investigations on the morphodynamics of sandy tidal flats a modeling application in coastal research tidal flats are often classified and investigated in the context of estuarine dynamics due to the widely accepted view that tidal forces are the main responsible for their geomorphological evolution and that biological variables need to play a major role in its evolution on the other hand coastal morphodyanmics deals mostly with geomorphological evolution of beaches taking a purely geological view on sediment dynamics in this paper a discussion is presented in relation to the adequate treatment of tidal flat research by illustrating various numerical and empirical methods used to address morphodynamics on the sandy tidal flats of newtownards common to other sandy tidal flats the intertidal shores of newtownards in strangford lough northern ireland are affected by tidal flows c 0 1 ms 1 given the average tidal range of 3 5 m and the action ofwind generated waves over the fine grained siliciclastic sediments which frequently shows rippled surfaces the results from a wide range of investigations previously published that utilized mainly numerical modeling indicated that the flats of newtownards characterized by a rtr relative tidal range factor of 2 3 to 7 are very sensitive to sediment redistribution due to combined water level wave height effects which implies that waveenergy dissipation due to bottom friction the primarily shoaling process during relative high energy events using empirical methods designed for beach morphodynamics research it was found that i waves exceeded predicted values given short fetch under westerly winds ii wave penetration was a parameter that proved extremely sensitive for sediment entrainment and was not sufficient to generate bedload sediment transport and iii further numerical simulations need to be conducted to achieve further understanding on the role of shoalingand spatial distribution of wave energy dissipation on the translating surf and nearshore zones to achieve a complete morphodynamic classification of these ultra mega dissipative wave dominated environments

digital elevation model resolution effects on terrain attribute calculation and quantitative soil landscape modeling the accuracy of digital elevation models dem and dem derived products depends on several factors including the horizontal resolution and vertical precision at which the elevation data are represented and the source of the elevation data this accuracy becomes increasingly important as we extend the use of dem data for spatial prediction of soil attributes our objective was to compare terrain attributes and quantitative soil landscape models derived from grid based dem represented at different horizontal resolutions 10 and 30 m represented at different vertical precisions 0 1 and 1 m and acquired from different sources decreasing the horizontal resolution of the field survey dem produced lower slope gradients on steeper slopes steeper slope gradients on flatter slopes narrower ranges in curvatures larger specific catchment areas in upper landscape positions and lower specific catchment areas values in lower landscape positions overall certain landscape features were less discernible on the 30 m dem than on the 10 m dem decreased vertical precision produced a large proportion of points with zero slope gradient and zero slope curvature and a large number of steeply sloping and more highly curved areas differences among dem from different sources were more significant with less accurate representation of depressions and drainage pathways with the usgs dem as compared to the field survey dem empirical models developed from different dem included similar predictive terrain attributes and were equally successful in predicting a horizon depth ahd in the validation data set

contribution of hydrodynamic conditions during shallow water stages to the sediment balance on a tidal flat mont saint michel bay normandy france field measurements were conducted in mont saint michel bay a megatidal embayment spring tidal range of 15 m in order to monitor over the course of a tidal cycle sediment transport variability due to waves and tides on the upper part of a tidal at characterised by shallow water depths sensors used to measure currents water depth and turbidity were installed just above the bed 0 04 m two experiments were conducted under contrasting hydrodynamic conditions the results highlight wave activity over the tidal at even though observed wind waves were largely dissipated due to the very shallow water depths very high suspended sediment concentrations up to 6 kg m3 were recorded in the presence of wave activity at the beginning of the local ood when signi cant sediment transport occurred up to 7 times as much as under conditions of no wave activity this in uence may be attributed to the direct action of waves on bed sediments to wave induced liquefaction and to the erosive action of waves on tidal channel banks the sediment composition comprising a clay fraction of 2e5 may also enhance sediment transport by reducing critical shear stress through the sand lubrication effect the results also show that antecedent meteorological conditions play an important role in suspended sedi ment transport on the tidal at total sediment ux directions show a net transport towards the inner part of the bay that contributes to deposition over the adjacent salt marshes and this tendency also prevails during strong wave conditions such sediment transport is characterised by signi cant vari ability over the course of the tidal cycle during fair and moderate weather conditions 83 and 71 of the total ux was observed respectively over only 11 and 28 of the duration of the local tidal cycle and with water depths between 0 04 and 0 3 m these results suggest that in order to improve our under standing of sediment budgets in this type of coastal environment it is essential to record data just at the beginning and at the end of tidal submergence close to the bed

