrate different aspects of wave chronology and its importance in the prediction of seabed and beach levels the method provides a means both for understanding wave chronology effects and for predicting these effects in practical engineering problems involving medium and long timescale changes to coastal morphology

secondary currents and very large scale motions in open channel flow over streamwise ridges it is widely acknowledged that streamwise ridges on the bed of open channel flows generate secondary currents scs a recent discovery of meandering long streamwise counter rotating vortices in open channel flows known as very large scale motions vlsms raises a question regarding the interrelations between vlsms and scs in flows over ridge covered fully rough beds to address it we conducted long duration experiments using stereoscopic particle image velocimetry covering a range of ridge spacings s from approx 0 4 to approx 4 flow depths h for a benchmark no ridge case the flow is quasi two dimensional in the central part of the channel exhibiting a strong spectral signature of vlsms as expected with ridges on the bed at s lessapprox 2h two sc cells are formed between neighbouring ridges and vlsms are entirely suppressed suggesting that ridge induced scs prevent the formation of vlsms by absorbing their energy or overpowering their formation at the same time velocity auto and cross spectra reveal a new feature that can be explained by low amplitude meandering of the alternating low and high momentum flow regions associated with instantaneous manifestations of scs two point velocity correlations and smooth velocity field reconstructions using proper orthogonal decomposition further support the validity of this effect its origin is probably due to the instability related to the presence of inflection points in the spanwise distribution of the streamwise velocity within the sc cells these results have implications for bed friction in open channels where the friction factor may increase if depth scale scs are present or decrease under conditions of sub depth scale scs and suppressed vlsms

storms and shoreline retreat in the southern gulf of st lawrence abstract storms play a major role in shoreline recession on transgressive coasts in the southern gulf of st lawrence gsl southeastern canada long term relative sea level rise off the north shore of prince edward island has averaged 0 3 m century over the past 6000 years 0 2 m century over 2000 years this has driven long term coastal retreat at mean rates 0 5 m a but the variance and details of coastal profile response remain poorly understood despite extensive sandy shores sediment supply is limited and sand is transferred landward into multidecadal to century scale storage in coastal dunes barrier washover deposits and flood tidal delta sinks charlottetown tide gauge records show mean relative sea level rise of 3 2 mm a 0 32 m century since 1911 a further rise of 0 7 0 4 m is projected over the next 100 years when differenced from tidal predictions the water level data provide a 90 year record of storm surge occurrence combined with wind wave hindcast and sea ice data this provides a catalogue of potentially significant coastal storms we also document coastal impacts from three recent storms of great severity in january and october 2000 and november 2001 digital photogrammetry 1935 1990 and shore zone surveys 1989 2001 show large spatial and temporal variance in coastal recession rates weakly correlated with the storm record in part because of wave suppression or coastal protection by sea ice large storms cause rapid erosion from which recovery depends in part on local sand supply but barrier volume may be conserved by washover deposition barrier shores with dunes show high longshore and interdecadal variance with extensive multidecadal healing of former inlet and overwash gaps this reflects recovery from an episode of widespread overwash prior to 1935 possibly initiated by intense storms or groups of storms in the latter half of the 19th century with evidence from the storms of 2000 2001 this points to the importance of storm clustering on scales of weeks to years in determining erosion vulnerability as well as the need for a long term large scale perspective in assessing coastal stability the expected acceleration in relative sea level rise together with projections of increasing storm intensity and greatly diminished winter ice cover in the southern gsl implies a significant increase in coastal erosion hazards in future

