scholarly journals Application of Geological Mapping Using Airborne-Based LiDAR DEM to Tunnel Engineering: Example of Dongao Tunnel in Northeastern Taiwan

2021 ◽  
Vol 11 (10) ◽  
pp. 4404
Author(s):  
Pai-Chiao Lo ◽  
Wei Lo ◽  
Tai-Tien Wang ◽  
Yu-Chung Hsieh
Keyword(s):  
Large Scale ◽  
Value Added ◽  
Geological Mapping ◽  
Tunnel Engineering ◽  
Geological Investigation ◽  
Geological Surveys ◽  
Highway Tunnel ◽  
Digital Elevation ◽  
Geomorphic Features ◽  
Lidar Dem

The use of digital elevation models (DEMs) that use airborne-based light detection and the ranging technique (airborne-based LiDAR) to understand large-scale geological structures has become important in geological surveying and mapping. Taking the Dongao Tunnel area in northeastern Taiwan as the study area, this study used the airborne-based LiDAR DEM and related value-added maps to interpret the topographic and geomorphic features of the area and identify locations for geological investigation. The characteristics of the rock mass were observed on-site and revealed by excavation of the highway tunnel in the study area; they were compared with the interpreted topographic and geomorphic features to determine the potential of using 1 m-resolution LiDAR DEM in geological surveys and in the evaluation of engineering characteristics of underground rock masses. The results of this study demonstrated that the DEM accurately captured geomorphic features: the strata composed of slate and schist had distinct appearances in both the clinometric map and the hillshade map; the locations of faults, lineaments, and drainage were consistent with those observed on-site, and the positions of these features were captured more accurately than those on conventional maps. Evident microrelief features, including the distribution of scarps, erosion gullies, and mini-drainage systems provide an effective basis for interpreting a deep-seated gravitational deformation slope and for an on-site inspection for validation. The use of high-resolution LiDAR DEM to interpret geomorphic features along with geological surveys provides a more comprehensive understanding of the survey area, supporting surveys and geological mapping, revealing the locations of potential slope failures, and enabling the assessment of tunnel engineering risks.

scholarly journals Quality assessment of DEM derived from topographic maps for geomorphometric purposes

2019 ◽  
Vol 11 (1) ◽  
pp. 843-865 ◽  
Author(s):  
Bartłomiej Szypuła
Keyword(s):  
Laser Scanning ◽  
Large Scale ◽  
Reference Model ◽  
Quality Parameters ◽  
Topographic Maps ◽  
Topographic Map ◽  
Digital Elevation ◽  
Gps Rtk ◽  
Lidar Dem ◽  
Fine Resolution

Abstract Digital elevation models (DEMs) play a significant role in geomorphological research. For geomorphologists reconstructing landform and drainage structure is frequently as important as elevation accuracy. Consequently, large-scale topographic maps (with contours, height points and watercourses) constitute excellent material for creating models (here called Topo-DEM) in fine resolution. The purpose of the conducted analyses was to assess the quality of Topo-DEM against freely-available global DEMs and then to compare it with a reference model derived from laser scanning (LiDAR-DEM). The analysis also involved derivative maps of geomorphometric parameters (local relief, slope, curvature, aspect) generated on the basis of Topo-DEM and LiDAR-DEM. Moreover, comparative classification of landforms was carried out. It was indicated that Topo-DEM is characterised by good elevation accuracy (RMSE <2 m) and reflects the topography of the analyzed area surprisingly well. Additionally, statistical and percentage metrics confirm that it is possible to generate a DEM with very good quality parameters on the basis of a large-scale topographic map (1:10,000): elevation differences between Topo-DEM and: 1) topographic map amounted from−1.68 to +2.06 m,MAEis 0.10 m, RMSE 0.16 m; 2) LiDAR-DEM (MAE 1.13 m, RMSE 1.69 m, SD 1.83 m); 3) GPS RTK measurements amounted from−3.6 to +3.01 m, MAE is 0.72 m, RMSE 0.97 m, SD 0.97 m. For an area of several dozen km2 Topo-DEM with 10×10 m resolution proved more efficient than detailed (1×1 m) LiDAR-DEM.

scholarly journals Multi-Country Scale Assessment of Available Energy Recovery Potential Using Micro-Hydropower in Drinking, Pressurised Irrigation and Wastewater Networks, Covering Part of the EU