landform classification and soil distribution in hummocky terrain saskatchewan canada this study presents a classification of distinct three dimensional landform elements and examines the relationship between these landform elements and selected soil morphological properties of udic boroll soils in southern saskatchewan canada the classification is based on defined ranges of three criteria derived from topographic data gradient profile downslope curvature and plan across slope curvature seven landform elements are recognized convergent shoulders divergent shoulders convergent backslopes divergent backslopes convergent footslopes divergent footslopes and level elements all of the elements are easily identified in the field the thicknesses of a horizons and depths to calcium carbonate of the soils were consistently greater in convergent versus divergent elements in the same profile group e g shoulders and showed an overall increase in the sequence shoulders backslopes level footslope elements distinct groups of elements emerge from a statistical analysis of the differences between individual and bivariate means of soil morphological properties associated with each landform element the differences in soil properties among the elements can be largely explained by differences in water movement and distribution in hillslope systems the results of the study highlight the need to consider land surface morphology during the development of research designs for soil related studies

relationships between wave induced currents and sediment grain size on a sandy tidal flat studies of sedimentation on sandy tidal flats have long acknowledged that tidal flows and waves are the most influential hydrodynamic forcing factors operating on surficial sediments tidal flows influence the long term evolution of tidal flats because of the asymmetry of tidal regimes flood and ebb tidal current activity is mainly confined to channels outside the channels mainly on the upper tidal flats tidal current velocities decrease and sediment entrainment is frequently ascribed to wave action the role of wave induced processes on intertidal flat sediments is frequently stated but has seldom been investigated apparently because of methodological constraints in this paper we report on investigations into the role of wave processes in determining surficial sediment distribution patterns on a sandy tidal flat at newtownards at the northern end of strangford lough northern ireland spring tidal range 3 5 m the main aim of this paper is to investigate the potential relationship between wave induced processes and surficial sediments without attempting to achieve a comprehensive analysis of other sedimentation the methodological approach involves numerically modeling wave propagation and comparing this with sediment distribution on a controlled field site the method enables the role of waves on tidal flats to be more fully assessed waves were modeled at a variety of tidal levels and wave data were extracted from the model grid at positions co incident with sediment sampling locations multiple correlation of sediment mean grain size with simulated wave induced orbital velocity showed a distinctive variation in correlation coefficients according to water level the best and statistically significant correlations occur when water levels occupy a vertical range between 0 15 and 1 0 m local ordnance level od in the absence of strong tidal currents sediment distribution appears to be best explained by waves acting at these water levels it is inferred that at lower than optimum water levels wave energy is less influential on sediment texture since 1 part of the tidal flat is still exposed and 2 the fetch over which the waves are generated is reduced at higher than optimum water levels wave energy may be sufficient to transport sediment but the wave penetration in the column of water is not sufficient to permit wave energy dissipation at the sediment surface tidal currents are dominant at low tidal elevations so outside channels wave induced currents exert most influence on the tidal flats

a new geodynamical thermal model of rift evolution with application to the dnieper donets basin ukraine abstract a model of the lithosphere incorporating both dynamic and thermal processes has been developed by solving a coupled system of differential equations governing stress and temperature in a 2 d block structured geophysical medium designed to study the roles of tectonic and geothermal factors in continental rift formation and evolution the model incorporates syn sedimentary and or erosional faulting of an upper crustal layer and allows the thermal regime of the lithosphere to be calculated through time the method has been applied to the formation and evolution of the northwest dnieper donets basin ddb along one regional profile controlled by seismic and other geophysical and subsurface data the results are compared with those published earlier for the same profile using different methods of modelling the rift and early post rift development of the region the final basement geometry at the end of the rifting stage predicted by the new model satisfactorily corresponds with geological data and is qualitatively similar to that predicted by the previously published models however the new results imply an important role for an active mechanism during rifting that generates greater mantle thinning than crustal thinning and elevated temperatures in the upper mantle beneath the rift