younger dryas to mid holocene environmental history of the lowlands of nw transylvania romania pollen micro charcoal and total carbon analyses on sediments from the turbuta palaeolake in the transylvanian basin of nw romania reveal younger dryas to mid holocene environmental changes the chronostratigraphy relies on ams 14c measurements on organic matter and u th tims datings of snail shells results indicate the presence of pinus and betula open woodlands with small populations of picea ulmus alnus and salix before 12 000 cal yr bp a fairly abrupt replacement of pinus and betula by ulmus dominated woodlands at ca 11 900 cal yr bp likely represents competition effects of vegetation driven by climate warming at the onset of the holocene by 11 000 cal yr bp the woodlands were increasingly diverse and dense with the expansion of quercus fraxinus and tilia the establishment of corylus and the decline of upland herbaceous and shrubs taxa the marked expansion of quercus accompanied by tilia between 10 500 and 8000 cal yr bp could be the result of low effective moisture associated with both low elevation of the site and with regional change towards a drier climate at 10 000 cal yr bp corylus spread across the region and by 8000 cal yr bp it replaced quercus as a dominant forest constituent with only little representation of picea abies carpinus became established around 5500 cal yr bp but it was only a minor constituent in local woodlands until ca 5000 cal yr bp results from this study also indicate that the woodlands in the lowlands of turbuta were never closed

weichselian late pleniglacial and late glacial depositional environments coleoptera and periglacial climatic records from central poland belchatow environmental conditions during the weichselian have been studied at the belchatow brown coal pit in central poland palaeoclimate has been reconstructed by a multiproxy approach based on sedimentary environments periglacial structures and coleoptera remains the weichselian middle to late pleniglacial sequence reveals a change from lacustrine to fluvial deposition during the late pleniglacial deposition by ephemeral streams with relatively stable channels was abruptly replaced by braided river deposition an increased aridity and the disappearance of the vegetation are held reponsible for this change in river style the increase of aridity in the second part of the late pleniglacial has been inferred from the absence of organic material in the braided deposits and the extension of aeolian environments at the expense of the braided environment a return towards wetter conditions during the late glacial has been inferred from lake marl deposition and local fluvial reworking of dunes special attention has been given to the climate reconstruction of the early late pleniglacial 26 24 ka permafrost conditions during this period in combination with local strong relief and intensive slope processes resulted in rapid aggradation by ephemeral streams with relatively stable channels the climate during the early late pleniglacial was extremely harsh the habitat was in many ways analogous to the true tundra of the present day arctic the periglacial features indicate a mean annual air temperature lower than 4 c the coleopteran assemblage from belchatow is one of the most cold adapted faunas so far recorded from europe the mean temperatures of the warmest and coldest months were respectively 8 c and 27 c it is concluded that a strong temperature decline especially of the winter temperature occurred at the transition from the middle to the late pleniglacial at the onset of the late glacial younger dryas period a cooling of the climate has been inferred from the presence of small ice wedge casts at the base of overlying dune sands a mean annual air temperature between 2 and 5 c is postulated 1998 john wiley sons ltd

the last deglaciation of the southeastern sector of the scandinavian ice sheet the scandinavian ice sheet sis was an important component of the global ice sheet system during the last glaciation but the timing of its growth to or retreat from its maximum extent remains poorly known we used 115 cosmogenic beryllium 10 ages and 70 radiocarbon ages to constrain the timing of three substantial ice margin fluctuations of the sis between 25 000 and 12 000 years before the present the age of initial deglaciation indicates that the sis may have contributed to an abrupt rise in global sea level subsequent ice margin fluctuations identify opposite mass balance responses to north atlantic climate change indicating differing ice sheet sensitivities to mean climate state

