lava flow identification and aging by means of lidar intensity mount etna case 1 an application of light detection and ranging lidar intensity for the identification and mapping of different lava flows from the mount etna italy active volcano is described in september 2004 an airborne lidar survey was flown over summit sectors of mount etna the information derived from lidar intensity values was used to compare the lava flows with respect to their age of emplacement analyzed lava flows vary in age between those dating prior to a d 1610 and those active during the survey 2004 2005 eruptions the target emitter distance as well as surface roughness and texture at the lidar footprint scale is the main parameter controlling the intensity response of lava flows variations in the roughness and texture of surfaces at a meter scale result from two main processes initial lava cooling and subsequent surface weathering both lead to variations in the original surface roughness of the flow in summary 1 initially from the time of emplacement the lidar intensity of lava flow surfaces decreases and 2 about 6 years after emplacement the lidar intensity of lava surfaces starts to increase with the age of flows lidar capability in terms of geometric accuracy of 1 m in plan position and less than 1 m in elevation and spectral lidar intensity depends on surface reflection at 1 064 m information can thus be effectively used to map lava flows and to define a relative chronology of lava emplacement

roughness of hawaiian volcanic terrains 1 we performed analyses of topographic variation surface roughness using a new 2 d mapping method which shows that understanding the relationship between data resolution hurst exponent y intercept rms deviation and cell size is important for assessing surface processes we use this new method to assess flows at six field sites in kilauea caldera hawaii using three data sets at different resolutions topsar 10 m pixel airborne lidar 1 m pixel and tripod mounted lidar 0 02 0 03 m pixel the flows studied include ponded pahoehoe flows compound pahoehoe flows and jumbled slabby pahoehoe the 2 d quantification of surface roughness for the kilauea lava flows indicates that features formed during emplacement and modification of the flows exhibit statistically distinct roughness signatures the 2 d method provides a tool for unit mapping based on surface roughness key findings indicate that the new 2 d method provides more robust results than 1 d methods for surface roughness because of larger 2 d sample sizes and the removal of 1 d directional bias leading to a reduction in error furthermore data set resolution relative to the scale of the features under study is important to consider when designing a 2 d surface roughness study future applications to topographic data sets from mars will provide information on flow emplacement conditions and spatial and temporal evolution of volcanic provinces on mars

quantifying fault zone activity in arid environments with high resolution topography 1 high resolution airborne laser swath mapping alsm topography illuminates active faulting with unprecedented clarity we contrast alsm topography of two dextral faults in arid regions of california with slip rates that differ by an order of magnitude the lenwood fault with rate of 1 mm yr and the clark fault a strand of the san jacinto fault with net slip rate 10 mm yr visualization of alsm data reveals abundant fault scarps and deflected channels that when reconstructed can yield powerful slip constraints though many of these features may also be detected in existing aerial photography these data are limited by stereo depth resolution and fixed illumination angle

on the prediction of channel heads in a complex alpine terrain using gridded elevation data 1 threshold conditions for channel initiation are evaluated by using gridded elevation data derived from a lidar survey a reliable algorithm for the determination of surface flow paths and field observations of channel heads for a study area located in the eastern italian alps these threshold conditions are determined by considering the channel heads observed across a portion of the study area and computing the related values of 1 drainage area a 2 area slope function as2 with s being the local slope and 3 strahler order of surface flow paths extracted from gridded elevation data attention is focused on the dependence of the obtained threshold values on the size of grid cells involved and on the ability of the identified threshold conditions to provide reliable predictions of channel heads across the entire study area the results indicate that the threshold values of a as2 and are all significantly dependent on grid cell size and the uncertainty in the determination of threshold values of is significantly smaller than that affecting the determination of threshold values of a and as2 the comparison between predicted and observed channel heads indicates that the considered methods display variable reliability and sensitivity over different drainage basins and grid cell sizes with a general tendency to predict more channel heads than can be observed in the field acceptable predictions are normally obtained where channel heads are formed essentially by surface runoff more comprehensive methods seem however to be needed to predict channel heads affected by groundwater seeping upward

evolution of channel morphology and hydrologic response in an urbanizing drainage basin the dead run catchment in baltimore county maryland has undergone intense urbanization since the late 1950s reconstruction of the channel planform from topographic maps dating back to the 1890s and aerial photographs dating back to the 1930s indicates that the channel has remained stable in planform since at least the 1930s the relative stability of dead run contrasts with the alterations in channel morphology reported for other urbanizing streams in the piedmont physiographic province of the eastern united states trend analyses of discharge records in dead run show that urban development and stormwater control measures have had significant impacts on the hydrologic response of the catchment the flood hydraulics of the dead run catchment are examined for the event that occurred on 22 june 1972 in association with hurricane agnes a two dimensional hydraulic model telemac 2d was used with a finite element mesh constructed from a combination of high resolution lidar topographic data and detailed field survey data to analyse the distribution of boundary shear stress and unit stream power along the channel and floodplain during flooding from hurricane agnes the spatial and temporal distributions of these parameters relative to channel gradient and channel valley bottom geometry provide valuable insights on the stability of the dean run channel the stability of dead run s channel planform in spite of extreme flooding and decades of urban development is most likely linked to geological controls of channel and floodplain morphology copyright 2006 john wiley sons ltd

landslide susceptibility revealed by lidar imagery and historical records seattle washington abstract light detection and ranging lidar data were used to visually map landslides headscarps and denuded slopes in seattle washington four times more landslides were mapped than by previous efforts that used aerial photographs the mapped landforms landslides headscarps and denuded slopes were created by many individual landslides the spatial distribution of mapped landforms and 1308 historical landslides show that historical landslide activity has been concentrated on the mapped landforms and that most of the landslide activity that created the landforms was prehistoric thus the spatial densities of historical landslides on the landforms provide approximations of the landforms relative susceptibilities to future landsliding historical landslide characteristics appear to be closely related to landform type so relative susceptibilities were determined for landslides with various characteristics no strong relations were identified between stratigraphy and landslide occurrence however landslide characteristics and slope morphology appear to be related to stratigraphic conditions human activity is responsible for causing about 80 of historical seattle landslides the distribution of mapped landforms and human caused landslides suggests the probable characteristics of future human caused landslides on each of the landforms the distribution of mapped landforms and historical landslides suggests that erosion of slope toes by surface water has been a necessary condition for causing seattle landslides human activity has largely arrested this erosion which implies that landslide activity will decrease with time as hillsides naturally stabilize however evaluation of glacial age analogs of areas of recent slope toe erosion suggests that landslide activity in seattle will continue for the foreseeable future

recent lahars at volcan de colima mexico drainage variation and spectral classification abstract volcan de colima is the most active volcano in mexico and represents a high risk for more than 500 000 people in 1998 the volcano renewed its activity with the extrusion of a lava dome and subsequent lava and block and ash flows during the recent period of activity pyroclastic products did not directly affect villages around the volcano however several lahars did we used lidar topographic coverage aster and landsat images for the recognition of morphological changes in the drainage system and lahar detection for lahar delineation we applied principal components analysis and canonical classification tasseled cap in order to perform a supervised image classification using the maximum likelihood rule algorithm laharz objective delineation of distal debris flow hazard zones has been used and tested using two topographic datasets with different resolutions which provided evidence of the importance of high resolution topographic coverage in hazard assessment finally a hazard map for lahars is presented showing that several villages and ranchos can be affected in contrast due to morphological changes produced by products of the intense explosive activity other populated areas such as la yerbabuena are outside of the high risk zone they could be affected by lahars only in case of cataclysmic eruptions such as the 1913 plinian event

using dinsar airborne lidar and archival air photos to quantify landsliding and sediment transport 1 we demonstrate the ability of coupled remote sensing tools to characterize large slow moving landslides in the eel river catchment northern california from a stack of alos interferograms we identified 5 large 1 km long landslides that exhibited significant activity from february 2007 to february 2008 for the boulder creek earthflow we used orthorectified air photos taken in 1964 and unfiltered airborne lidar flown in 2006 to map the displacement of trees growing on the landslide surface combining those displacement orientations with stacked dinsar data we observed average downslope velocities of 0 65 m yr 1 through the central transport zone of the landslide given landslide depth estimates minimum sediment transport and denudation rates are estimated to be 4100 m3 yr 1 and 1 6 mm yr 1 respectively our results demonstrate the highly erosive role of large slow moving landslides in landscape evolution and suggest that the superposition of dense ephemeral gully networks and rapidly moving zones within the landslide may facilitate delivery of slide mobilized sediment into adjacent fluvial channels

lidar derived morphology of the 1993 lascar pyroclastic flow deposits and implication for flow dynamics and rheology abstract pumice flows are potentially destructive volcanic events that derive from eruption column collapse and whose dynamics are poorly understood the challenges in studying these flows include the lack of constraints on the dynamics kinematics and initial conditions that control their emplacement we present a morphological study of the distal deposits lobes of the pumice flows resulting from the 1993 eruption at lascar chile the surface geometry of the lobes was measured in detail using a lidar device which allowed for detailed characterisation of their morphology consisting of central channel and lateral levees and terminal frontal snout in particular we find that the ratio of channel levee height as a function of the ratio of the distance between levees total width of the lobe has a characteristic curve for these pumice flow lobes our analysis of several of the lascar pumice lobe deposits south east sector identified several dimensionless groups of the available parameters which when compared against published results from both experimental and numerical investigations allowed us to constrain crucial kinematic and dynamic information on the terminal phase of the pumice flows notably we estimate the velocity of the terminal phase of pumice flows to be 5 10 m s froude numbers of 1 5 2 are comparable with values found for experimental granular flows height width aspect ratios for the levee channel section of the pumice lobes are similar to those for experimental flows although these same aspect ratios for the snout are much larger for the natural deposits than their small scale analogues finally we discuss the possible emplacement dynamics of the terminal lascar 1993 pumice flows a pseudo reynolds number based on the velocity estimation is found to be up to 100 times larger for the pumice flows than experimental scale flows this suggests that the flow retarding frictional forces for large scale flows are relatively unimportant compared to flows at smaller scales mechanical effects such as fluidisation mobilisation of material lying on the slopes over which they propagate and lubrication due to polydispersivity could provide an explanation for their ability to propagate on shallow slopes 6 11

