Use of geological mapping tools to improve the hydraulic performance of SuDS

2015 ◽  
Vol 71 (10) ◽  
pp. 1492-1499 ◽  
Author(s):  
Britta Bockhorn ◽  
Knud Erik Strøyberg Klint ◽  
Marina Bergen Jensen ◽  
Ingelise Møller
Keyword(s):  
Hydraulic Performance ◽  
Electrode System ◽  
Geological Mapping ◽  
Geological Heterogeneity ◽  
Shallow Subsurface ◽  
Glacial Origin ◽  
Infiltration Rates ◽  
Geological Information ◽  
Infiltration Tests ◽  
Subsurface Resistivity

Most cities in Denmark are situated on low permeable clay rich deposits. These sediments are of glacial origin and range among the most heterogeneous, with hydraulic conductivities spanning several orders of magnitude. This heterogeneity has obvious consequences for the sizing of sustainable urban drainage systems (SuDS). We have tested methods to reveal geological heterogeneity at field scale to identify the most suitable sites for the placement of infiltration elements and to minimize their required size. We assessed the geological heterogeneity of a clay till plain in Eastern Jutland, Denmark measuring the shallow subsurface resistivity with a geoelectrical multi-electrode system. To confirm the resistivity data we conducted a spear auger mapping. The exposed sediments ranged from clay tills over sandy clay tills to sandy tills and correspond well to the geoelectrical data. To verify the value of geological information for placement of infiltration elements we carried out a number of infiltration tests on geologically different areas across the field, and we observed infiltration rates two times higher in the sandy till area than in the clay till area, thus demonstrating that the hydraulic performance of SuDS can be increased considerably and oversizing avoided if field geological heterogeneity is revealed before placing SuDS.

Groundwater Lowering for Construction of the Kilsby Tunnel – Geological and Geotechnical Interpretation

2021 ◽  
pp. 1-14
Author(s):  
Martin Preene ◽  
Mike Chrimes
Keyword(s):  
Groundwater Flow ◽  
Theoretical Understanding ◽  
Stress Theory ◽  
Glacial Origin ◽  
Buried Channel ◽  
Geological Information ◽  
Ground Conditions ◽  
Glacial Processes ◽  
The Impact ◽  
Groundwater Lowering

The Kilsby Tunnel, constructed in the 1830s, faced severe problems when a section of the tunnel, almost 400 m long, encountered unstable ‘quicksand’ conditions. The engineer for the project, Robert Stephenson, developed an extensive groundwater lowering scheme, unique for the time, using steam engines pumping from multiple shafts, to overcome the quicksand. Modern geological information indicates most of the tunnel was in Middle Lias bedrock, but the ‘quicksand’ section passed through a buried channel of water-bearing sand of glacial origin. In the early 19th century the impact of glacial processes on British geology was not widely accepted and, based on contemporary geological knowledge, Stephenson’s problems appear to be genuine unforeseen ground conditions, not predicted by his experienced advisers. It seems just random chance that trial borings missed the buried channel of sand. The work at Kilsby was two decades before Darcy’s law established the theoretical understanding for groundwater flow, and 90 years before Terzaghi’s effective stress theory described how reducing pore water pressures changed ‘quicksand’ into a stable and workable material. Despite the lack of existing theories, Stephenson used careful observations and interpretation of groundwater flow in the ‘quicksand’ to navigate the tunnel project to a successful conclusion.

Modifications of Physical and Chemical Soil Properties by Application of Treated Petrochemical Effluent

1987 ◽  
Vol 19 (8) ◽  
pp. 195-204
Author(s):  
Z. Simon ◽  
M. Tedesco ◽  
P. Schneider
Keyword(s):  
Soil Properties ◽  
Toxic Metals ◽  
Treatment Plant ◽  
Cumulative Effect ◽  
Effluent Treatment ◽  
High Sodium ◽  
Infiltration Rates ◽  
Low Concentrations ◽  
Infiltration Tests ◽  
Physical And Chemical

Wastewaters generated by Pólo Petroquímico do Sul (South Petrochemical Complex, Triunfo, Brazil) and treated up to tertiary level at SITEL (the integrated effluent treatment plant of the complex) are disposed of on land since 1983 at average rates of 140 m3/ha.day. With the purpose of studying the cumulative effect on soil properties of effluent applied under distinct conditions, four sites have been selected for comparison with adjacent blank areas. Soil samples have been taken for analyses from three different depths (0–30, 30–60 and 60–120 cm) and infiltration tests have been conducted on site. Soil pH, electrical conductivity and extractable Na, Ca and S increased in treated areas, while exchangeable Al and extractable Zn decreased. Exchangeable K and Mg and extractable P, Cu, Mn and B, as well as other toxic metals, did not show significant modifications in comparison with blank areas, with the exception of cadmium. Infiltration rates showed an average fourfold decrease in soils which underwent effluent application, due to increase in pH and exchangeable Na and decrease in Al, all these factors contributing to clay dispersion. The main alterations of forest and grassland environments consisted of trees falling caused by progressive weakening of the root system, due, in turn, to the change to a predominantly anaerobic soil environment and damage to some grass and shrub species, due to the direct impact of sprayed effluent. The observed results are compatible with the average effluent characteristics: low concentrations of toxic metals and negligible contents of residual organic toxicants, together with a high Sodium Adsorption Ratio. With respect to the chemical status of the investigated soils the service life of the disposal system can be extended to decades, provided the discharges of Cd are restricted. As far as infiltration rates are concerned, the results are worrying, however. The soils can be reclaimed by fallowing of the application areas and/or addition of Ca and Mg in order to decrease the Exchangeable Sodium Percentage.

