LiDAR DEM Research Articles

An Investigation of DEM Resolution Influence on Flood Inundation Simulation

This study investigates the influence of DEM resolutions on flood inundation simulation. Sanyei drainage area of Tainan City is taken as a case study. The catchment of Sanyei area is 43.7 km2 with a main stream of 6.7km and elevations running from 2 m to 30 m. This study uses 1x1 m LiDAR DEM of Sanyei area as a basis. To do pure 2D flood simulation, the channel elevation is adjusted based on the cross-sectional measurements. The channel adjusted 1x1m DEM is later used as basis to aggregate several DEMs including: 5x5m, 10x10m, 20x20m, 40x40m. Five flood inundation models were built based on the 5 DEMs mentioned above with a same model setting. Results show that the inundation area evaluation increases with coarser DEMs. Specifically, the inundation area given by the 40x40m DEM is 1.5 times greater than that given by the 1x1m DEM. This may not only lead to different decision making in evacuation route and responses, but also the evaluation of economic loss and project planning, etc.

Using high resolution LIDAR DEM to reconstruct historical network of lakes and wetlands in the Northern part of the Moldavian Plateau, NE Romania

A particular environmental feature of the northern part of Moldavian Plateau (NE Romania) is the large number of anthropic lakes along river courses. Even more, due to climatic, hydrological, hydrogeological and geomorphological settings and human activities (dominated by an extensive agriculture) this characteristic was mentioned and mapped in writen records and cartographic representations in many historical stages of the humanization of this region. The need for watter supply have forced the inhabitants to build dams of various sizes along the entire river network. Over the time, many dams were abandoned, while others have been relocated with a impresive dynamic at historical time scale

Using airborne EM and borehole NMR data to map the transmissivity of a shallow semi-confined aquifer, western NSW

SUMMARY The Broken Hill Managed Aquifer Recharge (BHMAR) project aimed to define key groundwater resources and aquifer storage options in the lower Darling River floodplain of western NSW. The project was multidisciplinary and utilised airborne electromagnetics (AEM), borehole nuclear magnetic resonance (NMR) and LiDAR DEM data and lithological, hydrostratigraphic and hydrochemical information to develop a suite of hydrogeological and groundwater property maps and products. This abstract discusses the methods and results of estimating the transmissivity of the semi-confined target aquifer. Hydrostratigraphy and hydraulic texture classes were mapped by interpreting the AEM data in conjunction with borehole geophysics and lithological information. Aquifer transmissivity was statistically derived by combining borehole NMR hydraulic conductivity estimates with the mapped 3D distribution of texture classes and hydrostratigraphic units. Using a statistical and GIS approach, the derived aquifer thicknesses in the key areas ranged from 20 - 40 m and the lower and upper transmissivity bounds ranged from 1 to 10 m 2 /d, and 10 m 2 /d to 1000 m 2 /d, respectively.

Integration of LiDAR and cropmark remote sensing for the study of fluvial and anthropogenic landforms in the Brenta–Bacchiglione alluvial plain (NE Italy)