Water ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 899
Author(s):  
Djordje Mitrovic ◽  
Miguel Crespo Chacón ◽  
Aida Mérida García ◽  
Jorge García Morillo ◽  
Juan Antonio Rodríguez Diaz ◽  
...  
Keyword(s):  
Drinking Water ◽  
Northern Ireland ◽  
Energy Recovery ◽  
Large Scale ◽  
Significant Proportion ◽  
Value Added ◽  
Cost Effective ◽  
Net Energy ◽  
Water Networks ◽  
Scale Assessment

Studies have shown micro-hydropower (MHP) opportunities for energy recovery and CO2 reductions in the water sector. This paper conducts a large-scale assessment of this potential using a dataset amassed across six EU countries (Ireland, Northern Ireland, Scotland, Wales, Spain, and Portugal) for the drinking water, irrigation, and wastewater sectors. Extrapolating the collected data, the total annual MHP potential was estimated between 482.3 and 821.6 GWh, depending on the assumptions, divided among Ireland (15.5–32.2 GWh), Scotland (17.8–139.7 GWh), Northern Ireland (5.9–8.2 GWh), Wales (10.2–8.1 GWh), Spain (375.3–539.9 GWh), and Portugal (57.6–93.5 GWh) and distributed across the drinking water (43–67%), irrigation (51–30%), and wastewater (6–3%) sectors. The findings demonstrated reductions in energy consumption in water networks between 1.7 and 13.0%. Forty-five percent of the energy estimated from the analysed sites was associated with just 3% of their number, having a power output capacity >15 kW. This demonstrated that a significant proportion of energy could be exploited at a small number of sites, with a valuable contribution to net energy efficiency gains and CO2 emission reductions. This also demonstrates cost-effective, value-added, multi-country benefits to policy makers, establishing the case to incentivise MHP in water networks to help achieve the desired CO2 emissions reductions targets.

scholarly journals Using Sentinel-2 Images to Estimate Topography, Tidal-Stage Lags and Exposure Periods over Large Intertidal Areas

2021 ◽  
Vol 13 (2) ◽  
pp. 320
Author(s):  
José P. Granadeiro ◽  
João Belo ◽  
Mohamed Henriques ◽  
João Catalão ◽  
Teresa Catry
Keyword(s):  
Large Scale ◽  
Exposure Period ◽  
Intertidal Area ◽  
Digital Elevation ◽  
Geographical Bias ◽  
Novel Method ◽  
Tidal Stage ◽  
Sentinel 2

Intertidal areas provide key ecosystem services but are declining worldwide. Digital elevation models (DEMs) are important tools to monitor the evolution of such areas. In this study, we aim at (i) estimating the intertidal topography based on an established pixel-wise algorithm, from Sentinel-2 MultiSpectral Instrument scenes, (ii) implementing a set of procedures to improve the quality of such estimation, and (iii) estimating the exposure period of the intertidal area of the Bijagós Archipelago, Guinea-Bissau. We first propose a four-parameter logistic regression to estimate intertidal topography. Afterwards, we develop a novel method to estimate tide-stage lags in the area covered by a Sentinel-2 scene to correct for geographical bias in topographic estimation resulting from differences in water height within each image. Our method searches for the minimum differences in height estimates obtained from rising and ebbing tides separately, enabling the estimation of cotidal lines. Tidal-stage differences estimated closely matched those published by official authorities. We re-estimated pixel heights from which we produced a model of intertidal exposure period. We obtained a high correlation between predicted and in-situ measurements of exposure period. We highlight the importance of remote sensing to deliver large-scale intertidal DEM and tide-stage data, with relevance for coastal safety, ecology and biodiversity conservation.

scholarly journals ON GENERATING DIGITAL ELEVATION MODELS FROM LIDAR DATA – RESOLUTION VERSUS ACCURACY AND TOPOGRAPHIC WETNESS INDEX INDICES IN NORTHERN PEATLANDS

2012 ◽  
Vol 38 (2) ◽  
pp. 57-69 ◽  
Author(s):  
Abdulghani Hasan ◽  
Petter Pilesjö ◽  
Andreas Persson
Keyword(s):  
Large Scale ◽  
Drainage Area ◽  
Data Sets ◽  
Topographic Wetness Index ◽  
Absolute Deviation ◽  
Digital Elevation ◽  
Elevation Data ◽  
Scale Modelling ◽  
Data Points ◽  
Emission Modelling