airborne lidar in support of geomorphological and hydraulic modelling this paper considers the application of airborne laser altimetry lidar to the provision of elevation data at accuracies and spatial densities commensurate with the current generation of high resolution hydraulic models three sets of issues are addressed with reference to a telemac 2d model of a morphologically complex estuary in eastern england first the quality of airborne lidar data is assessed via multiscale calibration against surveyed sections and supplementary control points second image processing techniques are used for i identification of multiple regions of interest within large lidar mosaics ii subregional infilling of voids left by data drop outs iii filtering and subsampling to match topographic information content with model resolution and the density of the computational mesh third the implications of improved terrain data are considered with reference to the estimation of elevations and potential tidal volumes for a number of discrete flood compartments and the modelling of hypothetical inundation scenarios after minor offset correction to ensure registration with local benchmarks the quality of lidar elevation data within a 12 km x 4 kin coverage is found to be consistent with the published specification 0 10 to 0 15 m image processing tools provide an efficient means of managing information content and interfacing this with the gis based functionality of the preprocessing software used in conjunction with the hydraulic model the accuracy and spatial resolution of the lidar data allow the identification of subtle but important topographic variations between adjacent flood compartments in many cases differences in model results obtained using these data relative to previously estimated average flood compartment elevations are small importantly however lidar provides topographic information at an accuracy and resolution close to the present limits of model representation reliable representation of form allows the modeller to concentrate on the physical aspects of model parameterization whilst minimizing the conflation of parameter effects with those of poorly constrained geometric representation copyright c 2003 john wiley sons ltd

assessing the ability of airborne lidar to map river bathymetry airborne bathymetric lidar was collected for 220 river kilometers in the yakima and trinity river basins in the united states concomitant with the aerial data collection ground surveys of the river bed were performed in both basins we assess the quality of the bathymetric lidar survey from the perspective of its application toward creating accurate precise and complete streambed topography for numerical modeling and geomorphic assessment measurement error is evaluated with respect to ground surveys for magnitude and spatial variation analysis of variance statistics indicate that residuals from two independent ground surveys in similar locations do not come from the same population and that mean errors at different study locations also come from different populations systematic error indicates a consistent bias in the data and random error falls within values of expected precision

automated landslide mapping using spectral analysis and high resolution topographic data puget sound lowlands washington and portland hills oregon abstract landslide inventory maps are necessary for assessing landslide hazards and addressing the role slope stability plays in landscape evolution over geologic timescales however landslide inventory maps produced with traditional methods aerial photograph interpretation topographic map analysis and field inspection are often subjective and incomplete the increasing availability of high resolution topographic data acquired via airborne light detection and ranging lidar over broad swaths of terrain invites new automated landslide mapping procedures we present two methods of spectral analysis that utilize lidar derived digital elevation models of the puget sound lowlands washington and the tualatin mountains oregon to quantify and automatically map the topographic signatures of deep seated landslides power spectra produced using the two dimensional discrete fourier transform and the two dimensional continuous wavelet transform identify the characteristic spatial frequencies of deep seated landslide morphologic features such as hummocky topography scarps and displaced blocks of material spatial patterns in the amount of spectral power concentrated in these characteristic frequency bands highlight past slope instabilities and allow the delineation of landslide terrain when calibrated by comparison with detailed independently compiled landslide inventory maps our algorithms correctly classify an average of 82 of the terrain in our five study areas spectral analysis also allows the creation of dominant wavelength maps which prove useful in analyzing meter scale topographic expressions of landslide mechanics past landslide activity and landslide modifying geomorphic processes these results suggest that our automated landslide mapping methods can create accurate landslide maps and serve as effective objective and efficient tools for digital terrain analysis

multitemporal alsm change detection sediment delivery and process mapping at an active earthflow remote mapping and measurement of surface processes at high spatial resolution is among the frontiers in earth surface process research remote measurements that allow meter scale mapping of landforms and quantification of landscape change can revolutionize the study of landscape evolution on human timescales at mill gulch in northern california usa an active earthflow was surveyed in 2003 and 2007 by airborne laser swath mapping alsm enabling meter scale quantification of landscape change we calculate four year volumetric flux from the earthflow and compare it to long term catchment average erosion rates from cosmogenic radionuclide inventories from adjacent watersheds we also present detailed maps of changing features on the earthflow from which we can derive velocity estimates and infer dominant process these measurements rely on proper digital elevation model dem generation and a simple surface matching technique to align the multitemporal data in a manner that eliminates systematic error in either dataset the mean surface elevation of the earthflow and an opposite slope that was directly influenced by the earthflow decreased 14 1 mm yr from 2003 to 2007 by making the conservative assumption that these features were the dominant contributor of sediment flux from the entire mill gulch drainage basin during this time interval we calculate a minimum catchment averaged erosion rate of 0 30 0 02 mm yr analysis of beryllium 10 10be concentrations in fluvial sand from nearby russian gulch and the south fork gualala river provide catchment averaged erosion rates of 0 21 0 04 and 0 23 0 03 mm yr respectively from translated landscape features we can infer surface velocities ranging from 0 5 m yr in the wide upper source portion of the flow to 5 m yr in the narrow middle transport portion of the flow this study re affirms the importance of mass wasting processes in the sediment budgets of uplifting weak lithologies copyright 2011 john wiley sons ltd

suitability of lidar point density and derived landform curvature maps for channel network extraction this study uses landform curvature as an approach for channel network extraction we considered a study area located in the eastern italian alps where a high quality set of lidar data was available and where channel heads and related channel network were mapped in the field in the analysis we derived 1 m dtms from different ground lidar point densities and we used different smoothing factors for the landscape curvature calculation in order to test the suitability of the lidar point density and the derived curvature maps for the recognition of channel network this methodology is based on threshold values of the curvature calculated as multiples 1 3 times of the standard deviation of the curvature our analyses suggested that i the window size for curvature calculations has to be a function of the size of the features to be detected ii a coarse ground lidar point density could be as useful as a finer one for the recognition of main channel network features and iii rougher curvature maps are not optimal as they do not explore a sufficient range at which features occur while smoother curvature maps overcome this problem and are more appropriate for the extraction of surveyed channels copyright 2010 john wiley sons ltd

a physically based model of the effects of forest roads on slope stability 1 road networks in mountainous forest landscapes have the potential to increase the susceptibility to shallow landsliding by altering subsurface flow paths in this paper a road interception rerouting grid based model is developed and coupled with a hydrogeomechanical threshold based model for slope instability model results allow quantification of the influence of roads on shallow landsliding hazard across a landscape and generation of hypotheses about the broader geomorphic effect of roads the model is applied to three sites in northeastern italy to study the influence of three different procedures for upslope drainage area computation on model results the three procedures are a single flow direction procedure d8 a multiple flow direction procedure mf and an algorithm based on proportioning flow between two downslope pixels dinf model results are highly sensitive to upslope drainage area algorithm choice it is shown that d8 and mf are unsuitable for road impact evaluation due to grid bias d8 and excessive dispersion mf model implementation with the dinf procedure results in a reasonable compromise between the artifacts that characterize the other two algorithms observed landslide patterns are broadly consistent with model estimates a finding that underscores the utility of this simple approach for predicting the geomorphic effects of forest roads constructed on steep slopes the approach used in this study may be useful for defining criteria for road design that reduce the effects of roads on geomorphic processes

airborne laser swath mapping of the summit of erebus volcano antarctica applications to geological mapping of a volcano abstract the lidar observations reported here have provided the first high precision topographic data on the active craters of erebus volcano antarctica digital elevation data are invaluable for geomorphic analysis of volcanoes especially when combined with methods to automatically extract landscape features the data are indispensable for studying eruptive events and volcano tectonic processes airborne laser scanning or lidar is a rapidly emerging technology to map surface topography with high accuracy and detail comparable to a 1 1000 scale map in the austral summer of 2001 2002 airborne laser scanning data were collected in antarctica over the summit plateau of erebus volcano we describe the high resolution data set from erebus products derived from the data and demonstrate how extracted topographic features can be used in the geomorphic analysis of volcanoes background is presented on the airborne laser scanning method and on the accuracy estimation of laser points we describe the computation of a high resolution dem with a grid size of 2 m 2 m for the summit area of erebus volcano errors in the dem are assessed using independent ground based gps data and the rms error is estimated to be 0 39 m visualization methods reveal topographic features that are very useful for geomorphic analysis automatic feature extraction and processing is necessary to exploit the high resolution and accurate elevation data methods are described to extract 1d and 2d features and organize them for subsequent analysis fitting analytical functions to 3d point clouds or dems is particularly effective in extracting topographic features including planes higher order surfaces cones and conic sections these methods are used to obtain a quantitative description of the calderas and modern day crater of erebus especially valuable are the measured surface areas if the lava lakes as these control thermal emissions and gas fluxes from the volcano examination of the surface elevations of ray lava lake werner vent and active vent indicates that the active vents were more or less in magmastatic equilibrium in 2001 december conic segments are fitted to mapped sections of caldera rims to identify the sections buried under younger lava flows or covered by ice and snow automatic methods are used to detect and characterize lava channels using geomorphometric maps generated from the dem