The geomorphological study of alluvial plains takes great advantage from the integration of detailed altimetry with high-resolution images, especially in the lower-relief sectors, like those in the distal plain of the Brenta and Bacchiglione rivers near the city of Padua (mean slope 1–0.8‰). The LiDAR data which were specifically acquired for this research (Riegl LMS-Q560, mean density 7points/m2, overall area 123km2), were classified and interpolated in order to map fluvial and anthropogenic landforms. The acquisition was carried out in a moment of minimal vegetation luxuriance (March 2011), in order to minimize ground cover. The DEM (z accuracy <5–10cm) was processed and analyzed in integration with high resolution oblique and vertical, multispectral (VIS+IR) and panchromatic aerial images. These latter were acquired during the summer crop season, with the aim of maximizing the detection of vegetation response to different soils, sediments and landforms (cropmarks). A detailed field survey was conducted with soil observation, hand augerings and description of stratigraphic sections in pits, in order to validate the remote sensing interpretations. The detailed topography allowed the identification and mapping of low rise interfluves and scarps (<1–2m), paleochannels, scroll bars and crevasse splays. The reconstruction of a precise “ground” surface in the narrow medieval streets detailed the morphology of the multi-stratified archeological mound in the historical center of Padua. The remote sensing of cropmarks is the most appropriate method to complete the mapping of the numerous fluvial forms that have little or no topographic expression being too small (i.e. minor crevasse channels and splays) and/or flattened by anthropogenic activity (mainly plowing). LiDAR intensity permitted a precise mapping of LGM deposits that have shown peculiar reflectivity related to specific soil characteristics (i.e., presence of calcic horizons in well-drained, elevated position). High resolution images and LiDAR DEM allow the analysis of this largely anthropized low-plain environment at cell-size scale of 0.5–1m, i.e. approximating the original complexity of the alluvial sedimentary environment. The results bring advances in the comprehension of the Last Glacial Maximum and Holocene evolution of the Brenta-Bacchiglione plain. The large-scale mapping of paleohydrographic features led to the recognition of different fluvial styles adopted by the Brenta River: i) braided to wandering paleochannels, 100–300m wide, in fine-sediment dominated fluvioglacial LGM distal alluvial plain, ii) meandering (up to ~3.5) single channels, 50–100m wide, with evidence of lateral migration in early and middle Holocene channel belts, and iii) low to medium sinuosity (~1.15–1.5) single channels with vertical aggradation, associated with ridges and widespread crevasse channels and splays during the middle Holocene. The derived maps provide significant support to land and urban planning, e.g., in the definition of appropriate geotechnical analysis, the estimation of buried archeological deposits in the city center, and the assessment of flooding hazard.

Large Scale Landform Mapping Using Lidar DEM

In this study, LIDAR DEM data was used to obtain a primary landform map in accordance with a well-known methodology. This primary landform map was generalized using the Focal Statistics tool (Majority), considering the minimum area condition in cartographic generalization in order to obtain landform maps at 1:1000 and 1:5000 scales. Both the primary and the generalized landform maps were verified visually with hillshaded DEM and an orthophoto. As a result, these maps provide satisfactory visuals of the landforms. In order to show the effect of generalization, the area of each landform in both the primary and the generalized maps was computed. Consequently, landform maps at large scales could be obtained with the proposed methodology, including generalization using LIDAR DEM.

Comparative analysis of the differences between using LiDAR and contour-based DEMs for hydrological modeling of runoff generating debris flows in the Dolomites

Citation: Degetto M, Gregoretti C and Bernard M (2015) Comparative analysis of the differences between using LiDAR and contour-based DEMs for hydrological modeling of runoff generating debris flows in the Dolomites. Front. Earth Sci. 3:21. doi: 10.3389/feart.2015.00021 Comparative analysis of the differences between using LiDAR and contour-based DEMs for hydrological modeling of runoff generating debris flows in the Dolomites

Co-seismic vertical displacements from a single post-seismic lidar DEM: example from the 2010 El Mayor-Cucapah earthquake

Co-seismic vertical displacements from a single post-seismic lidar DEM: example from the 2010 El Mayor-Cucapah earthquake

Rapid Inundation Modelling in Large Floodplains Using LiDAR DEM

Rapid and accurate inundation modelling in large floodplains is critical for emergency response and environmental management. This paper describes the development and implementation of a floodplain inundation model that can be used for rapid assessment of inundation in very large floodplains. The model uses high resolution DEM (such as LiDAR DEM) to derive floodplain storages and connectivity between them at different river stages. We tested the performance of the model across several large floodplains in southeast Australia for estimating floodplain inundation extent, volume, and water depth for a few recent flood events. The results are in good agreement with those obtained from high resolution satellite imageries and MIKE 21 two-dimensional hydrodynamic model. The model performed particularly well in the reaches that have confined channels with above 85 % agreement with the flood maps derived from Landsat TM imagery in cell-to-cell comparison. While the model did not performance as well in the flat and complex floodplains, the overall level of agreement of the modelled inundation maps with the satellite flood maps was still satisfactory (60–75 %). The key advantage of this model is demonstrated by its capability to simulate inundation in large floodplains (over 2000 km2) at a very high resolution of 5-m with more than 81 million cells at a reasonably low computational cost. The model is suitable for practical floodplain inundation simulation and scenario modelling under current and future climate conditions.

