'Satellite Imagery is Critical to Construction'
What is satellite imagery and what are the important applications of that in planning?
Satellite imagery is one very way of remote sensing. The broad word for remote sensing means sensing things and feeling them from a distance. We can think of the human eye as first remote sensing tool. This is where satellite imagery came. Why do we need satellite imagery? If you're doing a planning job for instance, you want to construct a road that connects town A with town B, you want to see the topography, one way is to send your surveyors but if they just go to the site, they will see only what they can with their eyes whereas if it a satellite image taken from top, you will see the whole area and show you how to plan the entire road.
Another major application of satellite imagery is regional planning. For instance we have been involved in the regional planning for the whole of the reverine areas of Delta state. We use satellite imagery to do the land use mapping and the verification of existing topographic maps. Through satellite imagery, we were able to locate mangrove areas in Delta state, the residential areas, existing infrastructure like major roads, urban and non-urban areas and this gave us a comprehensive view of the whole area which was the first step towards our planning. Visiting the site is very important but it will show you just a localised point. The eyes cannot capture more than two or three kilometres but the satellite imagery you can capture and area that 200 square kilometres.
You know that Nigerian has launched her satellite and we tested in our company the use of the NigerianSat1 in updating the topographic maps of Nigeria. The existing topographic maps of Nigeria which dates back to the 60s are almost obsolete now. For example, a topographic map of Warri at that time shows existing road network but when we acquired the satellite image for the city of Warri and we updated the road network and this include the extra roads built in the city from that time. There is a huge amount of data that needs to be updated.
Did you use information from the Nigerian Sat1 to update that?
We used a similar satellite because we did that before Nigeria launched the satellite. We proved that the Nigerian satellite could be used to update these maps.
For example, in Escravos the new map reveal that Nigeria has actually gained land because the area that was water occupied before has inched inwards and that means that Nigeria has gained more land instead of losing it. This is because sedimentation of the River Niger and a lot of sand is being sedimented along that area. Nigeria is gaining land between the 60s and 2002 some quite good portion of land has been gained.
As a matter of fact this happened in all the coastal areas not only in Escravos. Which used Escravos as a case study. There is an immense need for updating these topographic maps and one way of doing that is the traditional aerial photography and surveying technique but this process is really costly in terms of money and time. Updating using the digital technology and the satellite imagery can reduce the cost by far.
What is the actual kilometres of land gained?
I don't have the specific number of kilometres but we can calculate that later. What we did was a demonstration I can not calculate in terms of square meters now.
But there is a difference no doubt. Another example is what we call meandering of rivers. Huge rivers like river Niger and other important rivers in Nigeria keep on changing their path because of the amount of water flow and because of the type of soil. The new imagery shows the old path that river Niger used to take in part of Delta state. It has changed its path tremendously. This is a very important application of satellite imagery in updating the maps. Another consideration is that existing topographic maps are available on paper format but now they are available digitally which means that instead of losing the quality of the information due to weather or water which may affect papers, they are now digitally and it is an important first step. This procedure will keep existing maps from deterioration but this is not enough. After digitising them, there is need also to update them through satellite imagery. You see the data on existing maps was collected over forty years ago. With the satellite image you see the difference, the new things that have occurred. For example satellite imagery will detect new roads, new lands, change in land use especially in areas where desert has encroached. In the north, desert is encroaching and it is moving southwards at a fast rate of about one or two kilometres a year which is amazing because a lot of land has changed from fertile green land to a desert in areas prone to desertification. What we call land use mapping would also be affected. How do we do it? First we go to remote sensing through satellite imagery.
Apart from that what about other environmental problems?
One of the proposals that we did was to acquire and update a series of satellite imagery covering the north. We get these dating back from the seventies and superimposing them on top of each other and seeing how desert is moving. With that we can map and measure desert encroachment. We can determine areas prone to desertification and proposal a plan to combat desertification. Also another application is to use remote sensing to monitor erosion. In the south of the country, erosion is eating most of the land and is creating other paths. Nigeria Sat1 is a satellite which is of great use for specifically environmental application. The way it is configured suits more environmental application that is why it is called a DMC satellite which means Disaster Monitoring, Control satellite.
