A cadastral survey is a survey that defines and quantitatively sets land boundaries for legal purposes, usually between pieces of property. It is sometimes used on a larger scale to define borders between governmental jurisdictions, from boundaries between small municipalities up to international borders. The term cadastral is taken from a French word that is derived from Latin and Greek origins.
Land surveyors use a cadastral survey to give a definitive description of a parcel of land. A cadastral survey defines the borders of a parcel of land in relation to surrounding parcels and describes them in such a way as to be applicable to physical geography. When a property line or other boundary is in dispute, a cadastral survey can help determine the proper disposition of any disputed territory or land. While a cadastral survey uses techniques grounded in science and engineering, its primary purpose is a legal one, rather than scientific.
Any survey of this type must rely on past records and previous surveys for information. A surveyor performing a cadastral survey uses all information available which may include previous maps, charts, diagrams, and legal documents. A legal document such as a deed may describe in legal terms the boundaries of a land parcel, but a survey is needed to give those legal definitions and coordinates a physical meaning. In many cases, there may be physical evidence from previous surveys such as survey markers or other geographical features used as such. A cadastral survey may also be needed when a land parcel is divided, to properly define the new boundaries.
The details of such a survey will be compiled in a document or a collection of documents called a cadastre. A cadastre contains the technical information of a cadastral survey such as dimensions, area and exact descriptions of all borders and property lines as well as information concerning land use data, the parcel's ownership, both current and historical, and its position. Other data such as value are commonly included, for tax purposes, in many jurisdictions. In some areas of the world, the deed or title to a land parcel may be part of the cadastre.
In the United States, the federal government maintains, as part of its Department of the Interior, a division called the Bureau of Land Management (BLM). This agency is responsible for performing and maintaining records for cadastral surveys of the public lands. The BLM carries out surveys regularly for a variety of reasons, such as when the federal government buys or sells land, grants land-use rights for corporations and individuals, or describes boundaries for new parks or preserves.