scholarly journals A Groundwater Modeling on Hard Rock Terrain by using Visual Modflow Software for Bangalore North, Karnataka, India

2019 ◽  
Vol 8 (12) ◽  
pp. 1473-1478
Keyword(s):  
Groundwater Modeling ◽  
Transient State ◽  
Distributed Model ◽  
Visual Modflow ◽  
Pumping Wells ◽  
Digital Elevation ◽  
Geological Information ◽  
Set Up ◽  
Elevation Model ◽  
Observation Wells

The present study investigated through mathematical modelling techniques (using Modflow) for the Bengaluru North zone. The present study carried out in Bengaluru North Taluk lies in between 12° 52’ N to 130 15’ N, 770 22’ E to 770 50’ E to assess the changes in groundwater heads due to enormous pressure on water availability (especially in groundwater) in the study area for a scientific planning and management of water resources. The present study carried out using mathematical distributed model Modflow, to set up, execute the model, requires several data of which study area boundary (.shp format), geological information to represent the geological layers in to the model using Digital Elevation Model (DEM) obtained from Cartosat I Ver. 3R (Bhuvan site), pumping wells, observation wells etc. Shows the head variation in the study area before adding pumping wells and after adding pumping wells. The final observed and simulated results of the groundwater heads in the Bengaluru North taluk under transient state condition

scholarly journals Groundwater Modelling in Urban Development to Achieve Sustainability of Groundwater Resources: A Case Study of Semarang City, Indonesia

Water ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1395
Author(s):  
Weicheng Lo ◽  
Sanidhya Nika Purnomo ◽  
Dwi Sarah ◽  
Sokhwatul Aghnia ◽  
Probo Hardini
Keyword(s):  
Groundwater Modeling ◽  
Groundwater Resources ◽  
Management Strategies ◽  
Production Capacity ◽  
Transient State ◽  
Deep Wells ◽  
Temporal And Spatial ◽  
Observation Wells ◽  
Control Management

Since 1900, Semarang City has been meeting its industrial water needs by pumping groundwater through its underlying aquifers. The trend toward exploiting groundwater resources has driven the number of deep wells and their production capacity to increase, and therefore leads to the water table to drop from time to time, which has been marked as one of the primary causes of land subsidence there. The main aim of the current study was to numerically model the temporal and spatial evolution of groundwater table under excess abstraction so that a groundwater management strategy can be accordingly drawn up for ensuing the sustainability of groundwater resources in the future. A series of numerical simulations were carried out to take into account hydrogeological data, artificial and natural discharges of deep wells, and boundary effects in Semarang City. The groundwater modeling is calibrated under two flow conditions of the steady state from 1970 to 1990 and the transient state from 1990 to 2005 for six observation wells distributed in Semarang City. Four scenarios that reflect potential management strategies were developed, and then their effectiveness was systematically investigated. The results of our study indicate that the implementation of proper groundwater control management and measure is able to restore the groundwater level to rise back in Semarang City, and in turn achieve the sustainability of groundwater resources.

scholarly journals Assessing ice-cliff backwasting and its contribution to total ablation of debris-covered Miage glacier, Mont Blanc massif, Italy

2014 ◽  
Vol 60 (219) ◽  
pp. 3-13 ◽  
Author(s):  
T.D. Reid ◽  
B.W. Brock
Keyword(s):  
Field Measurements ◽  
Distributed Model ◽  
Short Term ◽  
Model Calculations ◽  
Digital Elevation ◽  
Debris Cover ◽  
Continuous Surface ◽  
Elevation Model ◽  
Miage Glacier ◽  
Mont Blanc Massif

AbstractContinuous surface debris cover strongly reduces the ablation of glaciers, but high melt rates may occur at ice cliffs that are too steep to hold debris. This study assesses the contribution of ice-cliff backwasting to total ablation of Miage glacier, Mont Blanc massif, Italy, in 2010 and 2011, based on field measurements, physical melt models and mapping of ice cliffs using a high-resolution (1 m) digital elevation model (DEM). Short-term model calculations closely match the measured melt rates. A model sensitivity analysis indicates that the effects of cliff slope and albedo are more important for ablation than enhanced longwave incidence from sun-warmed debris or reduced turbulent fluxes at sheltered cliff bases. Analysis of the DEM indicates that ice cliffs account for at most 1.3% of the 1 m pixels in the glacier’s debris-covered zone, but application of a distributed model indicates that ice cliffs account for ~7.4% of total ablation. We conclude that ice cliffs make an important contribution to the ablation of debris-covered glaciers, even when their spatial extent is very small.