measurement of river bank and cliff erosion from sequential lidar and historical aerial photography abstract the methodology and errors involved in determining the meander migration rates and amount of sediment produced by river bank and cliff erosion over five decades along a 16 and 28 km reach of the waipaoa river new zealand are described the reach average meander migration rates 0 22 and 0 12 m a 1 respectively are low by international standards for rivers of comparable size suggesting considerable stability of the river planform the contribution of sediment from bank and cliff erosion 74 3 and 23 3 kt a 1 respectively to suspended sediment load is also low

tracking and evolution of complex active landslides by multi temporal airborne lidar data the montaguto landslide southern italy abstract a multi temporal lidar study of an active landslide at montaguto italy is presented four lidar derived digital terrain models acquired on may 2006 july 2009 april 2010 and june 2010 are used the interpretation of selected morphometric parameters surface roughness residual topographic surface and the statistical analysis of the temporal variations of such parameters allowed the reconstruction and tracking of the landslide the landslide boundary monitoring was achieved and zones of uplift and subsidence volumes of removed and or accumulated material and average rates of vertical and horizontal displacement retreat rate of the crown and advancement rate of the toe were estimated deformation structures scarps cracks folds affecting the landslide in different times were also mapped some of such structures represent precursors of impending instability processes or give information on the mechanism of emplacement various types of activity e g rock fall flow and geometry e g channelized flow are recognized and zones whose topographic features change with time due to artificial drainage and earth handling removal work were detected the lidar derived information allows us to decipher the kinematics of the landslide the results provide new insight on the use of airborne lidar in the monitoring strategies of gravity controlled processes

morphometric analysis of lava flow units case study over lidar derived topography at mount etna italy abstract high resolution lidar derived digital elevation models of volcanic areas can significantly improve knowledge of lava flow morphology and emplacement mechanisms here we focus on single flow units presenting a new semi automatic procedure which provides a quantitative analysis of their shape the method relies on the automatic processing of the elevation profiles obtained on transects orthogonal to the flow unit axis the initial phase of the mount etna flank eruption from september 2004 is taken as test case and the procedure is applied on an active lava flow which was emplaced on the eastern flank of the volcano the main topographic dataset used is a 2 m resolution digital elevation model obtained from a lidar survey starting from the axis of a lava flow unit our method yields morphometric data on the flow unit at a 2 m spacing calculating parameters including flow width channel width the heights of the levees inward and outward slope of levees and estimating pre emplacement slope along the axis the procedure is embedded in a customized gis which allows easy processing handling and displaying of data the procedure has also been applied to another flow unit emplaced during the october november 1999 overflow from the bocca nuova crater results show that the channel width seems to accommodate first order trends of the pre emplacement slope along the flow unit axis while it is little affected by high frequency changes in slope in contrast flow unit width and flow unit thickness are apparently influenced by small scale changes in slope the different emplacement conditions of the two flow units are reflected by the overall contrasting morphologies as shown by the different average thickness and by the different ratios between i flow width vs channel width and ii flow unit section area vs channel width the new method provides an enhanced systematic and thorough morphometric description of flow units which may improve the understanding of the emplacement mechanisms of lava flows on earth and other planets

the changing face of mount etna s summit area documented with lidar technology 1986 2007 period amounts to 112 12 10 6 m 3 a t a mean annual rate of 5 3 10 6 m 3 the comparison of the various surveys furthermore emphasizes the levels of accuracy and resolution of the different techniques applied the lidar technology used in 2007 allows production of high precision maps in near real time facilitating work concerning environmental hazards such as numerical simulations of e g lava flows citation neri m f mazzarini s tarquini m bisson i isola b behncke and m t pareschi 2008 the changing face of mount etna s summit area documented with lidar technology geophys res lett 35 l09305 doi 10 1029 2008gl033740

object oriented identification of forested landslides with derivatives of single pulse lidar data in contrast to the many studies that use expert based analysis of lidar derivatives for landslide mapping in forested terrain only few studies have attempted to develop semi automatic methods for extracting landslides from lidar derivatives while all these studies are pixel based it has not yet been tested whether object oriented analysis ooa could be an alternative this study investigates the potential of ooa using only single pulse lidar derivatives such as slope gradient roughness and curvature to map landslides more specifically the focus is on both lidar data segmentation and classification of slow moving landslides in densely vegetated areas where spectral data do not allow accurate landslide identification a multistage procedure has been developed and tested in the flemish ardennes belgium the procedure consists of 1 image binarization and multiresolution segmentation 2 classification of landslide parts main scarps and landslide body segments and non landslide features i e earth banks and cropland fields with supervised support vector machines at the appropriate scale 3 delineation of landslide flanks 4 growing of a landslide body starting from its main scarp and 5 final cleaning of the inventory map the results obtained show that ooa using lidar derivatives allows recognition and characterization of profound morphologic properties of forested deep seated landslides on soil covered hillslopes because more than 90 of the main scarps and 70 of the landslide bodies of an expert based inventory were accurately identified with ooa for mountainous areas with bedrock on the other hand creation of a transferable model is expected to be more difficult

path based methods for the determination of nondispersive drainage directions in grid based digital elevation models 1 path based methods for the determination of nondispersive drainage directions in grid based digital elevation models are presented these methods extend the descriptive capabilities of the classical d8 method by cumulating the deviations between selected and theoretical drainage directions along the drainage paths it is shown that either angular or transversal deviations can be employed accordingly two classes of methods designated d8 lad eight drainage directions least angular deviation and d8 ltd eight drainage directions least transversal deviation are developed detailed tests on four synthetic drainage systems of known geometry and on the liro catchment central italian alps indicate that the proposed methods provide significant improvement over the d8 method for the determination of drainage directions and drainage areas

application of a multi temporal lidar derived digital terrain model in a landslide volume estimation sediments produced by landslides are crucial in the sediment yield of a catchment debris flow forecasting and related hazard assessment on a regional scale however it is difficult and time consuming to measure the volumes of such sediment this paper uses a lidar derived digital terrain model dtm taken in 2005 and 2010 at 2 m resolution to accurately obtain landslide induced sediment volumes that resulted from a single catastrophic typhoon event in a heavily forested mountainous area of taiwan the landslides induced by typhoon morakot are mapped by comparison of 25 cm resolution aerial photographs taken before and after the typhoon in an 83 6 km2 study area each landslide volume is calculated by subtraction of the 2005 dtm from the 2010 dtm and the scaling relationship between landslide area and its volume are further regressed the relationship between volume and area are also determined for all the disturbed areas vl 0 452al1 242 and for the crown areas of the landslides vl 2 510al1 206 the uncertainty in estimated volume caused by use of the lidar dtms is discussed and the error in absolute volume estimation for landslides with an area 105 m2 is within 20 the volume area relationship obtained in this study is also validated in 11 small to medium sized catchments located outside the study area and there is good agreement between the calculation from dtms and the regression formula by comparison of debris volumes estimated in this study with previous work it is found that a wider volume variation exists that is directly proportional to the landslide area especially under a higher scaling exponent copyright 2013 john wiley sons ltd

lidar derived dem evaluation of deep seated landslides in a steep and rocky region of japan abstract in steep and rocky terrains their rough surfaces make it difficult to create landslide inventories even with detailed maps images produced from airborne lidar data to provide objective clues in locating deep seated landslides the surface textures of a 5 km2 steepland area in japan was investigated using the eigenvalue ratio and slope filters calculated from a very high resolution lidar derived dem the range of filter values was determined for each of a number of surface features mapped in the field and these included cracked bedrock outcrops coarse colluvial deposits gently undulating surfaces and smooth surfaces recently active slides commonly contained patches of ground in which deposition and erosion occurred together near the erosion front or where cracked bedrock outcrops and coarse colluvial deposits coexisted under a gently undulating surface the characteristic eigenvalue and slope filter values representing this sliding process were applied to maps of the dem derived filter values to extract potential sites of recent landslide activity in addition the relationships between the filter values of deep seated landslides at various stages of evolution within the field mapped area were extended to the entire study area to assess the contribution that landslide evolution makes to change in the landscape as a whole while landslide components made up the steepest as well as the gentlest parts of the landscape depending on their evolutionary stage landslides were constantly coarsened and steepened by progressive erosion probably initiated by river bank erosion at the foot of slopes

range imaging a new method for high resolution topographic measurements in small and medium scale field sites topographic measurements are essential for the study of earth surface processes three dimensional data have been conventionally obtained through terrestrial laser scanning or photogrammetric methods however particularly in steep and rough terrain high resolution field measurements remain challenging and often require new creative approaches in this paper range imaging is evaluated as an alternative method for obtaining surface data in such complex environments range imaging is an emerging time of flight technology using phase shift measurements on a multi pixel sensor to generate a distance image of a surface its suitability for field measurements has yet not been tested we found ambient light and surface reflectivity to be the main factors affecting error in distance measurements low reflectivity surfaces and strong illumination contrasts under direct exposure to sunlight lead to noisy distance measurements however regardless of lighting conditions the accuracy of range imaging was markedly improved by averaging multiple images of the same scene for medium ambient lighting shade and a light coloured surface the measurement uncertainty was approximately 9 mm to further test the suitability of range imaging for field applications we measured a reach of a steep mountain stream with a horizontal resolution of approximately 1 cm in the focal plane of the camera allowing for the interpolation of a digital elevation model on a 2 cm grid comparison with an elevation model obtained from terrestrial laser scanning for the same site revealed that both models show similar degrees of topographic detail despite limitations in measurement range and accuracy particularly at bright ambient lighting range imaging offers three dimensional data in real time and video mode without the need of post processing therefore range imaging is a useful complement or alternative to existing methods for high resolution measurements in small to medium scale field sites copyright 2012 john wiley sons ltd