a stratigraphic framework for abrupt climatic changes during the last glacial period based on three synchronized greenland ice core records refining and extending the intimate event stratigraphy due to their outstanding resolution and well constrained chronologies greenland ice core records provide a master record of past climatic changes throughout the last interglacial glacial cycle in the north atlantic region as part of the intimate integration of ice core marine and terrestrial records project protocols have been proposed to ensure consistent and robust correlation between different records of past climate a key element of these protocols has been the formal definition and ordinal numbering of the sequence of greenland stadials gs and greenland interstadials gi within the most recent glacial period the gs and gi periods are the greenland expressions of the characteristic dansgaard oeschger events that represent cold and warm phases of the north atlantic region respectively we present here a more detailed and extended gs gi template for the whole of the last glacial period it is based on a synchronization of the ngrip grip and gisp2 ice core records that allows the parallel analysis of all three records on a common time scale the boundaries of the gs and gi periods are defined based on a combination of stable oxygen isotope ratios of the ice 18o reflecting mainly local temperature and calcium ion concentrations reflecting mainly atmospheric dust loading measured in the ice the data not only resolve the well known sequence of dansgaard oeschger events that were first defined and numbered in the ice core records more than two decades ago but also better resolve a number of short lived climatic oscillations some defined here for the first time using this revised scheme we propose a consistent approach for discriminating and naming all the significant abrupt climatic events of the last glacial period that are represented in the greenland ice records the final product constitutes an extended and better resolved greenland stratotype sequence against which other proxy records can be compared and correlated it also provides a more secure basis for investigating the dynamics and fundamental causes of these climatic perturbations

cumulative versus transient shoreline change dependencies on temporal and spatial scale using shoreline change measurements of two oceanside reaches of the north carolina outer banks usa we explore an existing premise that shoreline change on a sandy coast is a self affine signal wherein patterns of change are scale invariant wavelet analysis confirms that the mean variance spectral power of shoreline change can be approximated by a power law at alongshore scales from tens of meters up to 4 8 km however the possibility of a power law relationship does not necessarily reveal a unifying scale free dominant process and deviations from power law scaling at scales of kilometers to tens of kilometers may suggest further insights into shoreline change processes specifically the maximum of the variance in shoreline change and the scale at which that maximum occurs both increase when shoreline change is measured over longer time scales this suggests a temporal control on the magnitude of change possible at a given spatial scale and by extension that aggregation of shoreline change over time is an important component of large scale shifts in shoreline position we also find a consistent difference in variance magnitude between the two survey reaches at large spatial scales which may be related to differences in oceanographic forcing conditions or may involve hydrodynamic interactions with nearshore geologic bathymetric structures overall the findings suggest that shoreline change at small spatial scales less than kilometers does not represent a peak in the shoreline change signal and that change at larger spatial scales dominates the signal emphasizing the need for studies that target long term large scale shoreline change

evidence for general instability of past climate from a 250 kyr ice core record recent results1 2 from two ice cores drilled in central greenland have revealed large abrupt climate changes of at least regional extent during the late stages of the last glaciation suggesting that climate in the north atlantic region is able to reorganize itself rapidly perhaps even within a few decades here we present a detailed stable isotope record for the full length of the greenland ice core project summit ice core extending over the past 250 kyr according to a calculated timescale we find that climate instability was not confined to the last glaciation but appears also to have been marked during the last interglacial as explored more fully in a companion paper3 and during the previous saale holstein glacial cycle this is in contrast with the extreme stability of the holocene suggesting that recent climate stability may be the exception rather than the rule the last interglacial seems to have lasted longer than is implied by the deep sea specmap record4 in agreement with other land based observations5 6 we suggest that climate instability in the early part of the last interglacial may have delayed the melting of the saalean ice sheets in america and eurasia perhaps accounting for this discrepancy

timing of the late vistulian weichselian glacial phases in poland abstract the lower vistula region in northern poland is a stratotype area for the vistulian weichselian glaciation and during last glacial maximum lgm the southernmost extension of the scandinavian ice sheet occurred in western poland and in eastern germany reinterpretation of the available geochronological data radiocarbon 36 cl and 10 be ages supplied with new field geological evidence mostly for the late vistulian ice sheet limits and movement directions was focused in three key regions in poland during the late middle vistulian there was one or two ice sheet advances in the lower vistula region the late vistulian maximum ice sheet limit in poland was time transgressive and occurred at 24 19 kyrs bp generally the younger to the east ice sheet limits during the leszno phase occurred at 24 cal 10 be 36 cl kyrs the poznan phase ice sheet limit was dated to 19 10 be 36 cl kyrs and the pomeranian phase ice sheet limit about 16 17 10 be 36 cl kyrs every late vistulian glacial phase in poland was preceded by an ice sheet retreat