scholarly journals TanDEM-X PolarDEM 90 m of Antarctica: Generation and error characterization

2021 ◽  
Author(s):  
Birgit Wessel ◽  
Martin Huber ◽  
Christian Wohlfart ◽  
Adina Bertram ◽  
Nicole Osterkamp ◽  
...  
Keyword(s):  
Ice Cloud ◽  
Amplitude Data ◽  
Open Sea ◽  
Digital Elevation ◽  
X Band ◽  
Error Characterization ◽  
Antarctic Continent ◽  
Absolute Height ◽  
Set Up ◽  
Elevation Model

Abstract. We present the generation and validation of an updated version of the TanDEM-X Digital Elevation Model (DEM) of Antarctica: the TanDEM-X PolarDEM 90 m of Antarctica. Improvements compared to the global TanDEM-X DEM version include filling of gaps with newer acquisitions, interpolating of smaller voids, smoothing of noisy areas and replacing frozen or open sea areas with geoid undulations. For the latter, a new semi-automatic editing approach allowed the delineation of the coastline from DEM and amplitude data. Finally, the DEM was transformed into the cartographic Antarctic Polar Stereographic projection with a homogeneous metric spacing in northing and easting of 90 meters. As X-Band synthetic aperture radar (SAR) penetrates the snow and ice pack by several meters a new concept for absolute height adjustment was set up that relies on areas with stable penetration conditions and on ICESat (Ice, Cloud, and land Elevation Satellite) elevations. After DEM generation and editing, a sophisticated height error characterization of the whole Antarctic continent with ICESat and IceBridge data was carried out and a validation over blue ice achieved a mean vertical height error of just −0.3 m ± 2.5 m standard deviation. The filled and edited Antarctic TanDEM-X PolarDEM 90 m is outstanding due to its accuracy, homogeneity and coverage completeness. It is freely available for scientific purposes and provides a high-resolution dataset as basis for polar research, such as ice velocity, mass balance estimation or ortho-rectification.

3D geological modelling of the western Aar Massif (external Central Alps, Switzerland)

2020 ◽  
Author(s):  
Ferdinando Musso Piantelli ◽  
Marco Herwegh ◽  
Alfons Berger ◽  
Michael Wiederkehr ◽  
Eva Kurmann ◽  
...  
Keyword(s):  
Digital Elevation Model ◽  
Cross Sections ◽  
3D Model ◽  
Two Dimensional ◽  
Central Alps ◽  
Digital Elevation ◽  
Geological Information ◽  
Aar Massif ◽  
Elevation Model ◽  
Tectonic Boundaries