hillslope to valley transition morphology new opportunities from high resolution dtms abstract the search for the optimal spatial scale for observing landforms to understand physical processes is a fundamental issue in geomorphology topographic attributes derived from digital terrain models dtms such as slope curvature and drainage area provide a basis for topographic analyses the slope area relationship has been used to distinguish diffusive hillslope from linear valley processes and to infer dominant sediment transport processes in addition curvature is also useful in distinguishing the dominant landform process recent topographic survey techniques such as lidar have permitted detailed topographic analysis by providing high quality dtms this study uses lidar derived dtms with a spatial scale between 1 and 30 m in order to find the optimal scale for observation of dominant landform processes in a headwater basin in the eastern italian alps where shallow landsliding and debris flows are dominant the analysis considered the scaling regimes of local slope versus drainage area the spatial distribution of curvature and field observations of channel head locations the results indicate that i hillslope to valley transitions in slope area diagrams become clearer as the dtm grid size decreases due to the better representation of hillslope morphology and the topographic signature of valley incision by debris flows and landslides is also best displayed with finer dtms ii regarding the channel head distribution in the slope area diagrams the scaling regimes of local slope versus drainage area obtained with grid sizes of 1 3 and 5 m are more consistent with field data and iii the use of thresholds of standard deviation of curvature particularly at the finest grid size were proven as a useful and objective methodology for recognizing hollows and related channel heads

tectonic geomorphology of the san andreas fault zone from high resolution topography an example from the cholame segment abstract high resolution topographic data along fault zones are important aids in the delineation of recently active breaks a 15 km long portion of the south central san andreas fault saf along the southern cholame segment contains well preserved tectonic landforms such as benches troughs scarps and aligned ridges that indicate recurring earthquake slip recently acquired lidar topographic data along the entire southern saf b4 project have shot densities of 3 4 m 2 computed from the lidar returns digital elevation models dems of 0 25 to 0 5 m resolution using local binning with inverse distance weighting and 0 8 m or larger search radii depict the tectonic landforms at paleoseismic sites well enough to assess them confidently mapping of recently active breaks using a lidar only based approach compares well with aerial photographic and field based methods the fault zone varies in width from meters to nearly 1 km and is comprised of numerous en echelon meter to kilometer length overlapping sub parallel fault surfaces bounding differentially moving blocks that elongate parallel to the saf the semantic variations of what constitutes active and the importance of secondary traces influence the breadth and complexity of the resulting fault trace maps

on the global gravity field and plate kinematics abstract in this paper we investigate the relation between the geopotential as represented by low order harmonics and present plate kinematics using coordinates connected to the poles of absolute plate motion we demonstrate certain systematics of the geoid along and across the trajectories of the eight major plates pac afr ind eur nam sam ant and naz although the systematics varies from plate to plate this variation is not arbitrary but is related to additional parameters such as the magnitude of absolute velocity the occurrence of subduction and the existence of continents on the plates our main conclusion is that the low order geoid is related dominantly to two phenomena to current subduction and to the past pangea or in other words to a flow field that has accompanied or has caused the break up of pangea such a conclusion is of course speculative and requires much further investigation

slip in the 1857 and earlier large earthquakes along the carrizo plain san andreas fault the moment magnitude mw 7 9 fort tejon earthquake of 1857 with a 350 kilometer long surface rupture was the most recent major earthquake along the south central san andreas fault california based on previous measurements of its surface slip distribution rupture along the 60 kilometer long carrizo segment was thought to control the recurrence of 1857 like earthquakes new high resolution topographic data show that the average slip along the carrizo segment during the 1857 event was 5 3 1 4 meters eliminating the core assumption for a linkage between carrizo segment rupture and recurrence of major earthquakes along the south central san andreas fault earthquake slip along the carrizo segment may recur in earthquake clusters with cumulative slip of 5 meters

high resolution dems in the study of rainfall and earthquake induced landslides use of a variable window size method in digital terrain analysis abstract we undertake digital terrain analyses of rainfall and earthquake induced landslides in japan using high resolution orthoimagery and light detection and ranging lidar dems our aims are twofold to demonstrate an effective method for dealing with high resolution dems which are often too detailed for landslide assessments and to evaluate the topographic differences between rainfall and earthquake induced landslides the study areas include the izumozaki 1961 and 2004 heavy rainfalls niihama 2004 heavy rainfalls houfu 2009 heavy rainfalls and hanokidachi kurikoma dam regions the 2008 m 7 2 iwate miyagi nairiku earthquake the study areas include 7 106 landslides in these five regions we use two topographic attributes the slope gradient and the laplacian calculated from dems in varying window sizes the hit rates for statistical prediction of landslide cells through discriminant analyses are calculated using the two topographic attributes as explanatory variables and the landslide inventory data as the dependent variable in cases of surface failure the hit rates are found to diminish when the window size of the topographic attributes is too large or too small indicating that an optimal scale factor is key in assessing shallow landslides the representative window sizes are approximately 30 m for shallow landslides the optimal window size may be directly related to the average size of landslides in each region we also find a stark contrast between rainfall and earthquake induced landslides rainfall induced landslides are always most common at a slope gradient of 30 but the frequency of earthquake induced landslides increases exponentially with slope gradient we find that the laplacian i e the attributes of surface convexity and concavity and the slope gradient are both important factors for rainfall induced landslides whereas earthquake induced landslides are influenced mainly by slope steepness

landslide inventory maps new tools for an old problem landslides are present in all continents and play an important role in the evolution of landscapes they also represent a serious hazard in many areas of the world despite their importance we estimate that landslide maps cover less than 1 of the slopes in the landmasses and systematic information on the type abundance and distribution of landslides is lacking preparing landslide maps is important to document the extent of landslide phenomena in a region to investigate the distribution types pattern recurrence and statistics of slope failures to determine landslide susceptibility hazard vulnerability and risk and to study the evolution of landscapes dominated by mass wasting processes conventional methods for the production of landslide maps rely chiefly on the visual interpretation of stereoscopic aerial photography aided by field surveys these methods are time consuming and resource intensive new and emerging techniques based on satellite airborne and terrestrial remote sensing technologies promise to facilitate the production of landslide maps reducing the time and resources required for their compilation and systematic update in this work we first outline the principles for landslide mapping and we review the conventional methods for the preparation of landslide maps including geomorphological event seasonal and multi temporal inventories next we examine recent and new technologies for landslide mapping considering i the exploitation of very high resolution digital elevation models to analyze surface morphology ii the visual interpretation and semi automatic analysis of different types of satellite images including panchromatic multispectral and synthetic aperture radar images and iii tools that facilitate landslide field mapping next we discuss the advantages and the limitations of the new remote sensing data and technology for the production of geomorphological event seasonal and multi temporal inventory maps we conclude by arguing that the new tools will help to improve the quality of landslide maps with positive effects on all derivative products and analyses including erosion studies and landscape modeling susceptibility and hazard assessments and risk evaluations

high resolution interpretative geomorphological mapping of river valley environments using airborne lidar data the availability of airborne lidar data provides a new opportunity to overcome some of the problems associated with traditional field based geomorphological mapping such as restrictions on access and constraints of time or cost the combination of airborne lidar data and gis technology facilitates the rapid production of geomorphological maps of floodplain environments however unfiltered lidar data which include vegetation and buildings are currently more suitable for geomorphological mapping than data that have been filtered to remove these features classification of lidar data according to elevation in a gis enables the user to identify and delineate geomorphological features in a manner similar to field mapping but it is necessary to use a range of classification intervals in order to map the various types of feature that occur within a single reach comparison of a lidar derived geomorphological map with an independently produced field geomorphological map showed a high degree of similarity between the results of the two methods although ground truthing is essential in cases where a high degree of accuracy is required ground truthing of a lidar derived geomorphological map showed that around 80 of features mapped using both methods were identified from the lidar data suggesting that the method is suitable for applications such as production of base maps for use in field mapping and selection of sites for detailed investigation copyright 2007 john wiley sons ltd

changes in the water surface profile of the colorado river in grand canyon arizona between 1923 and 2000 1 in 1923 a u s geological survey expedition surveyed the water surface profile of the colorado river through grand canyon with theodolite and stadia rod in 2000 lidar overflights collected topographic data centered on the river corridor allowing construction of a new water surface profile and detection of change in the profile since 1923 by registering the surveys with respect to each other on the basis of 11 locations that were independently determined to have been unchanged between 1923 and 2000 80 rapids were directly compared for change between 1923 and 2000 the average change for all measured rapids was 0 26 m indicating net aggradation of the coarse grained alluvium forming the rapids throughout grand canyon in addition comparison of the two water surface profiles showed enhanced pool and rapid morphology while 50 of the total drop of the river occurred in just 9 of the river distance in 1923 that value increased to 66 by 2000