Global change and GHG emission modelling are dependent on accurate wetness estimations for predictions of e.g. methane emissions. This study aims to quantify how the slope, drainage area and the TWI vary with the resolution of DEMs for a flat peatland area. Six DEMs with spatial resolutions from 0.5 to 90 m were interpolated with four different search radiuses. The relationship between accuracy of the DEM and the slope was tested. The LiDAR elevation data was divided into two data sets. The number of data points facilitated an evaluation dataset with data points not more than 10 mm away from the cell centre points in the interpolation dataset. The DEM was evaluated using a quantile-quantile test and the normalized median absolute deviation. It showed independence of the resolution when using the same search radius. The accuracy of the estimated elevation for different slopes was tested using the 0.5 meter DEM and it showed a higher deviation from evaluation data for steep areas. The slope estimations between resolutions showed differences with values that exceeded 50%. Drainage areas were tested for three resolutions, with coinciding evaluation points. The model ability to generate drainage area at each resolution was tested by pair wise comparison of three data subsets and showed differences of more than 50% in 25% of the evaluated points. The results show that consideration of DEM resolution is a necessity for the use of slope, drainage area and TWI data in large scale modelling.

Mechanics Research on Rock Stress and Deformation of Lancang River Canyon's Large - Scale Dumping Deformation

2013 ◽  
Vol 353-356 ◽  
pp. 318-323
Author(s):  
Song Ye ◽  
Yu Sheng Li ◽  
Qian Guo
Keyword(s):  
Large Scale ◽  
Geological Structure ◽  
Deformation Characteristics ◽  
Deep Part ◽  
Trailing Edge ◽  
Geological Surveys ◽  
Depth Analysis ◽  
Numerical Simulation Methods ◽  
Complex Geological Structure ◽  
Stress And Deformation

This article is based on geological surveys combined with finite element and discrete element numerical simulation methods. In-depth analysis of the complex geological structure, deformation characteristics and stress - deformation problems of dumping rock, we clarify different deformation characteristics of deformable landslide inside, at the bottom and the deep part of trailing edge, and demonstrate the deformation will gradually shift from dumping to shear slip. Potential deformation failure mode will be dumped into the whole sliding - tension, which is controlled by the bottom broken belt, and potential deformation is mainly subject to the bottom fault F207-3 of deformed rock and the dumping broken belt at the deep part of trailing edge.

Correspondence between Site Amplification and Topographical, Geological Parameters: Collation of Data from Swiss and Japanese Stations, and Neural Networks-Based Prediction of Local Response

2021 ◽  
Author(s):  
Paolo Bergamo ◽  
Conny Hammer ◽  
Donat Fäh
Keyword(s):  
Frequency Response ◽  
Large Scale ◽  
Site Response ◽  
Low Frequency ◽  
Field Measurements ◽  
Site Amplification ◽  
Local Response ◽  
Regional Variability ◽  
Individual Site ◽  
Digital Elevation

ABSTRACT We address the relation between seismic local amplification and topographical and geological indicators describing the site morphology. We focus on parameters that can be derived from layers of diffuse information (e.g., digital elevation models, geological maps) and do not require in situ surveys; we term these parameters as “indirect” proxies, as opposed to “direct” indicators (e.g., f0, VS30) derived from field measurements. We first compiled an extensive database of indirect parameters covering 142 and 637 instrumented sites in Switzerland and Japan, respectively; we collected topographical indicators at various spatial extents and focused on shared features in the geological descriptions of the two countries. We paired this proxy database with a companion dataset of site amplification factors at 10 frequencies within 0.5–20 Hz, empirically measured at the same Swiss and Japanese stations. We then assessed the robustness of the correlation between individual site-condition indicators and local response by means of statistical analyses; we also compared the proxy-site amplification relations at Swiss versus Japanese sites. Finally, we tested the prediction of site amplification by feeding ensembles of indirect parameters to a neural network (NN) structure. The main results are: (1) indirect indicators show higher correlation with site amplification in the low-frequency range (0.5–3.33 Hz); (2) topographical parameters primarily relate to local response not because of topographical amplification effects but because topographical features correspond to the properties of the subsurface, hence to stratigraphic amplification; (3) large-scale topographical indicators relate to low-frequency response, smaller-scale to higher-frequency response; (4) site amplification versus indirect proxy relations show a more marked regional variability when compared with direct indicators; and (5) the NN-based prediction of site response is the best achieved in the 1.67–5 Hz band, with both geological and topographical proxies provided as input; topographical indicators alone perform better than geological parameters.

scholarly journals Analysis of Detection and Treatment Schemes of Highway Tunnel Lining Cracks