Flood mapping using LIDAR DEM. Limitations of the 1-D modeling highlighted by the 2-D approach

Nowadays, the use of 2-D fully dynamic models represents the most reliable approach for flood inundation and flood hazard studies, especially in complex applications. However, 1-D modeling is still a widely used approach due to the reduced computational time and cost. The introduction of LIDAR technique has stimulated a more detailed topographic description of river reaches. As a result, this huge amount of topographic data can lead to significant improvements in the 1-D computations. Therefore, the main purpose of this paper is to realize how the improvements in the topographic description can reduce the difference between 1-D and 2-D models, highlighting at the same time the critical aspects and the limitations of 1-D approach in the hydraulic simulation as well as in the spatial representation of the results. The analysis presented in the paper refers to two actual case studies for which terrestrial and airborne LIDAR DEMs were collected on purpose. The results of those applications show that the use of 1-D models requires a greater hydraulic skilfulness than the use of 2-D model.

LiDAR Elevation and DEM Errors in Forested Settings

igital elevation models (DEMs) form the basis of LiDAR derived tree height measurements and other topographic modeling needs within natural resource applications. We compared 2873 digital total station elevations to the closest discrete LiDAR elevation point and DEM raster cell across several forest and topographic settings. We also examined limiting comparisons to points within 0.5 m and within one meter. Using all nearest LiDAR points, average total station plot elevation differences ranged from -0.06 m (SD 0.40) to -0.59 m (SD 0.23) indicating that LiDAR elevations are higher than actual elevations. LiDAR DEM differences ranged from -0.09 (SD 0.41) to -0.56 m (SD 0.70). We also compared mapping-grade GPS receiver measurements to LiDAR point elevation and DEMs. Average plot GPS elevation differences ranged from 0.24 (SD 1.55) to 2.82 m (SD 4.58) for the nearest LiDAR point, and from 0.27 (SD 2.33) to 2.69 m (SD 5.06) for LiDAR DEMs. We believe that our efforts represent one of the most robust studies of LiDAR measurement errors available in published literature. The relatively small measurement differences that we found between LiDAR elevations and our most reliable field-based method of elevations, the digital total station, demonstrate the potential for LiDAR in forestry and natural resource applications.

Analiza rzeźby stoliwa Szczelińca Wielkiego w Górach Stołowych na podstawie numerycznego modelu terenu z danych LiDAR

Analiza rzeźby stoliwa Szczelińca Wielkiego w Górach Stołowych na podstawie numerycznego modelu terenu z danych LiDAR

Testing different cross-section spacing in 1D hydraulic modelling: a case study on Johor River, Malaysia

Cross-section data are essential to describe the topography of rivers and floodplain areas and support flood propagation and inundation modelling. To date, there are only a few guidelines available to assist hydraulic modellers in determining the required quantity and location of cross-sections. The aim of this paper is to investigate the impact of cross-section spacing on the results of hydraulic models. To this end, four hydraulic models were built using the HEC-RAS model code and four different numbers of cross-sections. The geometric data were extracted from a high-resolution digital elevation model (LiDAR DEM) of a 30-km reach of the Johor River in Malaysia. These hydraulic models were then compared using flood water levels recorded at two stream gauging stations during two recent flood events. The independent calibration and validation of the models allowed the evaluation of a set of equations proposed in the literature for determining the distance between cross-sections for hydraulic modelling.Editor D. Koutsoyiannis; Associate editor I. Nalbantis

Geological and geomorphological features of deep-seated catastrophic landslides in tectonically active regions of Asia and implications for hazard mapping

Deep-seated catastrophic landslides, particularly rock or debris avalanches, travel extremely rapidly for long distances, causing severe damage over wide areas. This paper summarizes the geological and geomorphological features of such events, which were induced by earthquakes and rainstorms in Asia, and then uses these features to predict future potential sites of failures. Most of the rock avalanches are preceded by gravitational slope deformation with topographic features, in which small scarps along future head of landslide are the most representative; the scarps can be identified in topographic images made by high-resolution airborne LiDAR DEMs and may suggest the instability just before catastrophic failure. Earthquake-induced debris avalanches of pyroclastic fall deposits are not preceded by gravitational slope deformation but are of specific type and sequence of deposits, in which resilicified paleosol with halloysite may be the most important to accommodate a sliding surface.