application of high resolution dem data to detect rock damage from geomorphic signals along the central san jacinto fault abstract we analyze geomorphic properties extracted from lidar and srtm shuttle radar topography mission data to test whether the damage zone along the central san jacinto fault sjf zone can be resolved with remotely sensed data in a quantitative fashion the sjf is one of the most active faults in southern california with well expressed geomorphology and a fast slip rate as seen in the geology and by gps we use arcmap and the taudem toolbox to compare several morphometric parameters including drainage density dd on both sides of the fault using a 1 km and a 5 km buffer for the lidar and srtm data respectively we also analyze the spatial patterns of dd near the fault using two different definitions of spatial dd the high resolution of the lidar data allows us to focus on a single fault eliminating the effects of parallel nearby faults from the lidar data we find that the highest dd values occur in areas between two fault strands followed generally by rocks on the northeast side of the fault with the lowest dd values occurring on the southwest side of the fault the srtm data shows a band of high dd values centered on the main fault trace with 1 km width our results indicate that there is a strong correlation between drainage density and proximity to the fault with zones of structural complexity along the fault displaying the highest dd we interpret this to largely be an effect of degree of rock damage as these are areas that are expected to be more damaged and field observations support this contention if we are correct then it appears that the northeast side of the sjf is generally more damaged south of the trifurcation area there is evidence that the signal is reversed on the larger scale with more damage on the southwest side of the fault inferred from the srtm data possibly caused by extension between the coyote creek and clark faults the implications of the observed asymmetry could be geological evidence for rupture propagation direction because a preferred propagation direction is predicted to produce asymmetric damage structure that would be recorded in the volume of rock surrounding a fault

recognition of large scale deep seated landslides in forest areas of taiwan using high resolution topography abstract large deep seated landslides can be reactivated during intense events and they can evolve into destructive failures they are generally difficult to recognize in the field especially when they develop in densely forested areas a detailed and constantly updated inventory map of such phenomena and the recognition of their topographic signatures is absolutely a key tool for landslide risk mitigation the aim of this work is to test in forested areas the performance of the new automatic and objective methodology developed by tarolli et al 2012 for geomorphic features extraction landslide crowns from high resolution topography lidar derived digital terrain models dtms the methodology is based on the detection of landslides through the use of thresholds obtained by the statistical analysis of variability of landform curvature the study was conducted in a high risk area located in the central south taiwan where an accurate field survey on landsliding processes and a high quality set of airborne laser scanner elevation data are available the area has been chosen because some of the deep seated landslides are located near human infrastructures and their reactivation is highly dangerous thanks to lidar s capability to detect the bare ground elevation data in forested areas it was possible to recognize in detail landslide features also in remote regions difficult to access the results if compared with the previous work of tarolli et al 2012 mainly focused on shallow landslides and in a not forested area indicate that for deep seated landslides where the crowns are more evident and they are present at large scale the tested methodology performs better higher quality index the method can be used to interactively assist the interpreter user on the task of deep seated landslide hazard mapping and risk assessment planning of such regions

high resolution topography for understanding earth surface processes opportunities and challenges abstract in the last decade a range of new remote sensing techniques has led to a dramatic increase in terrain information providing new opportunities for a better understanding of earth surface processes based on geomorphic signatures technologies such as airborne and terrestrial lidar light detection and ranging to obtain high resolution topography have opened avenues for the analysis of landslides hillslope and channellization processes river morphology active tectonics volcanic landforms and anthropogenic signatures on topography this review provides an overview of the recent flourishing literature on high resolution topographic analyses underlining their opportunities and critical issues such as their limitations the goal is to provide answers to questions such as what kind of processes can be analyzed through high resolution topographic data and how to do it the review focuses on two different environments natural and engineered landscapes in both contexts high resolution topography offers opportunities to better understand geomorphic processes from topographic signatures particular attention is given to engineered landscapes in which the direct anthropic alteration of processes is significant the last part of the review discusses future challenges

characterizing the hsincheng active fault in northern taiwan using airborne lidar data detailed geomorphic features and their structural implications abstract we applied newly acquired high resolution airborne lidar data to study a segment of the hsincheng fault a well known active fault near a large industrial park in northern taiwan the hsincheng fault has received much attention and study in the past but high spatial resolution digital elevation models have not previously been applied to the study of the fault and its surrounding structures we processed the acquired lidar data and produced 1 m digital elevation models dems to investigate the active fault adjacent to the densely populated and important infrastructure in taiwan using the lidar dems aerial photographs and topographic maps we show highly detailed geomorphic characteristics around the study area of the hsincheng fault three major characteristics of the study area are defined that include three very well preserved river terraces at varying levels the fault fold scarp of the hsincheng fault and meandering river systems using the lidar dems we were able to detect with precision several fault fold scarps and very gentle ne trending folding of the river terraces in general the lidar dems have provided unprecedented clarity of landforms for one segment of the hsincheng fault which has helped the characterization of subtle but important geomorphic features

scaling regimes of local slope versus contributing area in digital elevation models four scaling regimes are observed in digital elevation models dems when the average local slope is calculated for pixels grouped according to the values of the contributing area threshold criteria proposed by various researchers to identify the extent of the channel network are examined relative to the slope area scaling diagram the scaling response observed in dems is reproduced with a landscape evolution and channel network growth model originally developed by willgoose et al 1989 the threshold criterion proposed in this model is a useful tool to separate two different slope area scaling regimes observed in dem data

detecting short term evolution of etnean scoria cones a lidar based approach the 2001 and 2002 2003 flank eruptions on mount etna italy were characterized by intense explosive activity which led to the formation of two large monogenetic scoria cones one from each eruption on the upper southern flank of the volcano continuous monitoring of etna especially during flank eruptions has provided detailed information on the growth of these cones they differ in genesis shape and size a set of high resolution 1 m digital elevation models dems derived from light detection and ranging lidar data collected during four different surveys 2004 2005 2006 and 2007 has been used to map morphology and to extract the morphometric parameters of the scoria cones by comparing lidar derived dems with a pre eruption 1998 10 m dem the volume of the two scoria cones was calculated for the first time comparison of the lidar derived dems revealed in unprecedented detail morphological changes during scoria cone degradation in particular the morphologically more exposed and structurally weaker 2002 2003 cone was eroded rapidly during the first few years after its emplacement mainly due to gravitational instability of slopes and wind erosion

unusually low rates of slip on the santa rosa range fault zone northern nevada the santa rosa range fault zone srrfz is one of the most topographically prominent normal fault systems in the northern basin and range province of the western united states it has been assigned high rates of vertical slip by others and has been identified as a possible site of the future extension of the central nevada seismic belt cnsb we use detailed trench mapping and luminescence dating to estimate displacements and timing of the last several large magnitude paleoearthquakes on the southern part of the srrfz at a trench site near orovada nevada coseismic vertical displacements ranged from 1 to 2 8 m for each of the last four events luminescence ages provide time limits for the last three events of 125 155 ka 90 108 ka and 11 16 ka these data yield recurrence intervals of 17 65 k y and 74 97 k y and an elapsed time of 11 16 k y since the youngest event slip rate determinations at the orovada site are complicated by multiple fault strands but rates calculated from a variety of data are surprisingly low 0 01 0 16 mm yr given the topographic prominence of the santa rosa range a lack of compelling patterns in a comparison of paleoseismic parameters indicate that the srrfz is no more likely a location for a large magnitude earthquake than previously identified seismic gaps or along faults that lie directly north of the cnsb

automatic geomorphic feature extraction from lidar in flat and engineered landscapes 1 high resolution topographic data derived from light detection and ranging lidar technology enables detailed geomorphic observations to be made on spatially extensive areas in a way that was previously not possible availability of this data provides new opportunities to study the spatial organization of landscapes and channel network features increase the accuracy of environmental transport models and inform decisions for targeting conservation practices however with the opportunity of increased resolution topographic data come formidable challenges in terms of automatic geomorphic feature extraction analysis and interpretation low relief landscapes are particularly challenging because topographic gradients are low and in many places both the landscape and the channel network have been heavily modified by humans this is especially true for agricultural landscapes which dominate the midwestern united states the goal of this work is to address several issues related to feature extraction in flat lands by using geonet a recently developed method based on nonlinear multiscale filtering and geodesic optimization for automatic extraction of geomorphic features channel heads and channel networks from high resolution topographic data here we test the ability of geonet to extract channel networks in flat and human impacted landscapes using 3 m lidar data for the le sueur river basin a 2880 km 2 subbasin of the minnesota river basin we propose a curvature analysis to differentiate between channels and manmade structures that are not part of the river network such as roads and bridges we document that laplacian curvature more effectively distinguishes channels in flat human impacted landscapes compared with geometric curvature in addition we develop a method for performing automated channel morphometric analysis including extraction of cross sections detection of bank locations and identification of geomorphic bankfull water surface elevation using the slope plotted along each channel floodplain cross section we demonstrate the ability to identify and measure the height of river banks and bluffs finally we present an example that demonstrates how extracting such features automatically is important for modeling channel evolution water and sediment transport and channel floodplain sediment exchange