an event stratigraphy for the last termination in the north atlantic region based on the greenland ice core record a proposal by the intimate group it is suggested that the grip greenland ice core should constitute the stratotype for the last termination based on the oxygen isotope signal in that core a new event stratigraphy spanning the time interval from ca 22 0 to 11 5 k grip yr bp ca 19 0 10 0 k 14 c yr bp is proposed for the north atlantic region this covers the period from the last glacial maximum through termination 1 of the deep ocean record to the pleistocene holocene boundary and encompasses the last glacial late glacial of the traditional northwest european stratigraphy the isotopic record for this period is divided into two stadial episodes greenland stadials 1 gs 1 and 2 gs 2 and two interstadial events greenland interstadials 1 gi 1 and 2 gi 2 in addition gi 1 and gs 2 are further subdivided into shorter episodes the event stratigraphy is equally applicable to ice core marine and terrestrial records and is considered to be a more appropriate classificatory scheme than the terrestrially based radiocarbon dated chronostratigraphy that has been used hitherto 1998 john wiley sons ltd

can a simple dynamical system describe the interplay between drag and buoyancy in terrain induced canopy flows abstractunder nonneutral stratification and in the presence of topography the dynamics of turbulent flow within a canopy is not yet completely understood this has among other consequences serio

mixing layers and coherent structures in vegetated aquatic flows 1 to date flow through submerged aquatic vegetation has largely been viewed as perturbed boundary layer flow with vegetative drag treated as an extension of bed drag however recent studies of terrestrial canopies demonstrate that the flow structure within and just above an unconfined canopy more strongly resembles a mixing layer than a boundary layer this paper presents laboratory measurements obtained from a scaled seagrass model that demonstrate the applicability of the mixing layer analogy to aquatic systems specifically all vertical profiles of mean velocity contained an inflection point which makes the flow susceptible to kelvin helmholtz instability this instability leads to the generation of large coherent vortices within the mixing layer observed in the model at frequencies between 0 01 and 0 11 hz which dominate the vertical transport of momentum through the layer the downstream advection of these vortices is shown to cause the progressive coherent waving of aquatic vegetation known as the monami when the monami is present the turbulent vertical transport of momentum is enhanced with turbulent stresses penetrating an additional 30 of the plant height into the canopy

a multiproxy study of younger dryas and early holocene climatic conditions from the grabia river paleo oxbow lake central poland abstract a multi proxy reconstruction of water depth temperature and precipitation inferred from cladocera chironomidae and pollen assemblages has been obtained from wierczyna paleo oxbow central poland during the younger dryas yd and early holocene results suggest that the yd was relatively cold and comprised two main phases the first ca 12 500 12 000 cal yrs bp is characterized by a continental climatic regime and a decrease in winter temperatures and precipitation but an increase in spring summer precipitation the second phase ca 12 000 11 500 cal yrs bp was more mild with a variable continental climate an increase in summer and winter temperature a lengthening of the growing season and increased annual precipitation the reconstructed water level generally follows changes in spring and summer precipitation and length of growing season the frequency and timing of hydroclimatic oscillations at wierczyna show strong similarities to records from other sites in europe this confirms that oxbows and valley mire ecosystems respond to rapid climate change during the yd and early holocene this study therefore brings new insights into the effects of climate changes on river environments especially during the yd we also discuss the limitations of water depth temperature and precipitation reconstructions inferred from the studied biotic assemblages