architecture and depositional sequences of tertiary fault block carbonate platforms an analysis from outcrop miocene gulf of suez and computer modelling abstract this study combines outcrop with seismic data and tectonostratigraphic modelling to characterise the stratigraphy of tertiary fault block carbonate platforms seismic sections from the middle east and southeast asia indicate that carbonate platforms commonly develop on fault blocks in the late syn rift to post rift stage of basin evolution they are characterised by retrogradational or drowning morphologies with deep water clastics evaporites sealing the platforms a new tectono stratigraphic modelling program simulates the development of carbonate platforms on domino style fault blocks and predicts a distinctive tectonic control on the evolving syn rift stratigraphy detailed field work from a three dimensionally exposed miocene syn rift platform from the gulf of suez gebel abu shaar egypt shows the existence of unconformity bound depositional sequences which are predicted by the program and are interpreted to have formed in response to fault block rotation the sequences are characterised by synchronous hangingwall subsidence and footwall uplift and erosion the seismic images the modelling and the outcrop study provide different levels of information on fault block platforms and their characteristic stratigraphy the scale of the modelling is of particular value as it provides a link between the seismic scale imaging and outcrop data

temporal and spatial variation in intertidal sedimentation rates sediment deposition and erosion rates are reported for an intertidal zone in the burry inlet south wales measured deposition rates over the salt marsh are compared with deposition rates calculated from observed suspended sediment concentrations notably it is concluded that residual turbulence at slack water should not be discounted when calculating deposition rates grain size distributions of suspended sediments over the marsh surface during flood and ebb tides contrast with the grain size distribution of deposited marsh sediments the latter being significantly coarser these data in conjunction with mass budget calculations are used to relate total annual deposition and sediment supply by tidal action during settled meteorological periods the analysis suggests that episodic storm induced sediment transport is probably an important mechanism for introducing coarse sediment on to the marsh surface finally it is noted that seasonal reworking of the sandy non cohesive sediments may be related to variations in the intensity of wave breaking throughout the year

field observations of sand mixing depths on steep beaches abstract a series of field studies were carried out on three portuguese beaches garra o faro and culatra to assess sand mixing depths under a range of wave heights 0 34 0 80 m wave periods 5 1 7 0 s and mean grain sizes 0 26 and 0 38 mm all the studied beaches had a reflective profile with a steep upper foreshore tan of 0 10 0 14 and a more gentle low tide terrace in all experiments plunging waves were breaking on the beach face the study has identified a linear correlation between significant wave height at breaking h b and average sand mixing depth z m whereby z m 0 27h b the empirical relationship is ten times larger than a previous one proposed by other authors working on gentle slope dissipative beaches and confirms previous findings on similar reflective beaches carried out in the usa it was also confirmed that z m is related to wave period but does not seem to be a function of mean sand size

combined escape tectonics and subduction rollback back arc extension a model for the evolution of tertiary rift basins in thailand malaysia and laos the tertiary rift basins of thailand and adjacent countries show considerable variability in the timing of rift initiation termination the timing and magnitude of thermal subsidence and the timing and intensity of inversion episodes the rift basins developed on continental blocks that were extruded southeastwards hence their development must be tied into himalayan extrusion tectonics current tectonic models propose that the tertiary basins opened up as pull apart basins associated with strike slip faults published geochronology of strike slip fault zone rocks mapping of fault patterns in the tertiary basins and mapped releasing restraining bend geometries all indicate that in thailand major sinistral strike slip motion ceased at about 30 ma prior to the formation of most rift basins the thailand the effects of later dextral slip were minor and probably a result of reactivation during episodes of inversion during nw se to ne sw himalayan compression dextral slip was not responsible for opening most of the rift basins in thailand an alternative mechanism to open the rift basins is subduction rollback of the indian plate to the west of thailand it is proposed that subuction rollback can help explain some of the characteristics of the rift basins such as non uniform lithospheric extension deep sag basins and the diachronous onset and termination of rifting

automated classifications of topography from dems by an unsupervised nested means algorithm and a three part geometric signature abstract an iterative procedure that implements the classification of continuous topography as a problem in digital image processing automatically divides an area into categories of surface form three taxonomic criteria slope gradient local convexity and surface texture are calculated from a square grid digital elevation model dem the sequence of programmed operations combines twofold partitioned maps of the three variables converted to greyscale images using the mean of each variable as the dividing threshold to subdivide increasingly subtle topography grid cells sloping at less than mean gradient of the input dem are classified by designating mean values of successively lower sloping subsets of the study area nested means as taxonomic thresholds thereby increasing the number of output categories from the minimum 8 to 12 or 16 program output is exemplified by 16 topographic types for the world at 1 km spatial resolution srtm30 data the japanese islands at 270 m and part of hokkaido at 55 m because the procedure is unsupervised and reflects frequency distributions of the input variables rather than pre set criteria the resulting classes are undefined and must be calibrated empirically by subsequent analysis maps of the example classifications reflect physiographic regions geological structure and landform as well as slope materials and processes fine textured terrain categories tend to correlate with erosional topography or older surfaces coarse textured classes with areas of little dissection in japan the resulting classes approximate landform types mapped from airphoto analysis while in the americas they create map patterns resembling hammond s terrain types or surface form classes srtm30 output for the united states compares favorably with fenneman s physical divisions experiments are suggested for further developing the method the arc info aml and the map of terrain classes for the world are available as online downloads