<p>3D modelling of complex and irregular geological bodies is an expanding discipline that combines two-dimensional cartographic and structural data managed with GIS technology. This study presents a complete workflow developed to process geological information to build a 3D model of major stratigraphic, structural and tectonic boundaries. The investigated area is located in the western part of the Aar Massif (external Central Alps, Switzerland) characterized by pronounced topographic (600–<4000 m) relief, making it prone for surface based 3D depth constructions. The workflow comprises four major steps:</p><p>(1)  <strong>Generation of 2D polylines in a map view</strong>: a two-dimensional dataset of sequences of polylines has been generated in ArcGIS (10.3.1) defining the starting dataset for the major stratigraphic and tectonic boundaries of the bedrock units. This dataset has been compiled and integrated by using: (i) GeoCover vector datasets 1:25 000 of the Swiss Geological Survey; (ii) The Geological Special Map 1:100 000 of the Aar Massif and the Tavetsch and Gotthard Nappes of the Swiss Geological Survey; (iii) data from literature; and (iv) additional field work conducted for this study in key-locations.</p><p>(2) <strong>Projection of 2D information onto 3D digital elevation model</strong>: with the 3D structural modelling software Move (Petex/Midland Valley; 2019.1) the boundaries have then been projected on a digital elevation model (swissALTI3D) with 2 m resolution.</p><p>(3) <strong>Construction of tectonic cross sections</strong>: the use of geometric arguments as well as structural measurements allows for projection of these boundaries into a dense regularly spaced network of 2D cross-sections.</p><p>(4) <strong>Interpolation of 3D surfaces</strong>: the surface and cross-sections boundaries can be interpolated by applying 3D projection and meshing techniques resulting in a final 3D structural model.</p><p>Generally, steps (2–4) require iterative adaptations particularly in the case of surface areas being covered by glaciers or unconsolidated Quaternary sediments. In the model, special emphasis is given to visualize the current structural disposition of the western Aar Massif as well as the relative geometric and overprinting relationships of the deformation sequence that shaped the investigated area throughout the Alpine deformation. Finally, since in the investigated area underground data are scarce, an assessment of the relative uncertainties related to input data and is intended to be performed following the approach proposed by Baumberger (2014) and Ferńandez (2005). The workflow presented here offers the chance to gain validation approaches for domains only weakly constrained or with no surface data available, by generating a 3D model that integrates all accessible geological information and background knowledge.</p><p> </p><p>REFERENCES</p><p>Baumberger, R. (2014): Quantification of Lineaments: Link between internal 3D structure and surface evolution 328 of the Hasli valley (Aar massif, central alps, Switzerland), University of Bern, PhD Thesis, unpublished.</p><p>Ferńandez, O. (2005): Obtaining a best fitting plane through 3D georeferenced data, Journal of Structural Geology 27, pp. 855–858</p>

scholarly journals Integration and Visualization of Mineralogical and Topographical Information Derived from ASTER and DEM Data

2019 ◽  
Vol 11 (2) ◽  
pp. 162 ◽  
Author(s):  
Kana Kurata ◽  
Yasushi Yamaguchi
Keyword(s):  
Carbonate Rocks ◽  
Thermal Emission ◽  
Color Image ◽  
Point Of View ◽  
Digital Elevation ◽  
Hsv Color Model ◽  
Geological Information ◽  
Hydrothermal Alteration Zones ◽  
Elevation Model ◽  
Silicate Rocks

This paper proposes a method of combining and visualizing multiple lithological indices derived from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and topographical information derived from digital elevation model (DEM) data in a single color image that can be easily interpreted from a geological point of view. For the purposes of mapping silicate rocks, carbonate rocks, and clay minerals in hydrothermal alteration zones, two new indices derived from ASTER thermal infrared emissivity data were developed to identify silicate rocks, and existing indices were adopted to indicate the distribution of carbonate rocks and the species and amounts of clay mineral. In addition, another new method was developed to visualize the topography from DEM data. The lithological indices and topographical information were integrated using the hue–saturation–value (HSV) color model. The resultant integrated image was evaluated by field survey and through comparison with the results of previous studies in the Cuprite and Goldfield areas, Nevada, USA. It was confirmed that the proposed method can be used to visualize geological information and that the resulting images can easily be interpreted from a geological point of view.

scholarly journals TanDEM-X PolarDEM 90 m of Antarctica: generation and error characterization

2021 ◽  
Vol 15 (11) ◽  
pp. 5241-5260
Author(s):  
Birgit Wessel ◽  
Martin Huber ◽  
Christian Wohlfart ◽  
Adina Bertram ◽  
Nicole Osterkamp ◽  
...  
Keyword(s):  
Data Set ◽  
High Resolution Data ◽  
Ice Cloud ◽  
Amplitude Data ◽  
Open Sea ◽  
Digital Elevation ◽  
Error Characterization ◽  
Antarctic Continent ◽  
Set Up ◽  
Elevation Model