Faulting in Mars Polar Layered deposits modeled by HCA method

2020 ◽  
Author(s):  
Paola Cianfarra ◽  
Costanza Rossi ◽  
Francesco Salvini ◽  
Laura Crispini
Keyword(s):  
Cross Section ◽  
Hydrothermal Activity ◽  
Geological Mapping ◽  
Normal Faults ◽  
Natural Material ◽  
Shallow Subsurface ◽  
Ice Caps ◽  
The North ◽  
Wide Range ◽  
Polar Layered Deposits

<p>The polar layered deposits (PLD) of Mars constitute the water ice stratigraphy of polar spiral troughs up to several kilometers thick (Phillips et al., 2011; Smith et al. 2015). PLD cross section profiles from the Shallow Subsurface Radar (SHARAD) instrument on NASA’s Mars Reconnaissance Orbiter, show the presence of internal discontinuities within these layers (Foss et al., 2017; Putzig et al., 2017). The mechanisms responsible for these deformations are still an open issue (Guallini et al., 2017) and this work represents the contribution of stress-related deformations. Layered ice is simulated by a mesh of cells within a HCA grid build replicating the physical properties and preserving volumes following balanced cross-section principles. Three major types of link exist among adjacent cells: 1. intra-layer relations link cells belonging to the same layer; 2. inter-layer relations regulate the relationships among adjacent layers; 3. discontinuity relations correspond to the presence of ruptures such as faults (Salvini et al., 2001). The HCA method allows to replicate the natural material anisotropies, such as rocks and ice sheet internal layering, and to simulate complex tectonic evolutionary paths (Cianfarra and Salvini, 2016; Cianfarra and Maggi, 2017). The models allow simulating the kinematics of the internal architecture of the layered deposits from both the north and the south Martian ice caps. In particular the observed stratigraphy (geometries and thickness of the ice layers) is replicated as resulting from the relative, normal movement among blocks separated by listric shaped normal faults and minor inversions.</p><p>The used HCA numerical methodology revealed an effective tool to support planetary geological mapping and 3D subsurface geological reconstructions. Through the integration of a net of spatially distributed along- and across- strike (balanced) sections it is possible to simulate the 4D (3D plus time) geological evolution of buried and/or topographic structures. Results have a wide range of applications including the optimal selection of landing sites for scheduled and future planetary exploration missions, as well as unravelling the geological and structural setting of enigmatic features on the planetary surfaces affected, for example, by salt tectonism, volcano-tectonics, tectonically-related hydrothermal activity, fluid storage and release, and ice tectonics.</p>

Wildfire impact on the hydrological conditions of an Alpine slope 

2021 ◽  
Author(s):  
Monica Corti ◽  
Andrea Abbate ◽  
Vladislav Ivanov ◽  
Monica Papini ◽  
Laura Longoni
Keyword(s):  
Soil Properties ◽  
Infiltration Rate ◽  
Hydrogeological Model ◽  
Infiltration Rates ◽  
Mountain Environments ◽  
Hydrogeological Properties ◽  
Infiltration Tests ◽  
Changes Over Time ◽  
The Impact

<p>Wildfire events have severe effects over mountain environments, changing dramatically the local terrain hydrogeological conditions and frequently affecting slope stability. Besides burning vegetation, wildfires induce a modification on soil properties that could result in a decreased capacity of infiltration. This leads to an increase of erosion and, potentially, of the related geohazards, such as flash flooding and debris flows, in the vicinity of the affected sites.</p><p>Past studies found that this reduced infiltration rate changes over time and the original hydrogeological soil properties are expected to recover in as long as 10 years after the wildfire event, depending on the environmental characteristics and on the soil properties of the site.</p><p>Our work aims to investigate the impact of a wildfire on the infiltration conditions of a slope located in the Southern Alps, considering as a case study a wildfire event occurred in Sorico (CO) in December 2018.</p><p>The effects of the wildfire on the infiltration rates and the subsequent recovery of the original hydrogeological properties were evaluated over the span of more than two years after the event. Infiltration tests were performed both within the most affected area as well as in the nearest unburnt area. Results were then correlated with precipitation and satellite imagery data in order to retrieve a recovery factor, necessary for the calibration of a simple 1D hydrogeological model.</p>

A survey of current trends in near-surface electrical and electromagnetic methods