differences in topographic characteristics computed from 100 and 1000 m resolution digital elevation model data topographic characteristics computed from 100 and 1000 m resolution digital elevation model dem data are compared for 50 locations representing varied terrain in the conterminous usa the topographic characteristics are three parameters used extensively in hydrological research and modelling slope s specific catchment area as and a wetness index computed as the logarithm of the specific catchment area divided by slope ln as s slope values computed from 1000 m dems are smaller than those computed from 100 m dems specific catchment area and the wetness index are larger for the 1000 m dems compared with the 100 m dems most of the differences between the 100 and 1000 m resolution dems can be attributed to terrain discretization effects in the computation of the topographic characteristics and are not the result of smoothing or loss of terrain detail in the coarse data in general the terrain discretization effects are greatest on flat terrain with long length scale features and the smoothing effects are greatest on steep terrain with short length scale features for the most part the differences in the average values of the topographic characteristics computed from 100 and 1000 m resolution dems are predictable that is biases in the mean values for the characteristics computed from a 1000 m dem can be corrected with simple linear equations copyright 2000 john wiley sons ltd

quantitative analysis of land surface topography land surface topography significantly affects the processes of runoff and erosion a system which determines slope aspect and curvature in both the down slope and across slope directions is developed for an altitude matrix also the upslope drainage area and maximum drainage distance are determined for every point within the altitude matrix a fortran 66 program performs the analysis

a semi automated method for mapping glacial geomorphology tested at breiðamerkurjokull iceland abstract despite advances in data collection and analytical software mapping of glacial geomorphology is still largely achieved through manual techniques manual mapping is a relatively slow inefficient and potentially subjective process particularly given the extensive spatial coverage of remotely sensed datasets thus glacial geomorphic mapping would benefit from semi automated techniques able to map large areas quickly and efficiently here we develop novel semi automated techniques for mapping glacial geomorphology based on lidar derived data collected from brei amerkurjokull iceland using object based image analysis obia the landforms classified were moraines eskers flutes drumlins and glacio fluvial outwash several land surface parameters lsps were calculated during image segmentation and analysis representing the characteristics of the landforms of interest the segmentation and classification routines were developed in matlab whereas most attempts so far have used specialised obia software our techniques utilised exploratory data analysis where statistical groupings within the data define different landform types accuracy was assessed against a reference map derived using traditional manual mapping techniques landforms were classified to an overall accuracy of 77 our semi automated mapping techniques should with further algorithm development be applicable using other datasets commonly used in palaeo glaciology such as radar derived elevation data and swath bathymetry

a new procedure for gridding elevation and stream line data with automatic removal of spurious pits abstract a morphological approach to the interpolation of regular grid digital elevation models dems from surface specific elevation data points and selected stream lines is described the approach has given rise to a computationally efficient interpolation procedure which couples the minimization of a terrain specific roughness penalty with an automatic drainage enforcement algorithm the drainage enforcement algorithm removes spurious sinks or pits yielding dems which may be used to advantage in hydrological process studies the drainage enforcement algorithm has also been found to significantly increase the accuracy of dems interpolated from sparse but well chosen surface specific elevation data moreover it facilitates the detection of errors in elevation data that would not be detected by more conventional statistical means and forms a sound physical basis for cartographic generalization