oxygen isotopes of lake marl at gerzensee and leysin switzerland covering the younger dryas and two minor oscillations and their correlation to the grip ice core the ratio of oxygen isotopes is a temperature proxy both in precipitation and in the calcite of lacustrine sediments the very similar oxygen isotope records from greenland ice cores and european lake sediments during the last glacial termination suggest that the drastic climatic changes occurred quasi simultaneously on an extra regional probably hemispheric scale in order to study temporal relations of the different parameters recorded in lake sediments for example biotic response times to rapid climatic changes a precise chronology is required in unlaminated lake sediments there is not yet available a method to provide a high resolution chronology especially for periods with radiocarbon plateaux alternatively an indirect time scale can be constructed by linking the lake stratigraphy with other well dated climate records new oxygen isotope records from gerzensee and leysin with an estimated sampling resolution of between 15 and 40 years match the greenlandic isotope record in many details under the assumption that the main variations in temperature and thus in oxygen isotopes occurred about simultaneously in greenland and switzerland we have assigned a time scale to the lake sediments of gerzensee and leysin by wiggle matching their stable isotope records with those of greenland ice cores which are among the best dated climatic archives we estimate a precision of 20 to 100 years during the last glacial termination

the climatic control of sedimentary environment changes during the weichselian an example from the middle vistula region eastern poland abstract this study presents the sedimentary facies stratigraphic framework and palaeoenvironmental conditions of the weichselian sediments in the middle vistula region based on sedimentological palynological palaeopedological and absolute age studies luminescence and radiocarbon dating a succession of three lithofacial complexes and the pattern of their evolution was distinguished the lowermost fluvial complex is composed of two parts separated by an extensive erosional surface they were deposited in a braided river system during two distinct periods of weichselian climate cooling first at the end of the marine isotope stage 5a and during the entire marine isotope stage mis 4 and then at the end of mis 2 late glacial the middle fluvio aeolian complex was deposited during the late glacial as an effect of alternating fluvial and aeolian processes on abandoned higher river terraces under periglacial conditions discontinuous permafrost it represents a record of climatic amelioration culminating in the succession of tundra vegetation and sparse pine birch forests causing the formation of a soil in the top part of the middle complex the uppermost aeolian complex was deposited during the older and younger dryas as a result of permafrost degradation the deposition was interrupted by the expansion of boreal forest during the allerod and the development of soils climate has been recognized as a major factor determining changes in sedimentary environments the cooling of the climate during the weichselian was conducive to the aggradation of sediments and permafrost in contrast climate warming resulted in increased erosion in the valley and creation of terraces

analysis of the spatio temporal behaviour of beach morphology at duck using fractal methods abstract in this study monthly beach elevation time series between 1981 and 2003 at duck north carolina are analysed using fractal methods this work extends a fractal analysis carried out by southgate and moller southgate h n moller i 2000 fractal properties of coastal profile evolution at duck north carolina j geophys res 105 c5 11489 11507 using twice the amount of data 22 3 yr with the aim of investigating the fractal properties at different profile locations over a larger range of timescales differences in fractal properties between the periods 1981 1992 and 1992 2003 are also examined the results of this analysis are used to distinguish between the timescales on which the beach elevation responses at various cross shore and alongshore locations are related or unrelated to external forcing two fractal analysis approaches based on the calculation of global and local hurst exponents are used the local hurst exponent method identifies local fractal properties in the data over ranges of timescales and also accounts for nonstationarity in relation to the data mean hence it is considered to be a more appropriate technique for identifying the fractal properties in such dynamic natural time series the analysis of the entire 22 3 year long data set shows fractal properties over more varied timescales and beach locations than previously observed by southgate and moller southgate h n moller i 2000 fractal properties of coastal profile evolution at duck north carolina j geophys res 105 c5 11489 11507 for the dune and upper shoreface fractal properties are estimated at timescales between 1 and 50 months while the inner and outer bar zones exhibit fewer fractal properties over varied timescales between 10 and 90 months cross shore locations corresponding to the typical positions of the nearshore sand bars at duck exhibit non fractal properties reflecting the dominant influences of wave forcing in these areas alongshore differences in the fractal properties which were not previously studied are also identified between the pairs of profile lines located north and south of the frf pier these observations demonstrate the importance of studying both alongshore and cross shore morphological variability the differences in the spatio temporal patterns of the fractal properties identified for the 1981 1992 and 1992 2003 periods illustrate the variation of the beach morphology with time this demonstrates the need for re evaluating beach behaviour using extended data the present work shows that the timescales on which fractal properties are estimated are consistent with the timescales on which previous studies found the influences of the external forcing conditions at duck to be relatively weak