the effectiveness of hillshade maps and expert knowledge in mapping old deep seated landslides large deep seated landslides with a shear surface deeper than 3 m and a mean affected area of 4 2 ha are common features in the flemish ardennes none of these deep seated landslides are dated but they are assumed to be rather old 100 years because most of these landslides are located under forest aerial photo interpretation commonly used for the creation of landslide inventories is not a suitable tool to map the landslides in the flemish ardennes therefore an intensive 100 day field survey was carried out by two geomorphologists in a 430 km 2 study area this resulted in a landslide inventory map indicating the location of 135 large deep seated landslides but field surveys are time consuming and thus very expensive therefore a cheaper and faster mapping technique was tested a hillshade map was constructed for the study area in a gis idris132 from a 5 m resolution digital elevation model dem seven experts were given 1 h to indicate all the hillslope sections which they suspected to be possible landslides on a copy of the aforementioned map scale 1 100 000 in total this exercise took only 1 day i e 7 person hours large differences in the number of presumed landslides and the extent of the hillslopes thought to be affected by landslides were reported among the seven experts the polygon and pixel efficiency were introduced to estimate the quality of the landslide maps based on hillshade maps and expert knowledge compared to the field survey based landslide inventory the quality of the landslide inventories based on the hillshade maps and expert knowledge was relatively low experts familiar with the study area obtained somewhat better results than experts who visited the study area only once a combination of the seven expert maps did not result in a good inventory map because too many unaffected hillslopes were incorrectly indicated as affected by landslides the results obtained in this study are comparable to an investigation carried out by wills c j mccrink t p 2002 comparing landslide inventories the map depends on the method environmental and engineering geoscience 8 279 293 although the tested method can never replace a detailed field survey taking into account the proposed improvements it can be used for the creation of a regional inventory map of old landslides in a densely forested area where light detection and ranging lidar data are unavailable c 2004 elsevier b v all rights reserved

mapping and downflow simulation of recent lava flow fields at mount etna in recent years progress in geographic information systems gis and remote sensing techniques have allowed the mapping and studying of lava flows in unprecedented detail a composite gis technique is introduced to obtain high resolution boundaries of lava flow fields this technique is mainly based on the processing of lidar derived maps and digital elevation models dems the probabilistic code downflow is then used to simulate eight large flow fields formed at mount etna in the last 25 years thanks to the collection of 6 dems representing mount etna at different times from 1986 to 2007 simulated outputs are obtained by running the downflow code over pre emplacement topographies simulation outputs are compared with the boundaries of the actual flow fields obtained here or derived from the existing literature although the selected fields formed in accordance with different emplacement mechanisms flowed on different zones of the volcano over different topographies and were fed by different lava supplies of different durations downflow yields results close to the actual flow fields in all the cases considered this outcome is noteworthy because downflow has been applied by adopting a default calibration without any specific tuning for the new cases considered here this extensive testing proves that if the pre emplacement topography is available downflow yields a realistic simulation of a future lava flow based solely on a knowledge of the vent position in comparison with deterministic codes which require accurate knowledge of a large number of input parameters downflow turns out to be simple fast and undemanding proving to be ideal for systematic hazard and risk analyses

a fault scarp in an urban area identified by lidar survey a case study on the itoigawa shizuoka tectonic line central japan abstract a light detection and ranging lidar survey was conducted in a densely built up area to generate a high resolution digital elevation model dem to look for active faults the urban district of matsumoto city in central japan is located in a 3 km 2 basin along the itoigawa shizuoka tectonic line active fault system one of japanese onshore fault systems with the highest earthquake probability a high resolution dem at a 0 5 m grid interval was obtained after removing the effects of laser returns from buildings clouds and vegetation it revealed a continuous scarp up to 2 m in height borehole data and archaeological studies indicate the scarp was formed during the most recent faulting event associated with historical earthquakes in addition the fault scarp strongly supports that the urban district is in a pull apart basin related to a fault step over between two left lateral strike slip faults consequently accurate interpretation of fault geometry is crucial to provide estimates of future surface deformation and to allow modeling of basin structure and strong ground motion thus the lidar mapping survey in urban districts is effective for detailed active fault mapping in order to constrain basin structure and to forecast the exact location of surface rupturing associated with large earthquakes

lidar and field observations of slip distribution for the most recent surface ruptures along the central san jacinto fault we measured offsets on tectonically displaced geomorphic features along 80 km of the clark strand of the san jacinto fault sjf to estimate slip per event for the past several surface ruptures we identify 168 offset features from which we make over 490 measurements using b4 light detection and ranging lidar imagery and field observations our results suggest that lidar technology is an exemplary supplement to traditional field methods in slip per event studies displacement estimates indicate that the most recent surface rupturing event mre produced an average of 2 5 2 9 m of right lateral slip with maximum slip of nearly 4 m at anza a m w 7 2 7 5 earthquake average multiple event offsets for the same 80 kms are 5 5 m with maximum values of 3 m at anza for the penultimate event cumulative displacements of 9 10 m through anza suggest the third event was also similar in size paleoseismic work at hog lake dates the most recent surface rupture event at ca 1790 a poorly located large earthquake occurred in southern california on 22 november 1800 we relocate this event to the clark fault based on the mre at hog lake we also recognize the occurrence of a younger rupture along 15 20 km of the fault in blackburn canyon with 1 25 m of average displacement we attribute these offsets to the 21 april 1918 m w 6 9 event these data argue that much or all of the clark fault and possibly also the casa loma fault fail together in large earthquakes but that shorter sections may fail in smaller events online material topographic contour maps and hillshades generated from b4 lidar data corresponding field photographs and data tables comparing lidar based and field based slip measurements for individual geomorphic features along the clark fault

airborne laser scanning of forested landslides characterization terrain model quality and visualization abstract mapping complex landslides under forested terrain requires an appropriate quality of digital terrain models dtms which preserve small diagnostic features for landslide classification such as primary and secondary scarps cracks and displacement structures flow type and rigid type optical satellite imagery aerial photographs and synthetic aperture radar images are less effective to create reliable dtms under tree coverage here we utilized a very high density airborne laser scanning als data with a point density of 140 points m 2 for generating a high quality dtm for mapping landslides in forested terrain in the barcelonnette region the southern french alps we quantitatively evaluated the preservation of morphological features and qualitatively assessed the visualization of als derived dtms we presented a filter parameterization method suitable for landslide mapping and compared it with two default filters from the hierarchical robust interpolation hri and one default filter from the progressive tin densification ptd method the results indicate that the vertical accuracy of the dtm derived from the landslide filter is about 0 04 m less accurate than that from the ptd filter however the landslide filter yields a better quality of the image for the recognition of small diagnostic features as depicted by expert image interpreters several dtm visualization techniques were compared for visual interpretation the openness map visualized in a stereoscopic model reveals more morphologically relevant features for landslide mapping than the other filter products we also analyzed the minimal point density in als data for landslide mapping and found that a point density of more than 6 points m 2 is considered suitable for a detailed analysis of morphological features this study illustrates the suitability of high density als data with an appropriate parameterization for the bare earth extraction used for landslide identification and characterization in forested terrain

application of airborne lidar to mapping seismogenic faults in forested mountainous terrain southeastern alps slovenia results are presented of the first airborne lidar survey ever flown in europe for the purpose of mapping the surface expression of earthquake prone faults detailed topographic images derived from lidar data of the idrija and ravne strike slip faults in nw slovenia reveal geomorphological and structural features that shed light on the overall architecture and kinematic history of both fault systems the 1998 mw 5 6 and 2004 mw 5 2 ravne fault earthquakes and the historically devastating 1511 m 6 8 idrija earthquake indicate that both systems pose a serious seismic hazard in the region because both fault systems occur within forested terrain a tree removal algorithm was applied to the data the resulting images reveal surface scarps and tectonic landforms in unprecedented detail importantly two sites were discovered to be potentially suitable for fault trenching and palaeo seismological analysis this study highlights the potential contribution of lidar surveying in both low relief valley terrain and high relief mountainous terrain to a regional seismic hazard assessment programme geoscientists working in other tectonically active regions of the world where earthquake prone faults are obscured by forest cover would also benefit from lidar maps that have been processed to remove the canopy return and reveal the forest floor topography

in situ characterization of grain scale fluvial morphology using terrestrial laser scanning the grain scale morphology of fluvial sediments is an important control on the character and dynamics of river systems however current understanding of its role is limited by the difficulties of robustly quantifying field surface morphology terrestrial laser scanning tls offers a new methodology for the rapid acquisition of high resolution and high precision surface elevation data from in situ sediments to date most environmental and fluvial applications of tls have focused on large scale systems capturing macroscale morphologies application of this new technology at scales necessary to characterize the complexity of grain scale fluvial sediments therefore requires a robust assessment of the quality and sources of errors in close range tls data this paper describes both laboratory and field experiments designed to evaluate close range tls for sedimentological applications and to develop protocols for data acquisition in the former controlled experiments comprising high resolution scans of white grey and black planes and a sphere were used to quantify the magnitude and source of three dimensional 3d point errors resulting from a combination of surface geometry reflectivity effects and inherent instrument precision subsequently a methodology for the collection and processing of grain scale tls data is described through an application to a coarse grained gravel system the river feshie d50 32 to 63 mm this stepwise strategy incorporates averaging repeat scans and filtering scan artefact and non surface points using local 3d search algorithms the sensitivity of the results to the filter parameter values are assessed by careful internal validation of digital terrain models dtms created from the resulting point cloud data the transferability of this methodology is assessed through application to a second river bury green brook dominated by finer gravel d50 18 to 33 mm the factor limiting the resolution of dtms created from this second dataset was found to be the relative sizes of the laser footprint and smallest grains copyright 2009 john wiley sons ltd

geomorphic response to uplift along the dragon s back pressure ridge carrizo plain california we used high resolution topography geomorphic mapping of active surface processes and geologic mapping to study the topographic and erosional response of small drainage basins to rock uplift along the dragon s back pressure ridge along the san andreas fault in the carrizo plain california we infer the history of deformation experienced by 40 small drainage basins formed in poorly consolidated sedimentary rocks a space for time substitution directly images the erosional and topographic responses to deformation progressive deformation and rock uplift are accompanied by increases in channel steepness and basin relief as uplift ceases channel concavity rapidly increases causing channels to undercut hillslopes this undercutting promotes the consumption of hillslopes by landsliding this undercutting also causes basin relief to be greatest after uplift has stopped this analysis indicates that channels of the dragon s back pressure ridge respond to changes in rock uplift rates over thousands of years whereas hillslope processes may take more than an order of magnitude longer to adjust to changes in rock uplift rates our study directly measures changes in erosional processes due to the initiation and cessation of rock uplift which can typically only be inferred using numerical models by direct field observations