optimisation of relief classification for different levels of generalisation abstract relief plays an important role in the spatial and temporal distribution of soil water and matter transport processes each landscape can be segmented into different landform elements based on a digital elevation model these landforms contain characteristic properties in terms of energy and material balance several algorithms are available to classify landscapes at different scales however lack of knowledge exists concerning the applicability of relief parameters for landscape stratification for different generalisation levels of underlying data the objective of this study was to develop a method for agricultural landscapes to classify landform elements across a series of elevation datasets with different spatial resolutions a non linear parameter optimisation algorithm was coupled with a relief classification scheme to optimize four classification parameters with regard to environmentally sensitive landforms shoulder and footslope input datasets were based on a lidar scan and topographic maps the magnitude of the optimized relief parameters decreased with decreasing map scale from 1 10 000 to 1 100 000 or increasing contour line interval the main conclusion is that if one set of classification rules for a specific landscape was determined for a high resolution dataset at a small subset it could be applied for larger areas even if only coarser digital elevation model information were available

identification of the spatial distribution of soils using a process based terrain characterization abstract a simple process based terrain characterization model was developed to identify the occurrence of soils over a complex landscape its basic proposition is that soil distribution can be most efficiently identified by the separation of pedogeomorphological units where similar hydrological geomorphological and pedological processes occur the proposed model is a three dimensional extension of the nine unit soil landscape model the two dimensional conceptual and qualitative model is reinterpreted in terms of continuity equations describing the distribution of soil materials over hillslopes and is implemented in a geographical information system gis through the analysis of a raster digital elevation model dem the application of this model at the empire prairie in southern wisconsin usa shows a good agreement with the results of a soil investigation the difficulty in modeling the diverse geomorphological and pedological processes at low lying slope positions and the influence of relict pedological features on contemporary soil formation however remain unsolved this model can consider the spatial variability of soils both at the continuous and discrete scales and is easily transferable to other slopes in a predictive manner it is further expected to provide a quantitative tool to characterize surface topography in terms of process identification and resource survey and also a priori information for spatially distributed ecological and environmental models

measuring the relative topographic position of archaeological sites in the landscape a case study on the bronze age barrows in northwest belgium abstract local topography is an important parameter determining the erection of a certain type of site on a certain location in the landscape despite the importance of topography in archaeological landscape research the role of local topography has remained rather unexplored compared to other specific topographic parameters such as slope aspect curvature or visibility therefore three methods to assess the relative topographic position of sites are applied and discussed here the bronze age barrow dataset of northwest belgium acts as the subject for this methodological case study first elevation percentile calculates the area that is lower than the central point within a predetermined neighborhood secondly difference from mean elevation measures the relative topographic position of the central point as the difference between the elevation of this central point and the mean elevation within a predetermined neighborhood and finally deviation from mean elevation calculates the relative topographic position of the central point as the difference from mean elevation divided by the standard deviation of elevation within a predetermined neighborhood these three methods each with their advantages and disadvantages prove to be an added value for archaeological landscape research

object representations at multiple scales from digital elevation models in the last decade landform classification and mapping has developed as one of the most active areas of geomorphometry however translation from continuous models of elevation and its derivatives slope aspect and curvatures to landform divisions landforms and landform elements is filtered by two important concepts scale and object ontology although acknowledged as being important these two issues have received surprisingly little attention this contribution provides an overview and prospects of object representation from dems as a function of scale relationships between object delineation and classification or regionalization are explored in the context of differences between general and specific geomorphometry a review of scales issues in geomorphometry ranging from scale effects to scale optimization techniques is followed by an analysis of pros and cons of using cells and objects in dem analysis prospects for coupling multi scale analysis and object delineation are then discussed within this context we propose discrete geomorphometry as a possible approach between general and specific geomorphometry discrete geomorphometry would apply to and describe land surface divisions defined solely by the criteria of homogeneity in respect to a given land surface parameter or a combination of several parameters homogeneity in its turn should always be relative to scale

the land morphology concept and mapping method and its application to mainland portugal abstract land morphology influences and shapes the distribution of biodiversity agricultural production and economic activity it can be systematized into landforms and quantitatively categorized using the land morphology concept lmc the lmc classifies landforms according to their hydrological position in the watershed this paper presents an automated method to categorize lmc in a way that facilitates land morphology mapping lmm by using three criteria flat areas surface curvature and hydrological features the lmm presents a different view to evaluate and describe landforms by distinguishing valley bottoms and hilltops from flat areas considered as a landform per se in common practice in landform classification the main goal is to establish and validate criteria to automatize lmm method and create a 25 m spatial resolution gis map of mainland portugal s land morphology and landforms the validation of the automated lmm method was done by comparison between automated and manual procedures in three representative portugal landforms to evaluate the compatibility between national and local scales the lm map was compared with two local level applications using the same automated lmm method for the lisbon and loures municipalities the lm map was also compared with the distribution of soils from wet system in order to interpret local relationships between soils distribution and landforms and two widely known automated landform classifications the results show that the automated lmm method and data used is robust enough to map landforms on a national scale with sufficient detail to capture finer landforms details at the local scale this method can be applied across regions and countries simply by modifying slope gradient and is a complementary tool to other landform classifications to solve the mapping issues that occur in flat areas when the hillslope is absent it also may contribute to enhance ecological land unit s maps and soil maps by modelling natural systems and map ecosystem services accurately e g valley bottoms and floodplains give information about flood risk areas it may contribute to support environmental and planning authorities in taking decisions based on a more thorough analysis of land value and ecological functions across scales