Inaccuracy introduced by LiDAR-generated cross sections and its impact on 1D hydrodynamic simulations

High-quality topographic data is an essential prerequisite for any hydrologic simulation. In recent years, LiDAR measurements have been used as a reliable method for obtaining such data even though it has its own flaws. This article focuses on analysis of error introduced by LiDAR-based elevation scanning due to the fact that the near-IR laser beam (1,064 nm) cannot penetrate water masses. Such error may affect derived structures (cross sections) and it influences hydrodynamic simulations as well. Motivation for our research was mainly the insufficient amount of measured cross sections on tributary channels in our study area (Moravian-Silesian Region) and evaluation/correction of error dragged into hydrodynamic modeling when LiDAR-based cross sections are used instead. In our article, we compared two data sets of cross sections: real cross sections created from direct measurements of the river channel and cross sections of the same river channel extracted from LiDAR (9 cross sections, 0.2 m LiDAR DEM resolution, gauge stations and floodplains data were used). As it was expected, the inaccuracies between these two cross-section data sets radically affected the results of the HEC-RAS simulation in the study area (the confluence of rivers Olse and Stonavka). Some known methods for depth estimation and flow area estimation were used for correction of these errors and as a conclusion of the study a recommendation is presented: inaccuracies introduces by LiDAR’s inability to penetrate water masses must be taken into account and must be corrected according to the catchment-specific conditions. We also showed that double-linear depth estimation method works well when dealing with low-flow conditions in upland catchment study area.

Influence of topography and basement depth on surface rupture morphology revealed from LiDAR and field mapping, Hope Fault, New Zealand

High-resolution airborne LiDAR and field mapping were used to investigate a 29km-long section of the Hurunui segment of the Hope Fault concealed beneath beech forest. Approximately 20km of the dextral strike-slip principal slip zone (PSZ) was identified as a series of 69 individual fault strands on the LiDAR DEM. Mapping revealed 70 normal, 55 dextral-reverse, and 100 secondary faults, many of which were previously unrecognized. Secondary faults are kinematically linked with the PSZ and comprise a complex surface fault deformation zone (FDZ). A Rose diagram weighted by the lengths of the PSZ strands shows that the Hurunui segment strikes between 070° and 075° and is optimally oriented for dextral strike-slip within the regional stress field. The observed fault zone complexity is thus unlikely to result from large-scale fault mis-orientation with respect to regional stresses. FDZ width measurements from 415 locations reveal a spatially-variable, active FDZ up to ~500m wide with an average width of 200m. FDZ width increases with increased hanging wall topography and increased topographic relief (e.g., adjacent to high topography with deeply incised streams), suggesting that along-strike topographic perturbations to fault geometry and stress states increase fault zone complexity and width. Where adjacent PSZ strands strike between 070° and 075°, the FDZ is ≤150m wide, however, FDZ width increases where the tips of adjacent PSZ segments locally vary in strike by ≥10°. FDZ width and surface fracture density also appear to increase with increasing thickness of alluvial deposits overlying bedrock. Our results indicate that spatial variations in near-fault topography and geology can generate along-strike variability in the morphology of surface ruptures, even in the case of fast-slipping, structurally mature faults where more confined, simplistic ruptures are expected at seismogenic depths.

Extraction and application analysis of landslide influential factors based on LiDAR DEM: a case study in the Three Gorges area, China

The aim of this study was to identify some new factors that may impact the occurrence and distribution of landslides based on light detection and ranging digital elevation model (LiDAR DEM), and to examine whether these factors can apply to distinguish between landslide and non-landslide pixels. Twenty-one landslide influential factors were identified. Thereinto, there were ten novel factors, namely the texture factors of slope and surface roughness, including the contrast (Con), correlation (Cor), angular second moment, entropy, and homogeneity (Hom) textures. Qualitative and quantitative analysis and feature selection method were applied to examine the application of these factors. The analysis results indicate that these factors have certain abilities to distinguish between landslide and non-landslide objects. And the selected optimal factors combination that derived from feature selection method was DEM, slope, Hom_d, Con_s, Cor_s, Hom_s, Con_r, Cor_r, and Hom_r (_d, _s, and _r represent DEM, slope, and surface roughness textures, respectively). In conclusion, the identified landslide influential factors can provide effective information for landslide identification. And the new texture factors of slope and surface roughness could act as important measurements that can improve the precision of landslide inventory mapping, susceptibility mapping, and risk assessment.