supervised landform classification of northeast honshu from dem derived thematic maps this paper proposes a quantitative method to classify landforms using four morphometric parameters from dem derived thematic raster maps of slope and topographic openness because the different surficial processes and stages in the evolution of slopes create landscapes with different shapes these parameters may lead to a genetic interpretation of topography the raster maps of slope and topographic openness were constructed for northeast honshu japan from 50 m dems the mean and standard deviation of morphometric parameters within a 3050m by 3050m moving window on the raster maps were calculated the results for some training areas show that constructional depositional and erosional landforms with different relief have different morphometric characteristics a supervised landform classification for northeast honshu using the knowledge from the training areas revealed a ladder geomorphological structure composed of high mountains ranges and volcanoes the close relationship between the ladder geomorphological structure and volcano distribution indicates that the structure reflects the magmatic plumbing system from the upper mantle to the crust of the northeast honshu arc

structure from motion photogrammetry a low cost effective tool for geoscience applications abstract high resolution topographic surveying is traditionally associated with high capital and logistical costs so that data acquisition is often passed on to specialist third party organisations the high costs of data collection are for many applications in the earth sciences exacerbated by the remoteness and inaccessibility of many field sites rendering cheaper more portable surveying platforms i e terrestrial laser scanning or gps impractical this paper outlines a revolutionary low cost user friendly photogrammetric technique for obtaining high resolution datasets at a range of scales termed structure from motion sfm traditional softcopy photogrammetric methods require the 3 d location and pose of the camera s or the 3 d location of ground control points to be known to facilitate scene triangulation and reconstruction in contrast the sfm method solves the camera pose and scene geometry simultaneously and automatically using a highly redundant bundle adjustment based on matching features in multiple overlapping offset images a comprehensive introduction to the technique is presented followed by an outline of the methods used to create high resolution digital elevation models dems from extensive photosets obtained using a consumer grade digital camera as an initial appraisal of the technique an sfm derived dem is compared directly with a similar model obtained using terrestrial laser scanning this intercomparison reveals that decimetre scale vertical accuracy can be achieved using sfm even for sites with complex topography and a range of land covers example applications of sfm are presented for three contrasting landforms across a range of scales including an exposed rocky coastal cliff a breached moraine dam complex and a glacially sculpted bedrock ridge the sfm technique represents a major advancement in the field of photogrammetry for geoscience applications our results and experiences indicate sfm is an inexpensive effective and flexible approach to capturing complex topography

use of lidar derived images for mapping old landslides under forest large deep seated landslides are common features in the flemish ardennes belgium as most of these old 100 years landslides are located under forest in this hilly region aerial photograph interpretation is not an appropriate landslide mapping method this study tested the potential of lidar light detection and ranging images for mapping old landslides under forest landslide inventory maps were created for a 125 km2 area by applying the expert knowledge of seven geomorphologists to lidar derived hillshade slope and contour line maps in a gis environment each of the seven lidar based landslide inventories was compared i with the other six ii with a detailed field survey based inventory and iii with a comparable study in which topographic data were extracted from a topographical map the combination of the percentage of field landslides indicated by an expert and the percentage of positional discrepancies expressed in terms of positional mismatch were used to evaluate the quality of the lidar based inventory maps high quality lidar derived landslide inventory maps contain more than 70 per cent of the landslides mapped during the field survey and have positional discrepancies smaller than 70 per cent when compared with the field survey based inventory map four experts and the combination map of all experts satisfied these criteria together the seven experts indicated all landslides mapped in the field importantly lidar enabled the experts to find ten new landslides and to correct the boundaries of eleven of the 77 landslides mapped during the field survey hence this study showed that large scale lidar derived maps analysed by experienced geomorphologists can significantly improve field survey based inventories of landslides with a subdued morphology in hilly regions copyright 2006 john wiley sons ltd

emplacement mechanism of gravity flows inferred from high resolution lidar data the 1944 somma vesuvius lava flow italy abstract a digital terrain model derived from high resolution lidar data allows the determination of the morphometric and physical parameters of a lava flow erupted from the somma vesuvius volcano in 1944 the downstream variation of morphometric parameters including slope aspect relative relief thickness width and cross sectional area is analyzed and the changes in viscosity velocity and flow rate are estimated the aims of the analyses are to recognize different flow surfaces to reconstruct the flow kinematics and to obtain information on the mechanism of emplacement the results indicate that the 1944 lava flow can be divided in three sectors a near vent sector nvs characterized by a toe like surface an intermediate sector is with an a type brittle surface and a distal sector ds with a sheet like ductile surface lateral levees and channels do not occur in nvs whereas they are well developed in is in ds levees increase with an increasing distance from the vent fold like surfaces occur in nvs and ds reflecting local shortening processes due to a decrease in the slope of the substratum and overflows from the main channel is and ds emplaced between march 18 and 21 1944 whereas nvs emplaced on march 19 and partly covered is the morphometric and physical parameters indicate that is moved in a tube like regime whereas ds emplaced in a mobile crust regime the is to ds transition is marked by an increase in velocity and the flow rate and by a decrease in thickness width cross sectional area and viscosity this transition is due to an abrupt increase in the slope of the substratum the estimated velocity values are in good agreement with the measurements during the 1944 eruption the analysis used here may be extended to other lava flows some gravity flows debris mud flows floods and avalanches have rheological properties and shapes similar to those of lavas and the same process form relationships may apply to these flows the approach used here may be therefore useful for evaluating hazards from various gravity currents

geomorphological mapping with a small unmanned aircraft system suas feature detection and accuracy assessment of a photogrammetrically derived digital terrain model abstract small unmanned aircraft systems suas are a relatively new type of aerial platform for acquiring high resolution remote sensing measurements of earth surface processes and landforms however despite growing application there has been little quantitative assessment of suas performance here we present results from a field experiment designed to evaluate the accuracy of a photogrammetrically derived digital terrain model dtm developed from imagery acquired with a low cost digital camera onboard an suas we also show the utility of the high resolution 0 1 m suas imagery for resolving small scale biogeomorphic features the experiment was conducted in an area with active and stabilized aeolian landforms in the southern canadian prairies images were acquired with a hawkeye rq 84z areohawk fixed wing suas a total of 280 images were acquired along 14 flight lines covering an area of 1 95 km2 the survey was completed in 4 5 h including gps surveying suas setup and flight time standard image processing and photogrammetric techniques were used to produce a 1 m resolution dtm and a 0 1 m resolution orthorectified image mosaic the latter revealed previously un mapped bioturbation features the vertical accuracy of the dtm was evaluated with 99 real time kinematic gps points while 20 of these points were used to quantify horizontal accuracy the horizontal root mean squared error rmse of the orthoimage was 0 18 m while the vertical rmse of the dtm was 0 29 m which is equivalent to the rmse of a bare earth lidar dtm for the same site the combined error from both datasets was used to define a threshold of the minimum elevation difference that could be reliably attributed to erosion or deposition in the seven years separating the suas and lidar datasets overall our results suggest that suas acquired imagery may provide a low cost rapid and flexible alternative to airborne lidar for geomorphological mapping

improvement of surface flow network prediction for the modeling of erosion processes in agricultural landscapes themodeling of soil erosion by water supposes an accurate and thorough understanding of the hydrology thus it is critical to have a good delineation of the surface flow path the flow network data are critical for important uses such as flood forecasting and watershed management geographic information system gis functions are able to compute a flow network directly from the digital elevation models because the flow directions are only based on the topography the other factors controlling the flow directions are overlooked in the agricultural areas work such as tillage can have a large impact on the flow direction we propose a 5 step procedure to account for such man made features the use of this procedure clearly improves the quality of the computed flow network this procedure has been successfully implemented in a gis and improves the prediction of surface flow and therefore improves water erosion modeling at the watershed scale

incorporating ancillary data to refine anthropogenically modified overland flow paths a study carried out in the oldman river watershed in southern alberta canada to delineate potential surface water pollution sources revealed that the use of conventional raster based digital elevation models dems and flow direction algorithms resulted in the delineation of incorrect watershed boundaries the inaccuracies resulted from the resolution of the available dem which is too coarse to represent the presence of anthropogenically modified terrain features such as roads ditches and canals which can significantly alter overland flow paths this observation prompted the development of the computer model ridem rural infrastructure digital elevation model by incorporating ancillary data to refine anthropogenically modified overland flow paths into the grid based watershed delineation process the scale of runoff flow paths created with ridem is reduced below the scale defined by the representation of terrain with the dem ridem also resolves the inability of grid based flow direction algorithms to account for the split flow patterns that occur in irrigated landscapes the model outputs include a corrected flow direction matrix gross watershed boundaries and road induced dead drainages the watershed areas derived with ridem differed by up to 49 from watersheds derived using a conventional dem with a 20 m grid cell size however results of watershed boundaries could not be verified because highly accurate watershed boundaries do not exist for our study area copyright 2005 john wiley sons ltd

