What is levelling?

In the context of surveying and construction, leveling refers to the process of determining the height or elevation of points on the Earth’s surface relative to a reference point or benchmark. It is a technique used to establish and measure height differences, slopes, and contours of the land.

The leveling process involves the use of a leveling instrument, typically a level or a theodolite, along with a leveling rod or staff. Here is a general overview of how leveling is performed:

  1. Setting up the Instrument: The leveling instrument is set up on a stable tripod at a known reference point or benchmark. This point has a known elevation, usually determined through previous surveying work or government-provided benchmarks.
  2. Establishing a Sightline: The leveling instrument is adjusted and leveled so that it is perfectly horizontal. A sightline is then established by aligning the crosshairs of the instrument with a specific point on the leveling rod held at the reference point.
  3. Moving to Target Points: The leveling rod is then moved to the desired points where the elevation needs to be determined. The person holding the rod ensures it is held vertically and the instrument is focused on the rod.
  4. Reading the Elevations: The instrument’s crosshairs are aligned with the point on the rod, and the instrument’s leveling staff or a digital readout displays the difference in height between the reference point and the target point. This difference is known as the vertical distance or the height of collimation.
  5. Recording the Data: The elevations or height differences are recorded in a field book or digitally for further analysis and documentation.

By repeating this process at various points across a survey area, leveling allows for the creation of accurate topographic maps, determination of slopes and grades, and establishment of reference points for construction projects. It is an essential technique in civil engineering, construction, and land surveying for ensuring precise and reliable measurements of elevation.

Dangers of over depending on the exportation of agricultural products and their solutions

The following are the dangers of over depending on the exportation of agricultural products

  • Price fluctuations on the world market cause unstable export earnings, hence reducing government earnings.
  • Agricultural products fetch low prices on the world market, which discourages farmers from growing crops for export.
  • Losses because of poor storage facilities, which reduce on the quality and quantity for export.

  • Agricultural products are seasonal and therefore can’t be relied on for a constant supply for export.
  • Most farmers are reluctant or have inadequate capital to adopt modern agricultural methods for export production.
  • Most agricultural areas are inaccessible which limits quick delivery for exportation.
Dangers of over depending on the exportation of agricultural products
  • Agricultural products are prone to climatic hazards e.g. hailstorms and long drought cause fluctuation of products for export.
  • Pests attack the crops leading to a reduction in quantity for export which reduces foreign exchange earnings.

  • Disease outbreaks also attack the crops leading to poor quality output which reduces market demand.
  • They are perishable and therefore require air transport which is expensive to transport to foreign markets for export.
  • Agricultural products are bulky and therefore difficult to handle for export.

Steps taken to solve the problems of overdependence on agricultural products for exportation

  • Widening the export market base by investing in market research and creation of new trade partners.
  • Reviving co-operative societies to improve on marketing of agricultural products for export.
  • Encouraging scientific research to improve on the quality and quantity of agricultural exports.
  • Improving handling and packaging of perishable agricultural export crops through reviving marketing boards and co-operatives.
  • Using pesticides and herbicides to control pests and diseases to improve on quality and quantity of export crops
Steps taken to solve the problems of overdependence on agricultural products for exportation
  • Encouraging the government to promote economic diversification to offer an alternative to the agro-based economy.
  • Liberalization of the economy to encourage private investment in the economy to foster economic development.

  • Diversification of the export sector and encourage exportation of other commodities e.g. timber, fish and minerals.
  • Developing export promotion industries to export manufactured goods with high market demand.
  • Promotion of tourism as an invisible export to bring in more foreign exchange for national development.
  • Promotion of exportation of services e.g. banking, transport, labour, education to widen tax base for government.
  • Educating and sensitizing the masses about the dangers of over-reliance on agriculture and offer alternatives for survival.
  • Exporting art and craft products to offer an alternative export item.
Steps taken to solve the problems of overdependence on agricultural products for exportation



Surveying or land surveying is the art of and science of determining the relative position of various points or stations on the surface of the earth by measuring the horizontal and the vertical distances, angles and taking the details of these points, and by preparing a map or plan to any suitable scale.

In other words, surveying is defined as taking a general view of, by observation and measurement determining the boundaries, size, position, quantity, condition, value, etc. of land, estates, building, farms mines etc. and finally presenting the survey data in a suitable form.

This covers the work of the valuation surveyor, the quantity surveyor, the building surveyor, the mining surveyor, and so forth, as well as the land surveyor

definition of land surveying

Another school of thought defines surveying …as the act of making measurement of the relative position of natural and manmade features on earth’s surface and the presentation of this information either graphically or numerically

3 stages of process of surveying

Taking a general view

This part of the definition is important as it indicates the need to obtain an overall picture of what is required before any type of survey work is undertaken.

In land surveying, this is achieved during the reconnaissance study.

Observation and Measurement

This part of the definition denotes the next stage of any survey, which in land surveying constitutes the measurement to determine the relative position and sizes of natural and artificial features on the land.

Presentation of Data

The data collected in any survey must be presented in a form that allows the information to be clearly interpreted and understood by others.

This presentation may take the form of a written report, bills of quantities, datasheets, drawings, and land surveying maps and plans showing the features on the land.


Surveying is made up of various specializations known as sectors or classes as shown below:

General Practice Surveyors:

Surveyors under this class are mostly concerned with valuation and investment.

Valuation surveyors deal with property markets, land and property values, valuation procedures, and property law.