Abstract. We present the generation and validation of an updated version of the TanDEM-X digital elevation model (DEM) of Antarctica: the TanDEM-X PolarDEM 90 m of Antarctica. Improvements compared to the global TanDEM-X DEM version comprise filling gaps with newer bistatic synthetic aperture radar (SAR) acquisitions of the TerraSAR-X and TanDEM-X satellites, interpolation of smaller voids, smoothing of noisy areas, and replacement of frozen or open sea areas with geoid undulations. For the latter, a new semi-automatic editing approach allowed for the delineation of the coastline from DEM and amplitude data. Finally, the DEM was transformed into the cartographic Antarctic Polar Stereographic projection with a homogeneous metric spacing in northing and easting of 90 m. As X-band SAR penetrates the snow and ice pack by several meters, a new concept for absolute height adjustment was set up that relies on areas with stable penetration conditions and on ICESat (Ice, Cloud, and land Elevation Satellite) elevations. After DEM generation and editing, a sophisticated height error characterization of the whole Antarctic continent with ICESat data was carried out, and a validation over blue ice achieved a mean vertical height error of just −0.3 m ± 2.5 m standard deviation. The filled and edited Antarctic TanDEM-X PolarDEM 90 m is outstanding due to its accuracy, homogeneity, and coverage completeness. It is freely available for scientific purposes and provides a high-resolution data set as basis for polar research, such as ice velocity, mass balance estimation, or orthorectification.

Application of GIS on Rapid Evaluation for Potential Portal Areas of Tunnels

2013 ◽  
Vol 479-480 ◽  
pp. 1056-1060 ◽  
Author(s):  
Iau Teh Wang
Keyword(s):  
Potential Hazard ◽  
Infinite Slope ◽  
Planning Stage ◽  
Digital Elevation ◽  
Set Up ◽  
Elevation Model ◽  
The Stability ◽  
Slice Method ◽  
Potential Area ◽  
Tunnel Portal

Stability of tunnel portal depends on lots of factors, such as existing topography, engineering geology, hydrogeology as well as portal layout designated and stability measurements adopted, etc. Location of portals is one of the most important issues for route selection and planning stage of tunnel engineering. Thus, it is usually a mission of well-experienced engineers and also a time-consuming task. Recently, the well development of geographic information system (GIS) provides a better way to assess the slope stability of potential area for tunneling. There are great numbers of researches focusing on the evaluation on potential hazard or stability degree of existing slopes; however, the potential instability caused by possible excavation due to layout designation is seldom to be taken into account in these researches. Consequently,the present work aims to set up a GIS based method, considering the possible impacts caused by portal excavation, to quickly assess the stability of portal. First, the conventional profiles used in portals are taken into account and typical excavated slope ratios are introduced. Then, based on the digital elevation model, the potential excavated area for a location with considered elevation, said the critical wedge, can be determined accordingly. The analysis method for infinite slope is then applied to evaluation the stability of the critical wedge. Comparison with the results from slice method shows that the proposed method provides a reasonable estimation. Application to a tunnel with 6 portals, some instability occurred during construction, meets well with the situations. Using the embedded function of GIS, the safety factor then can be obtained by means of the proposed method. As various slope ratios and distinct elevation are considered, the analyzed results provide valuable information for tunnel portal selection.

scholarly journals Impact of DEM Resolution and Spatial Scale: Analysis of Influence Factors and Parameters on Physically Based Distributed Model

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Hanchen Zhang ◽  
Zhijia Li ◽  
Muhammad Saifullah ◽  
Qiaoling Li ◽  
Xiao Li
Keyword(s):  
Influence Factors ◽  
Distributed Model ◽  
Small Scale ◽  
Simulation Accuracy ◽  
Digital Elevation ◽  
Physically Based ◽  
Simulation Results ◽  
Distributed Hydrological Models ◽  
Elevation Model ◽  
Sensitive Parameters

Physically based distributed hydrological models were used to describe small-scale hydrological information in detail. However, the sensitivity of the model to spatially varied parameters and inputs limits the accuracy for application. In this paper, relevant influence factors and sensitive parameters were analyzed to solve this problem. First, a set of digital elevation model (DEM) resolutions and channel thresholds were generated to extract the hydrological influence factors. Second, a numerical relationship between sensitive parameters and influence factors was established to define parameters reasonably. Next, the topographic index (TI) was computed to study the similarity. At last, simulation results were analyzed in two different ways: (1) to observe the change regularity of influence factors and sensitive parameters through the variation of DEM resolutions and channel thresholds and (2) to compare the simulation accuracy of the nested catchment, particularly in the subcatchments and interior grids. Increasing the grid size from 250 m to 1000 m, the TI increased from 9.08 to 11.16 and the Nash-Sutcliffe efficiency (NSE) decreased from 0.77 to 0.75. Utilizing the parameters calculated by the established relationship, the simulation results show the same NSE in the outlet and a better NSE in the simple subcatchment than the calculated interior grids.