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Yike Wei ◽  
Lingfeng Yu
Keyword(s):  
Daily Life ◽  
Tunnel Lining ◽  
Detection Methods ◽  
Tunnel Engineering ◽  
Highway Tunnel ◽  
People’S Daily ◽  
People's Daily

Highway tunnels play a very important role in people's daily life. Among them, lining is an essential part of tunnel engineering, and the quality of lining greatly affects the overall quality of the tunnel. On this basis, the causes of lining cracks and the detection methods of existing highway tunnel lining cracks are analyzed, and the treatment countermeasures for highway tunnel lining cracks are proposed.

scholarly journals Discussion on Landscape and Greening Technology of Highway Structural Tunnel Entrance

2021 ◽  
Vol 261 ◽  
pp. 03035
Author(s):  
Liu Ming ◽  
Liu Zhiqiang ◽  
Qiang Rongrong
Keyword(s):  
Cultural Landscape ◽  
Practical Stability ◽  
Tunnel Engineering ◽  
Portal Area ◽  
Highway Tunnel ◽  
Exposed Part ◽  
Tunnel Portal ◽  
Tunnel Entrance

Highway tunnel entrance is not only the exposed part of mountain in the tunnel engineering, but also an integral part of the highway breaking through the mountain. On the premise of ensuring the safety of tunnel entrance, it is important to realize the unity of safety and practical “stability” and landscape greening “beauty” of the expressway tunnel through reasonable aesthetic landscape greening design. In combination with the topographic and geomorphological conditions as well as the regional and humanistic conditions of the highway tunnel portal area, this paper introduces the cultural landscape and plant greening engineering of highway tunnel entrance by reference to the successful experience of tunnel entrance landscape greening, and puts forward the requirements for landscape and greening technology of highway tunnel entrance in accordance with the provisions of relevant regulations.

scholarly journals Assessing the Equity and Redistributive Effects of Taxation Reforms in Nigeria

2021 ◽  
Author(s):  
Henry C. Edeh
Keyword(s):  
Low Income ◽  
Large Scale ◽  
Value Added ◽  
High Income ◽  
Living Standard ◽  
Middle Income ◽  
Variable Part ◽  
Lump Sum ◽  
Redistributive Effects ◽  
Income Taxpayers

Achieving the Sustainable Development Goals (SDGs) of poverty and inequality reduction through redistribution have indeed become critical concerns in many low- and middle-income countries, including Nigeria. Although redistribution results from the effect of tax revenue collections, micro household-level empirical analyses of the distributional effect of personal income tax (PIT) and value added tax (VAT) reforms in Nigeria have been scarcely carried out. This study for the first time quantitatively assessed both the equity and redistributive effects of PIT and VAT across different reform scenarios in Nigeria. Data used in this study was mainly drawn from the most recent large scale nationally representative Nigeria Living Standard Survey, conducted in 2018/2019. The Kakwani Index was used to calculate and compare the progressivity of PIT and VAT reforms. A simple static micro-simulation model was employed in assessing the redistributive effect of PIT and VAT reforms in the country. After informality has been accounted for, the PIT was found to be progressive in the pre- 2011 tax scheme, but turned regressive in the post-2011 tax scheme. It was also discovered that the newly introduced lump sum relief allowance in the post-2011 PIT scheme accrues more to the high-income than to the low-income taxpayers – confirming the regressivity of the current PIT scheme. However, the study further shows (through counterfactual simulations) that excluding the relatively high-income taxpayers from sharing in the variable part of the lump sum relief allowance makes PIT progressive in the post-2011 scheme. The VAT was uncovered to be regressive both in the pre-2020 scheme, and in the current VAT reform scheme. Further, after putting informality into consideration, the PIT was found to marginally reduce inequality but increase poverty in the pre-2011 scheme. The post-2011 PIT scheme reduced inequality and increased poverty, but by a smaller proportion – confirming a limited redistribution mainly resulting from the concentration of the lump sum relief allowance at the top of the distribution. However, if the variable part of the lump sum relief allowance is provided for ‘only’ the low-income taxpayers below a predefined income threshold, the post-2011 PIT scheme becomes largely redistributive. VAT was uncovered to marginally increase inequality and poverty in the pre-2020 scheme. Though the current VAT scheme slightly increased inequality, it considerably increased poverty in the country. It is therefore suggested that a better tax reform, with well-regulated relief allowance and differentiated VAT rates, will help to enhance the equity and redistribution capacity of the Nigeria tax system.

Sign in / Sign up

Export Citation Format

Share Document