Tephrochronology and distribution characteristics using LiDAR DEMs of the Nasu volcanic debris avalanche deposits

Tephrochronology and distribution characteristics using LiDAR DEMs of the Nasu volcanic debris avalanche deposits

Sensitivity of watershed attributes to spatial resolution and interpolation method of LiDAR DEMs in three distinct landscapes

AbstractThis study investigates scaling relationships of watershed area and stream networks delineated from LiDAR DEMs. The delineations are tested against spatial resolution, including 1, 5, 10, 25, and 50 m, and interpolation method, including Inverse Distance Weighting (IDW), Moving Average (MA), Universal Kriging (UK), Natural Neighbor (NN), and Triangular Irregular Networks (TIN). Study sites include Mosquito Creek, Scotty Creek, and Thomas Brook, representing landscapes with high, low, and moderate change in elevation, respectively. Results show scale‐dependent irregularities in watershed area due to spatial resolution at Thomas Brook and Mosquito Creek. The highest sensitivity of watershed area to spatial resolution occurred at Scotty Creek, due to high incidence of LiDAR sensor measurement error and subtle changes in elevation. Length of drainage networks did not show a scaling relationship with spatial resolution, due to algorithmic complications of the stream initiation threshold. Stream lengths of main channels at Thomas Brook and Mosquito Creek displayed systematic increases in length with increasing spatial resolution, described through an average fractal dimension of 1.059. The scaling relationship between stream length and DEM resolution allows estimation of stream lengths from low‐resolution DEMs in the absence of high‐resolution DEMs. Single stream validation at Thomas Brook showed the 1 m DEM produced the lowest length error and highest spatial accuracy, at 3.7% and 71.3%, respectively. Single stream validation at Mosquito Creek showed the 25 m DEM produced the lowest length error, and the 1 m DEM the highest spatial accuracy, at 0.6% and 61.0%, respectively.

Spatial probabilistic approach on landslide susceptibility assessment from high resolution sensors derived parameters

Landslide occurrence depends on various interrelating factors which consequently initiate to massive mass of soil and rock debris that move downhill due to the gravity action. LiDAR has come with a progressive approach in mitigating landslide by permitting the formation of more accurate DEM compared to other active space borne and airborne remote sensing techniques. The objective of this research is to assess the susceptibility of landslide in Ulu Klang area by investigating the correlation between past landslide events with geo environmental factors. A high resolution LiDAR DEM was constructed to produce topographic attributes such as slope, curvature and aspect. These data were utilized to derive second deliverables of landslide parameters such as topographic wetness index (TWI), surface area ratio (SAR) and stream power index (SPI) as well as NDVI generated from IKONOS imagery. Subsequently, a probabilistic based frequency ratio model was applied to establish the spatial relationship between the landslide locations and each landslide related factor. Factor ratings were summed up to obtain Landslide Susceptibility Index (LSI) to construct the landslide susceptibility map.

Late Cenozoic Tectonic Activity of the Śnieżnik Massif Area (Sudetes, Sw Poland)in the Light of Lidar Dem Morphometric Analysis

AbstractŚnieżnik Massif represents a prominent morphological feature in the East Sudetes, which is bounded by a system of faults controlling its differential uplift. Vertical movements originated at least during the Oligocene times, with culmination phase in Pliocene times, whereas estimated total uplift was in the range of 500-1000 meters. This study presents a qualitative (geomorphometric) and quantitative (morphotectonic) approach that combines Late Cenozoic tectonic uplift model with landscape evolution theories. Application of basin asymmetry factor (AF) and hypsometric integral (Hi) analyses allowed recognizing a NW trending tilted fault blocks. They originated as a result of Palaeogene planation surface braking and differential uplift. Uplift and later fault-block tilting in the Śnieżnik Massif morphotectonic unit, were generally realized along NE-SW striking Wilkanow fault to the west and WNW-ESE striking southern fault zone, as expressed here e.g. by Potoczek-Branna, Herˇmranice and Pisary faults.