GEOGRAPHY FORM 5- INTRODUCTION TO SURVEYING

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GEOGRAPHY FORM 5- INTRODUCTION TO SURVEYING

SURVEYING

Surveying is an art or a science of measuring and recording distances, shape and heights in the field on the earth surface from which maps or plans can be developed.

Or is an art or a science of making measurements of natural and man made features on the earth surface made on the earth surface in the field areas help the features. The collected information from field areas about the natural and artificial features are finally represented in a form of a map or a pan of which drawn at a specified scale

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VARIABLES USED IN PROCESS OF SURVEY

The conducted surveys are of wide range and thus fall into different types as reasonably classified. The wide range of survey classified according o the size of areas whose measurements determined and according to specific objectives.

By considering the size and nature of the surface areas that has been surveyed or would be surveyed, the art of survey is divided into two variables

·         (i)Geodetic survey

·         (ii)Plane survey

Geodetic survey

It a type of survey which covers such larger areas like the whole of the earth surface, a continent or a country and takes into account of the curvature of the surface area. Geodetic survey is mostly used to establish Saturn points (bench marks )

Plane survey

It is types of survey used for the smaller areas of which the surface is considered flat and the earth curvature is not taken into consideration. Areas surveyed are not more than 10km X 10km size

Survey according to the specific objective include the following significant types

-Topographical survey

·         -Engineering survey

·         -Geological (mining) survey

·         -Hydrological survey

·         -Photogrammetric survey

 

Topographical survey

It is a survey by which the topographical features of the earths surface such as road, revivers, mountains plateaus ocean building lakes, vegetation and others are measured and whose measurements used to develop maps or plans which show their relative positions both horizontally and vertical. Maps developed after the conduct of topographical survey are known a topographical maps

GEOGRAPHY FORM 5- INTRODUCTION TO SURVEYING

Cadastral survey

Cadastral survey is also known as boundary survey. It is a kind of survey conducted with an aim of preparing legal documents on boundaries of towns, cities, industries for owner ship purposes. i.e A sort of survey carried out to produce plans which shown properties boundaries. It is mostly conducted to develop administrative areas.

 

Engineering survey

It is also as built up survey. It is a kind of survey which provides details (special information) for construction purpose. The construction can be of buildings, reads, railways, bridges, water dam etc. They are commonly carried of during and after planning the construction of engineering projects.

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Geological (mining) survey

It is a kind of survey conducted by the geologists with the aim of realizing the distribution of rocks and their content. Or all surveys for mining works on the earth or under ground.

 

Hydrographical survey

It is a sort of survey for water areas particularly seas and lake, They are carried out to determine the depth of water bodies at different points and nature of the bottom of the sea. These are commonly carried out for harbor construction, oil drilling and natural gas exploration as well as exploitation at sea area

Note

With all types of survey, topographical survey is of the major concern in our level. This is one of the major concerning in our level. This is conducted by different ways which include the following

·         Chain survey

·         Plane table survey

·         Prismatic survey

·         Leveling

 

IMPORTANCE OF CONDUCTING SURVEY

·         (i)To determine altitude size and distance of different areas

·         (ii)To establish position location of both natural and artificial features

·         (iii)They are potential for maps construction. Details on heights bearing, distance and size of features for areas which appear on maps derived from survey works.

·         (iv)To plan and control various kinds of engineer projects such as roads, railways, buildings canals and dams contraction

·         (v)To develop data bank of land and natural resources which aid in developing and management of environment

 

SURVEYING PROCESS

The conduct of surveying particularly topographical survey in the field area, should involves the following three significant steps

·         Reconnaissance survey

·         Observation and measurement

·         Presentation or plotting of the data

 

 Reconnaissance survey

The site whose details to be taken by conducting survey should be pre visited. This is commonly known as reconnaissance survey and it is defined as preliminary survey by which surveyor takes a general picture about the areas into his or her mind by working all over the site. During the pre visit; the surveyor should do the following beside walking all over the site

·         • Making a sketch plan of the site in the field to be surveyed

·         • Choose the surveying stations

·         • Marking of the surveying stations by establishing station pegs.

GEOGRAPHY FORM 5- INTRODUCTION TO SURVEYING
Observation and measurement

It is considerably to be the conducted to actual surveying. During this state, the surveyor determines the relative positions and size of the natural and artificial features on the lad surface. There are three forms of measurement required

(a) Liner measurement

(b) Angular measurement

(c) Heights measurement

Liner measurement involve the determination of distance between to one point and another on the surface on the earth. Measurements are done with the use of chain or tapes.

Angular measurements involve the taking of the bearings between stations or from one station to another. Angular measurements are commonly taken with the use of prismatic compass.

Heights (altitudes) are determined with the use of leveling staff and leveling instrument and this particularly determination is made in the conduct of leveling.

 

Presentation (plotting)

It is all about the presentation of the data collected from the field during surveying in the form which allows the information to be clearly interpreted and understood by others. It is done by entering the measurements taken at the field in the field notes. The process is known as booking of field data. Thus booking is the process where by the measurements which are done in a field areas entered in a field note book for recording

Commonly booking is done by surveyor and not by assistant for the sake of avoiding unnecessary errors.

In the process of booking all measurements entered must be in raw units from the bottom up wards. All the linear measurements should appear at the center of the column. Features at the right hand side must be recorded on the right hand side, while those in the left side must be recorded on the left hand side of the column. All offsets must be shown on the relevant side as they appear along the survey line. The forward and backwards bearings must be known and should be circled.

Booking can be by either single line or double line bookings

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