very fast environmental changes at the pleistocene holocene boundary recorded in laminated sediments of lake gościz poland abstract this paper presents a reconstruction of the climatic changes at the pleistocene holocene transition recorded in the annually laminated sediments of lake go ci a z poland this reconstruction is based on pollen stable isotope mineralogical and chemical analyses of sediments made with a time resolution of 1 4 yr it reveals a sequence of abrupt climatic changes which preceded and followed the major warming around 11 500 cal bp our data show that the warming period was preceded by a 30 yr long phase of increased winter and decreased summer precipitation 11 550 11 520 cal bp about 11 520 cal bp a very brief period of wetter conditions occurred simultaneously with the beginning of the major warming however most of the first phase of the major warming 11 520 11 500 cal bp was characterised by a generally dry climate presumably due to lowered winter precipitation our records suggest that in this phase the warming concerned winter seasons mostly in the second phase 11 500 11 460 cal bp the warming also concerned summer seasons also a distinct increase of humidity is noted in this period which caused moistening of soils and despite enhanced evaporation and evapotranspiration inhibited the process of lake level drop the following 70 years 11 460 11 390 cal bp were rather dry which caused a distinct lowering of the lake and probably also of groundwater level in this period maximum biological productivity per unit area in the lake is noted the whole sequence of phases of rather different climates was completed within a time interval 160 years spanning two human lifes only one should stress that the transitions between the consecutive phases were rather abrupt lasting no longer than 10 years

sandbars in motion nearshore surf zones are turbulent places yet despite the apparently chaotic nature of the sea surface in these areas sandbars often show complex patterns with an intricate structure in their perspective stive and reniers discuss recent efforts to understand how these patterns form they highlight the report by hoefel and elgar who consider a new transport mechanism based on flow acceleration within the waves this mechanism should help to improve the predictability of sandbar structures

past hydrological events reflected in holocene history of polish rivers abstract a database of 335 radiocarbon dates from holocene fluvial sediments in poland has been compiled each sample is characterized by 25 parameters all samples were grouped into one of 7 regions characterized by hydrological regime and one of 8 depositional environments statistical analysis was used to enhance the palaeoenvironmental data and 17 phases may be distinguished 10 of which have a distinct sharp peak abandoned paleochannels 149 dates clearly reflect the major wetter phases of the holocene an opposite picture is presented by overbank aggradation 86 dates connected mainly with expansion of agriculture preliminary correlations are made on peat bog records changes in vegetation lake water level rates calcareous tufa and speleothems growth landslides phases and debris flow phases these show many convergences explained by climatic fluctuations during the holocene

fractal properties of coastal profile evolution at duck north carolina observed variations in coastal morphology on monthly to decadal timescales are often difficult to explain in terms of physical processes operating on shorter timescales one reason could be that the morphology evolves to high dimensional self organized states circumstantial evidence for this would be indicated by fractal distributions of the dynamical variables fractal analysis techniques are applied to beach level time series collected at duck north carolina united states after processing for this study the data set consists of time series of monthly beach and nearshore levels at up to 86 locations at 10 m spacing along each of four shore normal profile lines over a period of 10 5 years time series of shoreline positions are also analyzed several fractal analysis techniques are used based on the hurst exponent h and various sources of error are considered and quantified results indicate different fractal behavior in different cross shore zones h values of around 0 5 are found in the nearshore bar zones and are thus consistent with a random gaussian process while values around 0 8 are found farther offshore and on upper parts of the beach indicating long range persistency further analyses are done to determine time spans over which fractal behavior occurs generally fractal responses are found at locations and timescales where the temporal variations of wave forcing are relatively weak suggestions are made to interpret these findings in terms of forced and self organized morphodynamic change in different cross shore zones and over different timescales some possible implications for predicting future coastal morphology are discussed