Investment surveyors help investors to get the best possible return from the property.

They handle a selection of properties for purchase or sale by pension funds, insurance companies, charities, and other major investors.

They also specialize in housing policy advice, housing development, and management.

Planning and Development Surveyors

They are concerned with preparing planning applications and negotiating with local authorities planners to obtain planning permission.

Building Surveyors

Their work involves advising on the construction, maintenance, repair of all types of residential and commercial property.

The analysis of building defects is an important part of a building surveyor’s discipline.

The Quantity Surveyors

They evaluate project costs and advice on alternative proposals.

They also ensure that each element of a project agrees with the cost plan allowance and that the overall project remains within budget.

Rural Practice Surveyors

Surveyors in rural practice advise landowners, farmers, and others with interests in the countryside.

They are responsible for the management of country estates and farms, the planning and execution of development schemes for agriculture, forestation, recreation, sales of properties, and livestock.

Mineral Surveyors

They plan the development and future of mineral workings.

They work with local authorities and the landowners on planning applications and appeals, mining laws and working rights, mining subsidence and damage, the environmental effects of land and deep underground mines.


Leveling is a method or element of land surveying which deals with determining points on land surface above sea level.

The points of known height are called benchmarks and they are determined from an assumed zero height point at sea level called a datum.

It employs leveling instruments such as theodolite and the Abney level. 

The following are the importance of leveling in field work:

1. It helps the surveyor or cartographer to make contour maps of the land sea surface.

A contour map is a map that shows the elevation of the land surface. It is created by connecting points of equal elevation with lines. Leveling is used to determine the elevation of these points. The surveyor or cartographer first establishes a benchmark, which is a point of known elevation. They then use a leveling instrument to measure the elevation of other points relative to the benchmark. These measurements are then used to create the contour map.

Contour maps are used for a variety of purposes, including:

  • Planning construction projects
  • Designing drainage systems
  • Predicting flooding
  • Understanding the effects of climate change

2. It helps pipe transport engineers to ensure appropriate slope of the land that will allow smooth movement of the liquid in the transit e.g water and liquid.

When transporting liquids through pipes, it is important to ensure that the pipes are sloped properly. This ensures that the liquid flows smoothly and does not pool or back up. Leveling is used to determine the slope of the land and to design the pipe system accordingly.

The slope of the pipe is determined by the elevation of the inlet and outlet points. The surveyor or engineer will use a leveling instrument to measure the elevation of these points. The difference in elevation between the two points is then divided by the length of the pipe to determine the slope.

The slope of the pipe must be sufficient to allow the liquid to flow without backing up, but it must not be too steep, as this can cause erosion. The appropriate slope will vary depending on the type of liquid being transported and the diameter of the pipe.

3. It helps contractors to lay a level ground on which they can elect the building.

When building a structure, it is important to ensure that the ground is level. This is because a level foundation is essential for a stable structure. Leveling is used to determine the elevation of the ground and to create a level surface for the foundation.

The surveyor or engineer will use a leveling instrument to measure the elevation of the ground at various points. They will then use this information to create a plan for leveling the ground. The ground is leveled by removing or adding soil until it is level.

4. It is also important in the construction of routes of transport like roads and railways.

When constructing roads and railways, it is important to ensure that the surface is level. This is because a level surface provides a smoother ride for vehicles and reduces the risk of accidents. Leveling is used to determine the elevation of the ground and to create a level surface for the road or railway.

The surveyor or engineer will use a leveling instrument to measure the elevation of the ground at various points. They will then use this information to create a plan for leveling the ground. The ground is leveled by removing or adding soil until it is level.

In addition to these four, leveling is also used in a variety of other applications, such as:

  • Site development
  • Land surveying
  • Civil engineering
  • Mining
  • Agriculture
  • Forestry

Leveling is a valuable tool that is used in a wide variety of fields. It is essential for ensuring the accuracy of measurements and the safety of structures and infrastructure.



Air transport is a mode of transportation that involves the transportation of goods and passengers by the use of airplanes, helicopters, and other types of aircraft. Air transport is the most recent mode of transport. It is the gift of the 20th century to the world. 

The two world wars gave a great impetus to the development of air transport in almost all the countries of the world. The peculiar characteristic of air transport is that it does not need a specific surface track for its operations.

It has no physical barriers as in the case of other modes of transport. Political boundaries are also immaterial, although it has to observe the requirements of International Law. The supreme advantage of air transport lies in its quickness.

It is the fastest mode of transport. But the cost of its operation is very high and thus it is suitable for only rich passengers, mails and light and costly cargo. However, in advanced countries like the U.S.A., Germany, etc. it offers tough competition to the railways.

7 advantages of air transport


High Speed

It is the fastest means of transport. Passengers and goods can be transported easily from one place to the other.

Minimum Cost

Unlike railways and road transport, there is no need to spend money on the construction of any track or road, only airports have to be constructed.

Strategic Importance

An airway has great strategic importance. It can be used for internal and external security.

Easy transport of costly and light goods

It is quite convenient to send costly, light, and perishable goods through air transport.

Free from physical barriers

Air transport is free from physical barriers like rivers, mountains, and valleys, etc.

Useful for Agriculture

Air transport is useful for aerial spray on pests and insects which cause harm to crops.

Useful in natural calamities

During earthquakes, floods, accidents, and famine, air transport is used for rescue operations.


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