ELEMENTARY SURVEY

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 GEOGRAPHY FORM FIVE TOPIC FOUR NOTES SURVEY  

SURVEY SIMPLE SURVEY AND MAP MAKING INTRODUCTION TO 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 5.1 

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 to 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 

- Cadastral 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 

 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. 

 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 ·  

1. Chain survey 

2.  Plane table survey 

 3. Prismatic survey 

4.  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 

1. Reconnaissance survey 

2. Observation and measurement ·  

3. Presentation or plotting of the data  

1. 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. 

 2. 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. 

 3. 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 

 CHAIN AND TAPE MEASURE SURVEY 

Chain and tape survey is a science of measuring series of straight lines on the ground with the use of a chain or tape measure. It is the simplest and commonest method of making linear or horizontal measurements on land particularly for the smaller distances. 

 Significant uses of chain survey 

• Chain survey is conducted to develop details which can be used for mapping areas. 

 •Chain survey is conducted to develop details for construction purposes. 

 •Chain survey is conducted to collect data to be added to the existing data. 

 •Chain survey is conducted to supplement other topographical survey techniques like plane table survey and prismatic compass survey. 

Tools used in the conducting chain survey 

 The main tools used into the conducting chain survey include the following:- 

 i. The chain:- It is a tempered steel wire with length of about 20m or 30 m. It has links connected by small rings in such a way it can be easily folded and carried in the field. The length from ring centre to another is of about 200 mm. It is used to measure distance on the ground along the line of tracery. 

ii. Tapes 

 (a) Those which made up of steel and available in varied length up to 100m 

 (b) Those make up of fiberglass and they are available in lengths of 10m, 15m, 20m, and 30m Tapes like chain, are also used for liner measurements particularly of short distances.  

iii. Cross staff They are made of metal or wood with eye slits at right angles. They are used to measure right angles of the off sets from the line of traverse.  

iv. Ranging rods /poles They are poles of woods or light metal 2m, 2.5 or 3m long. They are painted alternatively in red and white bans each 500 mm long so that they can be easily seen from a distance. They have pointed metal ends for driving into ground. They are used to mark points required to be seen in linear measurement 

 v. Arrows These are steel skewers of about 0.4m long. They are used for marking points an ground when chaining a long (line) distance, They are potentially used when the chain has to be laid down several times and the positions of the end of chain are marked with the arrows. 

vi. pegs They are wooden station marks with 40mm square and 50 cm long. They are driven into the ground to mark positions permanently during survey. 

 vii. Optical square It is optical instrument of camera like for setting out angles. It is commonly used for marking off sets at right angles from the line of traverse. 

viii. Prismatic compass It is a compass box with needle in the magnetic liquid to enable the needle to swing freely at the centre. There is a card which is graduated in the degrees to enable the reader or the viewer to read the given bearing or observed bearing. 

 ix. Field sheet/Note book They are writing sheets They are used for recording or booking all necessary field work information 

FIELD WORK OF A CHAIN SURVEY (METHOD OF CHAIN SURVEYING) 

 The conduct of chain survey in the field area 

 1. Preliminary inspection of the field area The site whose details to be taken by conducting chain survey should be pre visited. This is commonly known as reconnaissance survey. During the pre visit, the surveyor work all over the site to obtain a picture in his or her mind of the whole area. More over, 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 with leader. 

 2. Organization of chain survey team It should have three people including the leader, follower and booker 

 The leader has a role of reading measurements taken in the field with the use of chain. He also pulls the chain forwards and insert the arrows at every point or station 

 The booker has a work of recording data as given from eh leader ·  

The follower has a role of organizing the instruments during the field work. He also directs the leader where to insert the arrow and collect them. · 

Note: The main chain survey work has to start as follows 

 (a) The chain is thrown and extended from one position to another and disentangle knots 

 (b) Leader takes arrows and ranging road, and follower takes ranging rod 

 (c) Follower erects road at first base point places brass handle of the chain against rod. In this leader ex tends the chain follower by the follower 

 (d) Leader straightens the chain and inserts arrow at end of brass handle. Offsets, liner distances and the point can be taken 

 (e) The leader drags chain so that follower is on a leader is arrow. Then follower moves to the leader arrow and places pole behind arrow. The process of dragging the chain, signing and aligning is repeated until the line is completed the same process is also repeated with another lines until the whole area is surveyed.  correct signals as seen by surveyor leader.. 

 OBTACLES IN CHAIN SURVEY 

Those are the features (object) lying with in the area to be surveyed along the survey line which may hinder or prevent chaining or ranging. Types of obstruction 

There are three types of obstruction in chain survey · 

(a) Those which do not allow crossing from side to side, river, a lake, pond preventing chaining. 

 (b) Those which will prevent vision but not chaining e.g a hill 

 (c) Those which prevent both chaining and vision e.g building. 


 TECHNIQUES (WAYS) TO OVERCOME THE OBSTACLES 

 There are seven ways on how to overcome the obstacles. The methods depend on the nature of obstacles as follow 

 1. HILL Hill is a rounded upland it is a considerable obstacle if lies on the path of the chain line. The obstacle of hill can be avoided by the following consideration techniques. 


MEET ME IN THE NEXT LESSON ON WEDNESDAY....................................

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