forest roads and geomorphic process interactions cascade range oregon a major flood in february 1996 triggered more than 100 geomorphic features affecting forest roads in a 181 km 2 study area in the western cascade range oregon eight types of features including mass movements and fluvial features were mapped measured and analysed using geographic information systems and sediment budgets for the road network although roads functioned as both production and depositional sites for mass movements and fluvial processes the net effect of roads was an increase in basin wide sediment production debris slides from mobilized road fills were the dominant process of sediment production from roads road related sedimentation features were concentrated in a portion of the study area that experienced a rain on snow event during the storm and was characterized by the oldest roads and steep slopes underlain by unstable highly weathered bedrock the downslope increase in frequency of features and volumes of sediment produced combined with the downslope increase in relative frequency of fluvial over mass wasting processes suggests that during an extreme storm event a road network may have major impacts on stream channels far removed from initiation sites overall this study indicated that the nature of geomorphic processes influenced by roads is strongly conditioned by road location and construction practices basin geology and storm characteristics published in 2001 by john wiley sons ltd

qualitative and quantitative applications of lidar imagery in fluvial geomorphology the potential for geomorphological mapping and quantitative calculations of light detection and ranging lidar data within fluvial geomorphology was studied for two river catchments within belgium dijle and ambleve which differ in physical settings and floodplain morphology two commercial of the shelf lidar datasets with different specifications horizontal resolution and vertical accuracy were available for parts of the floodplains of both catchments real time kinematic rtk global positioning system gps data were used as ground truth for error calculations qualitative analysis of lidar data allowed the identification of former channel patterns levees colluvial hillslope and fan deposits these results were confirmed by field data topographic surveys and historical maps the pixel resolution proved to be an important factor in the identification of small landforms only features with a width equal to or larger than lidar resolution can be detected this poses limits on the usability of regionally available lidar data which often have a horizontal resolution of several metres the lidar data were also used in a quantitative analysis of channel dynamics in the study area the width of the dijle river channel increased 3 m on average between 1969 and 2003 a sediment budget of channel processes for the period 1969 2003 indicated a total river bank erosion of 16 1 103 m3 and a total within channel deposition of 7 1 103 m3 resulting in a net river erosion of 9 0 103 m3 or c 0 4 mg year 1 per metre river length sequential lidar data can in theory be used to calculate vertical sedimentation rates as long as there is control on the error of the reference levels used copyright 2008 john wiley and sons ltd

lidar strip adjustment application to volcanic areas dems derived from lidar data are nowadays largely used for quantitative analyses and modelling in geology and geomorphology high quality dems are required for the accurate morphometric and volumetric measurement of land features we propose a rigorous automatic algorithm for correcting systematic errors in lidar data in order to assess sub metric variations in surface morphology over wide areas such as those associated with landslide slump and volcanic deposits our procedure does not require a priori knowledge of the surface such as the presence of known ground control points systematic errors are detected on the basis of distortions in the areas of overlap among different strips discrepancies between overlapping strips are assessed at a number of chosen computational tie points at each tie point a local surface is constructed for each strip containing the point displacements between different strips are then calculated at each tie point and minimization of these discrepancies allows the identification of major systematic errors these errors are identified as a function of the variables that describe the data acquisition system significant errors mainly caused by a non constant misestimation of the roll angle are highlighted and corrected comparison of dems constructed using first uncorrected and then corrected lidar data from different mt etna surveys shows a meaningful improvement in quality most of the systematic errors are removed and the accuracy of morphometric and volumetric measurements of volcanic features increases these corrections are particularly important for the following studies of mt etna calculation of lava flow volume calculation of erosion and deposition volume of pyroclastic cones mapping of areas newly covered by volcanic ash and morphological evolution of a portion of an active lava field over a short time span

the prediction of hillslope flow paths for distributed hydrological modelling using digital terrain models the accuracy of the predictions of distributed hydrological models must depend in part on the proper specification of flow pathways this paper examines some of the problems of deriving flow pathways from raster digital terrain data in the context of hydrological predictions using topmodel distributed moisture status is predicted in topmodel on the basis of spatial indices that depend on flow path definition the sensitivity of this index to flow path algorithm and grid size is examined for the case where the surface topography is a good indicator of local hydraulic gradients a strategy for the case where downslope subsurface flow pathways may deviate from those indicated by the surface topography is described with an example application

channel network extent in the context of historical land use flow generation processes and landscape evolution in the north carolina piedmont intensive agricultural land use in the 18th to early 20th centuries on the southeastern piedmont resulted in substantial soil erosion and gully development today many historically farmed areas have been abandoned and afforested and such landscapes are an opportunity to study channel network recovery from disturbance by gullying channel initiation mapping watershed area slope relationships and field monitoring of flow generation processes are used to identify channel network extent and place it in hydrologic historical and landscape evolution context in six study areas in the north carolina piedmont 100 channel heads were mapped in fully forested watersheds revealing a channel initiation relationship of 380 as1 27 where a is contributing area m2 and s is local slope m m flow in these channels is generated by subsurface and overland flow the measured relative slope exponent is lower than expected based on literature values of 2 for forested watersheds with subsurface and overland flow suggesting that the channel network extent may reflect a former hydrological regime however geomorphic evidence of recovery in channel heads within fully forested watersheds is greater than those with present day pasture present day channel heads lie within hollows or downslope of unchanneled valleys which may be remnants of historical gullies and area slope relationships provide evidence of colluvial aggradation within the valleys channel network extent appears to be sensitive to land use change with recovery beginning within decades of afforestation channel initiation mapping and area slope relationships are shown to be useful tools for interpreting geomorphic effects of land use change copyright 2012 john wiley sons ltd

detection of subtle tectonic geomorphic features in densely forested mountains by very high resolution airborne lidar survey abstract despite successes elsewhere in the world 2 m resolution dems from a standard airborne lidar survey failed to detect small tectonic geomorphic features in densely forested high relief mountains of central japan our new 0 5 m dems from an unprecedentedly high resolution lidar survey along the neodani fault now reveal a number of previously unknown fault scarps as well as other hidden geomorphic features the survey achieves a ground return density of 6 2 m 2 out of a total shot density of as much as 12 7 m 2 the main factor to gain sufficient ground returns in unfavorable conditions is a large side lap of 70 between flight swaths which means that any specific area in the target zone is scanned three or more times from different angles evaluation of dems with resolution from 0 25 to 10 m assures that a 0 5m resolution lidar dem is necessary for the detection of subtle tectonic breaks another key factor for complete detection of small tectonic geomorphic features is the application of a recently developed dem visualization red relief image map rrim which allows mapping of all the small features with various sizes orientations and morphology overcoming major drawbacks of classic dem visualizations a very high resolution lidar survey aided with rrim visualization as used in this study provides a more reliable approach for the detailed mapping of slight active fault traces hidden under dense vegetation

analysis of lidar derived topographic information for characterizing and differentiating landslide morphology and activity abstract this study used airborne laser altimetry lidar to examine the surface morphology of two canyon rim landslides in southern idaho the high resolution topographic data were used to calculate surface roughness slope semivariance and fractal dimension these data were combined with historical movement data global positioning systems gps and laser theodolite and field observations for the currently active landslide and the results suggest that topographic elements are related to the material types and the type of local motion of the landslide weak unconsolidated materials comprising the toe of the slide which were heavily fractured and locally thrust upward had relatively high surface roughness high fractal dimension and high vertical and lateral movement the body of the slide which predominantly moved laterally and consists mainly of undisturbed older canyon floor materials had relatively lower surface roughness than the toe the upper block consisting of a down dropped section of the canyon rim that has remained largely intact had a low surface roughness on its upper surface and high surface roughness along fractures and on its west face unrelated to landslide motion the upper block also had a higher semivariance than the toe and body the topographic data for a neighboring older and larger landslide complex which failed in 1937 are similarly used to understand surface morphology as well as to compare to the morphology of the active landslide and to understand scale dependent processes the morphometric analyses demonstrate that the active landslide has a similar failure mechanism and is topographically more variable than the 1937 landslide especially at scales 20 m weathering and the larger scale processes of the 1937 slide are hypothesized to cause the lower semivariance values of the 1937 slide at smaller scales

modeling the topography of shallow braided rivers using structure from motion photogrammetry abstract recent advances in computer vision and image analysis have led to the development of a novel fully automated photogrammetric method to generate dense 3d point cloud data this approach termed structure from motion or sfm requires only limited ground control and is ideally suited to imagery obtained from low cost non metric cameras acquired either at close range or using aerial platforms terrain models generated using sfm have begun to emerge recently and with a growing spectrum of software now available there is an urgent need to provide a robust quality assessment of the data products generated using standard field and computational workflows to address this demand we present a detailed error analysis of sub meter resolution terrain models of two contiguous reaches 1 6 and 1 7 km long of the braided ahuriri river new zealand generated using sfm a six stage methodology is described involving i hand held image acquisition from an aerial platform ii 3d point cloud extraction modeling using agisoft photoscan iii georeferencing on a redundant network of gps surveyed ground control points iv point cloud filtering to reduce computational demand as well as reduce vegetation noise v optical bathymetric modeling of inundated areas and vi data fusion and surface modeling to generate sub meter raster terrain models bootstrapped geo registration as well as extensive distributed gps and sonar based bathymetric check data were used to quantify the quality of the models generated after each processing step the results obtained provide the first quantified analysis of sfm applied to model the complex terrain of a braided river results indicate that geo registration errors of 0 04 m planar and 0 10 m elevation and vertical surface errors of 0 10 m in non vegetation areas can be achieved from a dataset of photographs taken at 600 m and 800 m above the ground level these encouraging results suggest that this low cost logistically simple method can deliver high quality terrain datasets competitive with those obtained with significantly more expensive laser scanning and suitable for geomorphic change detection and hydrodynamic modeling