error in a usgs 30 meter digital elevation model and its impact on terrain modeling calculations based on us geological survey usgs digital elevation models dems inherit any errors associated with that particular representation of topography we investigated the potential impact of error in a usgs 30 m dem on terrain analysis over 27 km 2 the difference in elevation between 2652 differential global positioning systems measurements and usgs 30 m dem derived elevations provided the comparative error dataset analysis of this comparative error data suggested that although the global average error is small local error values can be large and also spatially correlated stochastic conditional simulation was used to generate multiple realizations of the dem error surface that reproduce the error measurements at their original locations and sample statistics such as the histogram and semivariogram model the differences between these alternative error surfaces provide a model of uncertainty for the unknown dem error spatial distribution these dem errors had a significant impact on terrain attributes which compound elevation values of many grid cells e g slope wetness index etc a case study using terrain modeling demonstrates that the result of error propagation is most dramatic in valley bottoms and along streamlines q 2000 elsevier science b v all rights reserved

processes driving estuary infilling by marine sands on an embayed coast abstract detailed measurements of waves currents and sediment transport from an intertidal sandflat at the mouth of a partially filled new zealand estuary in an embayment with low littoral drift are presented with a view to establishing how marine sands are transported into the estuary waves mobilised sediments during episodic events early in events when waves were energetic sediments were in motion throughout the tidal cycle under abating waves sediment motion became intermittent finally becoming restricted to periods around low tide when wave orbital motions were able to penetrate to the bed three components of the total sediment flux were estimated from the data and analysed 1 a wind driven current which presumably has a complicated spatial expression in the vicinity of the estuary mouth controlled the net i e integrated over event direction of flux of suspended sediment entrained by waves and advected by currents there was no evidence of non symmetry over the tidal cycle in the suspension process that might drive a net sediment flux however there is some suggestion that lag in growth and decay of the estuary wave field over the tidal cycle systematically enhances offshore transport 2 net bedload transport by waves and currents was directed onshore which was guaranteed by two mechanisms firstly increasing wave orbital current skewness as the tide ebbed turned bedload transport onshore late in the ebb tide against the current and secondly bedload peaked early in the flood tide when skewed waves were reinforced by the flooding current 3 correlation between seaward directed forced mean flow and enhanced suspension under groups of high waves resulted in persistent offshore flux of suspended sediment at infragravity frequencies suspended sediment flux carried by gravity waves was directed seawards on flood tides and counter to the waves and onshore on ebb tides and with the waves which was explained in terms of a simple vortex ejection model we conclude that sediment transport on the sandflat at the mouth of this partially filled estuary is governed by subtle interactions between waves and currents that vary over the tidal cycle some interactions such as those that drive bedload transport promote estuary infilling by marine sands and others such as those that drive suspended sediment flux at infragravity frequencies do the opposite

control of extensional transfer zones on syntectonic and post tectonic sedimentation implications for hydrocarbon exploration the gulf of suez red sea rift system exhibits superb outcrop examples of extensional transfer zones and displays the control of these zones on syntectonic and post tectonic sedimentation hard and soft linkage transfer zones were identified at variable scales hard linkage transfer zones form inward and outward fault kinks whereas soft linkage transfer zones form relay ramps between overlapping rift parallel faults the two types of transfer zones invariably exerted fundamental control on the deposition of syn and post tectonic sediments flow direction of drainage systems and locations of sediment entry points as well as the intensity of erosion patterns of the structurally high sediment source areas this study highlights the close relationship between the transfer zones and hydrocarbon accumulations in clastic syntectonic reservoirs in rift basins

