SURVEY



By definition, surveying is the science of gathering, determining, recording and measuring the relative size of human made and natural features on the earth`s surface. Surveying is the science of measuring and record distances, angles and heights on the Earth’s surface to obtain data from which accurate plans and maps are made.

Surveying is also the art and science of making or taking measurements both linear and angular on the earth’s surface at different positions for the purpose of producing a plan or map. In other definition; surveying (land surveying) is a science of measuring and recording distances, angles and height on earth’s surface to obtain data by which accurate plans and maps of parts of surface of the earth are made

Angular measurement means measuring the distance from a given reference point to an observed object. The distance is measured in a clockwise direction from North. Linear measurement is the distance measured along the surface of the ground such a s a horizontal distance. Process of surveying involves taking pictures of general view of area of what is required to be surveyed before any type of survey is carried out. Therefore, all process of surveying at the end aims at determining distances, heights, gradients, locations and making shapes

Purpose of Surveying:
There are only two major purposes of survey namely:
  1. To prepare maps and plans
  2. To calculate areas and distance

Types of Major Surveys
There are two main types of surveying, namely:
a) Geodetic Surveying (geodes): is the branch of surveying in which, measurement of the curvature of the earth is taken into consideration. Generally carried out on a national basis using triangulation method. This kind of survey is carried out with the aim of knowing the Earth’s shape and size (the Earth's configuration).
b) Plane Surveying:  is the type of survey in which the measurements are taken as if surface of the earth is flat. This does not consider curvature of the earth. This kind of survey is conducted with the aim of preparing a legal document such as house plans, town or city boundaries, etc. It is mainly used for ownership purposes. 

General Types of Surveying
Other types of surveying which overlap with geodetic and plane surveying are into four:
(i)Topographical Surveying: deals with measurement of physical features of the earth’s surface (either natural or man-made features). This kind of survey is carried out for the purpose of preparing topographical maps. Topographical maps are those maps whose contents include both man-made features such as linear features (roads, railways, telephone lines, water systems, and electricity poles) and natural features such as rivers, oceans, mountains, etc.
 (ii) Cadastral surveying: this is the survey that deals with measurement of boundaries e.g. boundaries of town, village, or countries. Or are undertaken to define and record boundaries of properties, legislative areas and countries

(iii) Engineering Surveying: Is the survey that under taken to provide special information for construction projects. Also it is known as site-surveys. This kind of survey is conducted for the building and construction layout of railways, bridges and roads. 

(iv) Geographical Information System (G. I. S.): It is the modern survey that under taken by using electronic equipment like Quantum Geographical Information System (Q.G.I.S). This kind of survey is conducted with the aim of knowing the distribution of rocks and minerals under the Earth’s surface. 

Importance of  Surveying
 Surveying is important for social and economic activities as named bellow:

1.    Plans making: This includes town planning settlement planning
2.    Help in finding relative position and size of features of the land surface.
3.    Uses for construction, e.g.  archtecture and construction of buildings.
4.    Uses for boundary and putting marks on the land.
5.    Source of income. Surveyors land to earn more money brought surveying.
6.    1. It help to prepare a topographical map which shows the hills, valleys, rivers, villages, towns, forests, etc. of a country.
7.    It helps to prepare a cadastral map showing the boundaries of the fields, houses and other properties.
8.    It help to prepare an engineering map which shows the details of engineering works such as roads, railways, reservoirs, irrigation canals, etc.
9.    It help to prepare a military map showing the road and railway communications with different parts of a country.
10. It helps to prepare a contour map to determine the capacity of a reservoir and to find the best possible route for roads, railways, etc.
11. It helps to prepare a geological map showing areas including underground resources.
12. It helps to prepare an archaeological map including places ancient relics exist.

Method of  Surveying (Elements of Surveying):
The instrument used during surveying can simply determine the method of survey. Geographical surveying or measurement involves the use of the following methods:

1.    Chain or tape survey.
2.    Prismatic compass survey.
3.    Plane table survey.
4.    Levelling survey.

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