The satellite use the technology of the lense. The eye need three bands to visualise-the red blue and green colours-but it is more complicated technically than that. Green for example has a certain reflective range, the eye can detect it so are red and blue. The human eye can see all the ranges between the red and the blue. The infra red and ultraviolet bands cannot be seen with the human eye. The Nigerian satellite came with two visible bands and one invisible band which is infrared band. The infrared band can be highly used to detect vegetation so we can use it for agricultural application as well it can be used for disaster control application for example if a big fire happens, the infrared is highly sensitive for temperature and fire. We can use the Nigerian satellite to detect the extent of such fire disaster and how we can immediately remedy the problem. It can also be used to detect flood. If detected and applied to a topographic digital map and we see the contours, we will see how fast the flood will continue and to which areas the topography will stop it and what villages would be affected.
What about the security implications?
Every satellite ca be negatively used but the way the satellite operator operates the satellite is minimising this. Some huge companies use satellite for huge espionage purposes. They inspect the silos of competing companies. For example, if you are a major oil producer, you can acquire an image of another company and see how much oil they have and use your planning to see how you can compete with that but I don't see it as something which is a threat. Its more of creating a healthy competitive environment.
For example, satellite imagery has been used widely to test the crop yield of other areas. If you a country producing wheat and your major customer is a neighbouring country. If that country produces half of its consumption this year and about 90 percent of its consumption next year, with satellite you can plan on how you can produce in advance to sell to the other country. I can take a satellite imagery of your farm and through the infrared band and my remote sensing capabilities, I can detect your yield, estimate your consumption, see the difference and plan. This is a way it can be used for healthy competition and to assist in planning. That does not mean that it cannot be used for insecure operations. It is the job of the imagery providers not to sell satellite imagery to non-customers and for a non-application. For example, if you want a satellite image, you have to specify that you need the image for a specific job. If I want to go to Nigeria National Space Agency, I will tell them that I need to do for example, land use mapping for say Kano state. They will approve giving me the satellite image.
Lets assume that we are in competition say in the oil sector and I suspect that you are spying on my installations. Is there anything I can do to prevent you from succeeding?
Yes. Just cover your tank!
Just that? With what?
With either concrete or aluminium or whatever. The satellite image is an eye. If you block the thing, you can simply block anybody from seeing it. I cannot through satellite see you in this office because there is a wall between us and the sky. So this is why I said that it is a safe process in as much as you are not using it for defence or intelligence. Oil companies can do something to protect their interest.
Our company has been involved in a variety of consultancy jobs in Nigeria and we have been trying since we came in 2000 to introduce the technology of satellite imagery to Nigeria. We are among the first people to use satellite imagery in road designs at the Federal Ministry of Works and we have used it on Onitsha-Owerri road and another in a bridge linking Asaba road. That area was a 400 meters bridge in a mangrove area so we used satellite imagery for the bridge the most optimum way. In addition to road
design, we have finished the regional plan for reverine area of Delta State. This is a major project because it involves plans for settlement, road networks, transportation planning, water drainage, waste management, telecommunication, health, education, industry. We have all these sectors of the riverine areas of Delta state and came up with a ten-year plan for the state for the best development of that region. And we came up with a master plan that states how Delta state can utilise its resources in all those sectors to best develop that region.
Other projects include the waste management plan for the city of Port Harcourt. We have designed for them a comprehensive and integrated waste management plan facility comprising a land cell, a compose plan, a waste disposal facility and this will be a first step towards a complete design and implementation of this important waste management plan and this was under the Federal Ministry of Environment. With the Nigerian Space Agency, we are currently developing a computer software that makes uses of the two visual bands of the Nigerian satellite plus the near infrared band and create a true colour composite so that you can see what the satellite transmits as if it were your eyes.
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