Unit
VIII: Site Investigation(6 hrs)
8.1 Elements of an investigation, types of site investigation (Direct and indirect methods)
The elements of an investigation involve gathering information and assessing a site to understand its characteristics. Site investigations can be conducted using direct and indirect methods.
Direct Methods: Direct methods involve physically examining the site and collecting data through fieldwork. This can include activities such as drilling boreholes, conducting soil and rock sampling, performing geophysical surveys, and monitoring groundwater levels. Direct methods provide firsthand information about the site's conditions.
Indirect Methods: Indirect methods rely on existing data and sources of information without direct physical contact with the site. This can involve studying historical records, analyzing aerial photographs, using remote sensing techniques like satellite imagery and SAR images, and reviewing geological and engineering geological maps. Indirect methods are useful for obtaining preliminary information about the site or when direct access is limited.
By combining direct and indirect methods, investigators can gather comprehensive data about a site, enabling them to make informed decisions for various projects such as infrastructure development, environmental assessments, or geological studies.
8.2 Study of topographic, geological and engineering geological maps, satellite imagery and SAR image
The study of topographic, geological, and engineering geological maps, satellite imagery, and Synthetic Aperture Radar (SAR) images provides valuable information about a site or an area:
Topographic Maps: Topographic maps depict the physical features of the land, including elevation contours, rivers, roads, and vegetation. They help in understanding the terrain, slope characteristics, drainage patterns, and identifying potential areas of concern or constraints for engineering projects.
Geological Maps: Geological maps illustrate the distribution of different rock types, geological formations, faults, and other geological features. They provide insights into the subsurface geology, including the presence of valuable minerals, geological hazards, and the suitability of the site for specific purposes like construction or resource extraction.
Engineering Geological Maps: Engineering geological maps focus on the geotechnical properties of the site. They provide information on soil types, rock quality, stability, groundwater conditions, and other relevant factors that influence engineering design and construction. These maps help in assessing the suitability and potential challenges of the site for infrastructure projects.
Satellite Imagery: Satellite imagery offers a bird's-eye view of the Earth's surface. It provides high-resolution images that can show land cover, land use patterns, vegetation distribution, and changes over time. Satellite imagery is useful for identifying natural features, urban development, and monitoring environmental changes in a wide area.
SAR Images: Synthetic Aperture Radar (SAR) images use radar technology to capture data about the Earth's surface. SAR images can penetrate cloud cover, making them suitable for all-weather and day/night observations. SAR images are used to detect ground movement, monitor terrain deformations, assess flood extents, and analyze vegetation health.
By studying these maps and images, geologists, engineers, and researchers can gain a better understanding of the site's characteristics, potential risks, and opportunities. This information is vital for various applications, such as urban planning, infrastructure development, resource exploration, and environmental monitoring.
8.4 Geological investigation for dam, reservoir, road, building, bridges and underground excavation