combining geomorphometry feature extraction techniques and earth surface processes research the way forward abstract in recent years the wealth of technological development revolutionised our ability to collect data in geosciences due to the unprecedented level of detail of these datasets geomorphologists are facing new challenges giving more in depth answers to a broad er range of fundamental questions across the full spectrum of the earth s and planetary processes this contribution builds on the existing literature of geomorphometry the science of quantitative land surface analysis and feature extraction translate land surface parameters into extents of geomorphological elements it provides evidence of critical themes as well as emerging fields of future research in the digital realm supporting the likely effectiveness of geomorphometry and feature extractions as they are advancing the theoretical empirical and applied dimension of geomorphology the review further discusses the role of geomorphometric legacies and scientific reproducibility and how they can be implemented in the hope that this will facilitate action towards improving the transparency and efficiency of scientific research and accelerate discoveries in geomorphology in the current landscape substantial changes in landforms ecosystems land use hydrological routing and direct anthropogenic modifications impact systems across the full spectrum of geomorphological processes although uncertainties in the precise nature and likelihood of changes exist geomorphometry and feature extraction can aid exploring process regimes and landscape responses taken together they can revolutionise geomorphology by opening the doors to improved investigations crossing space and time scales blurring the boundaries between traditional approaches and computer modelling and facilitating cross disciplinary research ultimately the exploitation of the available wealth of digital information can help to translate our understanding of geomorphic processes which is often based on observations of past or current conditions into the rapidly changing future

elementary forms for land surface segmentation the theoretical basis of terrain analysis and geomorphological mapping abstract land surface morphology is fundamental to geomorphological mapping and many gis applications review and comparison of various approaches to segmentation of the land surface reveals common features and permits development of a broad theoretical basis for segmentation and for characterization of segments and their boundaries within the context of defining landform units that maximise internal homogeneity and external differences this paper introduces the concept of elementary forms segments units defined by constant values of fundamental morphometric properties and limited by discontinuities of the properties the basic system of form defining properties represents altitude and its derivatives constant values of which provide elementary forms with various types of homogeneity every geometric type of elementary form can be characterized by a defining function which is a specific case of the general polynomial fitted function various types of boundary discontinuity and their connections and transformations into other types of morphological unit boundaries are analysed the wealth of types of elementary forms and their boundaries is potentially unbounded and thus is sufficient to cover the real variety of landforms elementary forms in the basic set proposed here have clear potential for genetic and dynamic interpretation a brief worked example documents the possibility of analytical computation of various models of ideal elementary forms for particular segments of landform ideal elementary forms can be considered as attractors to which the affinity of surface segments can be measured by multivariate statistical methods the use of the concept of elementary forms in landscape segmentation is promising and it could be adapted for elementary segmentation of various other spatial fields

semi automated mapping of landforms using multiple point geostatistics abstract this study presents an application of a multiple point geostatistics mps to map landforms mps uses information at multiple cell locations including morphometric attributes at a target mapping cell i e digital elevation model dem derivatives and non morphometric attributes i e landforms at the neighboring cells to determine the landform the technique requires a training data set consisting of a field map of landforms and a dem mapping landforms proceeds in two main steps first the number of cells per landform class associated with a set of observed attributes discretized into classes e g slope class is retrieved from the training image and stored in a frequency tree which is a hierarchical database second the algorithm visits the non mapped cells and assigns to these a realization of a landform class based on the probability function of landforms conditioned to the observed attributes as retrieved from the frequency tree the approach was tested using a data set for the buech catchment in the french alps we used four morphometric attributes extracted from a 37 5 m resolution dem as well as two non morphometric attributes observed in the neighborhood the training data set was taken from multiple locations covering 10 of the total area the mapping was performed in a stochastic framework in which 35 map realizations were generated and used to derive the probabilistic map of landforms based on this configuration the technique yielded a map with 51 2 of correct cells evaluated against the field map of landforms the mapping accuracy is relatively high at high elevations compared to the mid slope and low lying areas debris slope was mapped with the highest accuracy while mps shows a low capability in mapping hogback and glacis the mapping accuracy is highest for training areas with a size of 7 5 10 of the total area reducing the size of the training images resulted in a decreased mapping quality as the frequency database only represents local characteristics of landforms that are not representative for the remaining area mps outperforms a rule based technique that only uses the morphometric attributes at the target mapping cell in the classification i e one point statistics technique by 15 of cell accuracy