Geophysics ◽  
2006 ◽  
Vol 71 (5) ◽  
pp. G249-G260 ◽  
Author(s):  
Esben Auken ◽  
Louise Pellerin ◽  
Niels B. Christensen ◽  
Kurt Sørensen
Keyword(s):  
Precision Agriculture ◽  
Cost Effective ◽  
Geological Mapping ◽  
Easy Access ◽  
Data Sets ◽  
Near Surface ◽  
Shallow Subsurface ◽  
Effective Manner ◽  
Geotechnical Investigations ◽  
New Interpretation

Electrical and electromagnetic (E&EM) methods for near-surface investigations have undergone rapid improvements over the past few decades. Besides the traditional applications in groundwater investigations, natural-resource exploration, and geological mapping, a number of new applications have appeared. These include hazardous-waste characterization studies, precision-agriculture applications, archeological surveys, and geotechnical investigations. The inclu-sion of microprocessors in survey instruments, development of new interpretation algorithms, and easy access to powerful computers have supported innovation throughout the geophysical community and the E&EM community is no exception. Most notable are development of continuous-measurement systems that generate large, dense data sets efficiently. These have contributed significantly to the usefulness of E&EM methods by allowing measurements over wide areas without sacrificing lateral resolution. The availability of these luxuriant data sets in turn spurred development of interpretation algorithms, including: Laterally constrained 1D inversion as well as innovative 2D- and 3D-inversion methods. Taken together, these developments can be expected to improve the resolution and usefulness of E&EM methods and permit them to be applied economically. The trend is clearly toward dense surveying over larger areas, followed by highly automated, post-acquisition processing and interpretation to provide improved resolution of the shallow subsurface in a cost-effective manner.

scholarly journals Application of UAV in Topographic Modelling and Structural Geological Mapping of Quarries and Their Surroundings—Delineation of Fault-Bordered Raw Material Reserves

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 489 ◽  
Author(s):  
Ákos Török ◽  
Gyula Bögöly ◽  
Árpád Somogyi ◽  
Tamás Lovas
Keyword(s):  
Remote Sensing ◽  
Laser Scanning ◽  
Field Measurements ◽  
Fault Zones ◽  
Geological Mapping ◽  
Raw Material ◽  
Surface Model ◽  
Entire Study ◽  
Geological Information ◽  
Major Fault

A 3D surface model of an active limestone quarry and a vegetation-covered plateau was created using unmanned aerial vehicle (UAV) technique in combination with terrestrial laser scanning (TLS). The aim of the research was to identify major fault zones that dissect the inaccessible quarry faces and to prepare a model that shows the location of these fault zones at the entire study area. An additional purpose was to calculate reserves of the four identified lithological units. It was only possible to measure faults at the lowermost two meters of the quarry faces. At the upper parts of the quarry and on the vegetation-covered plateau where no field geological information was available, remote sensing was used. Former logs of core drillings were obtained for the modelling of the spatial distribution of four lithological units representing cover beds and various quality of limestone reserves. With the comparison of core data, field measurements and remote sensing, it was possible to depict major faults. Waste material volumes and limestone reserves were calculated for five blocks that are surrounded by these faults. The paper demonstrates that, with remote sensing and with localised control field measurements, it is possible: (a) to provide all geometric data of faults and (b) to create a 3D model with fault planes even at no exposure or at hardly accessible areas. The surface model with detected faults serves as a basis for calculating geological reserves.

scholarly journals GIS IN URBAN GEOLOGY: THE CASE STUDY OF NAFPLIO, ARGOLIS PREFECTURE, GREECE

2017 ◽  
Vol 43 (3) ◽  
pp. 1559
Author(s):  
A.D. Zervakou ◽  
P. Tsombos
Keyword(s):  
Mineral Exploration ◽  
Geological Mapping ◽  
Capital City ◽  
Urban Geology ◽  
Digital Products ◽  
Geophysical Research ◽  
Suburban Areas ◽  
Geological Conditions ◽  
Geological Information ◽  
Gis Environment

The aggregation of population in big cities leads to the concentration of human activities, overconsumption of natural resources and urban growth without spatial planning and sustainable management. As a result, urban societies are exposed to various dangers and threats with economic, social, ecological, and environmental impacts on the urban surroundings. Problems associated with urban development are related to the existing geological conditions. Therefore, the provision of appropriate geological information about the urban environment is essential for every sustainable urban planning. The first systematic recording, codification and documentation of “Urban Geology” geothematic information in Greece was implemented by the Institute of Geology and Mineral Exploration (I.G.M.E.) in the framework of the project called “Collection, codification and documentation of geothematic information for urban and suburban areas in Greece - pilot applications”. Through the implementation of this project, geological mapping, geotechnical, geochemical, geophysical research and measurements took place at four pilot cities of Greece. Nafplio, the capital city of Argolis prefecture, was one of them. During the project, all compiled data were stored and processed in specially designed geodatabases in GIS environment in order to produce multifunctional geothematic maps and other digital products (DEMs, 2D - 3D surfaces).

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