Land surveying is the process of plotting and calculating three-dimensional positions and the relative distances and angles between them. A land surveyor may work on buildings, civil engineering and in calculating land boundaries. There are several individual surveying techniques that are used by land surveyors – this article will review some of the main types.
A geophysical survey is a process that provides information about structures and anomalies that are buried underground or within building structures. A geophysical survey is rather like taking an x-ray of an arm to detect a broken bone; both show the structures that are hidden from view beneath the surface. The main techniques used are magnetometry, electrical resistance, ground-penetrating radar and electromagnetic survey and each of these detect density changes within materials which can then be analysed and graphically displayed.
Geophysical surveys are frequently used in archaeological digs in order to provide the archaeologists with information about buried remains such ancient building structures. The technique can also be applied to existing buildings to identify structural problems that are not visible on the surface.
Another land surveying technique is a geotechnical survey. This type of survey is used to analyse the ground composition to calculate, for example, the various soil and clay layers underneath a building plot. As different soils retain water to different degrees a geotechnical survey can assist in working out how much the ground will swell and contract over the year, what type of foundations are required or whether deep piling is required. Geotechnical surveying can also detect contamination of the soil under a construction site.
Another common form of land survey is the Topographical Survey. This survey is a mapping process that provides accurate and detailed information about plots of land including perimeter dimensions, plot co-ordinates, and elevation of points within the plot. This technique of land survey is an important resource for architects and builders as it helps them develop a detailed understanding of the site before they begin building design and construction. It is also used in civil engineering projects.
An important form of land survey is the boundary survey. This survey can be essential in preventing or resolving boundary disputes. In a boundary survey, accurate measurements and location calculations will be used to compare the situation on the ground with legal boundary lines as described in Deeds and Land Registry records.
The final land survey technique is the hydrographic or bathymetric survey. This technique uses data derived from accurate elevation calculations and measurements to work out flood risk profiles, flood plain areas and drainage routes. This information can be essential in informing flood defense programs and informing risk calculations used by insurance companies. Hydrographic surveys are used by the Environment Agency to provide public data on national flooding risk by post code.
Land surveying is a resource that has a wide range of construction and environmental applications, and is a fundamental part of our everyday construction industry, civil engineering and the overall building process.