scholarly journals Simulation and comparison of stream power in-channel and on the floodplain in a German lowland area

2014 ◽  
Vol 62 (2) ◽  
pp. 133-144 ◽  
Author(s):  
Song Song ◽  
Britta Schmalz ◽  
Nicola Fohrer
Keyword(s):  
Swat Model ◽  
Peak Discharge ◽  
Stream Power ◽  
Stream Discharge ◽  
Bankfull Discharge ◽  
Digital Elevation ◽  
Lowland Area ◽  
Set Up ◽  
Elevation Model

Abstract Extensive lowland floodplains cover substantial parts of the glacially formed landscape of Northern Germany. Stream power is recognized as a force of formation and development of the river morphology and an interaction system between channel and floodplain. In order to understand the effects of the river power and flood power, HEC-RAS models were set up for ten river sections in the Upper Stör catchment, based on a 1 m digital elevation model and field data, sampled during a moderate water level period (September, 2011), flood season (January, 2012) and dry season (April, 2012). The models were proven to be highly efficient and accurate through the seasonal roughness modification. The coefficients of determination (R2) of the calibrated models were 0.90, 0.90, 0.93 and 0.95 respectively. Combined with the continuous and long-term data support from SWAT model, the stream power both in-channel and on the floodplain was analysed. Results show that the 10-year-averaged discharge and unit stream power were around 1/3 of bankfull discharge and unit power, and the 10-year-peak discharge and unit stream power were nearly 1.6 times the bankfull conditions. Unit stream power was proportional to the increase of stream discharge, while the increase rate of unit in-channel stream power was 3 times higher than that of unit stream power on the floodplain. Finally, the distribution of the hydraulic parameters under 10-years-peak discharge conditions was shown, indicating that only 1-10% of flow stream was generated by floodplain flow, but 40-75% volume of water was located on the floodplain. The variation of the increasing rate of the stream power was dominated by the local roughness height, while the stream power distributed on the floodplain mainly depended on the local slope of the sub-catchment.

scholarly journals Evaluation of DEM generation accuracy from UAS imagery

2014 ◽  
Vol XL-5 ◽  
pp. 529-536 ◽  
Author(s):  
M. Santise ◽  
M. Fornari ◽  
G. Forlani ◽  
R. Roncella
Keyword(s):  
Ground Level ◽  
Test Area ◽  
Flying Height ◽  
Test Field ◽  
Aerial Photogrammetry ◽  
New Family ◽  
Digital Elevation ◽  
Automated Processing ◽  
Set Up ◽  
Elevation Model

The growing use of UAS platform for aerial photogrammetry comes with a new family of Computer Vision highly automated processing software expressly built to manage the peculiar characteristics of these blocks of images. It is of interest to photogrammetrist and professionals, therefore, to find out whether the image orientation and DSM generation methods implemented in such software are reliable and the DSMs and orthophotos are accurate. On a more general basis, it is interesting to figure out whether it is still worth applying the standard rules of aerial photogrammetry to the case of drones, achieving the same inner strength and the same accuracies as well. With such goals in mind, a test area has been set up at the University Campus in Parma. A large number of ground points has been measured on natural as well as signalized points, to provide a comprehensive test field, to check the accuracy performance of different UAS systems. In the test area, points both at ground-level and features on the buildings roofs were measured, in order to obtain a distributed support also altimetrically. Control points were set on different types of surfaces (buildings, asphalt, target, fields of grass and bumps); break lines, were also employed. The paper presents the results of a comparison between two different surveys for DEM (Digital Elevation Model) generation, performed at 70 m and 140 m flying height, using a Falcon 8 UAS.

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