Boats Makoko, Lagos and flooding in Nigeria, October 13, 2012
Boats Makoko, Lagos and flooding in Nigeria, October 13, 2012

Utilisation of remote sensing data and GIS for flood disaster management in Nigeria

The slow but gradual and steady change in climatic conditions resulting to global warming is increasingly posing a great threat to the environment and existence of man on earth. This phenomenon is partly attributed to the recurring flood disasters experienced in the flood prone areas around the world.

Nigeria is not an exception as it has been grossly affected by recurring flood disasters in recent years. In 2012, Nigeria experienced one of the worst flood disasters in its history. According to the Nigeria Post-Disaster Needs Assessment (PDNA): “The 2012 floods killed 363 people, 5,851 injured, 3,891,314 affected and 387,153 displaced (Global Facility for Disaster Reduction and Recovery, June 2013).”

Floods in Nigeria (NASA, 2012)
Floods in Nigeria (NASA, 2012)
Comparison with the same area in 2008
Comparison with the same area in 2008Comparison with the same area in 2008

 

Even though the occurrence of flood disasters is unstoppable, appropriate mechanisms can be put in place to check and mitigate the extent of the potential destruction it could cause to the environment. The application of space-based technology involving remote sensing and Geographic Information System (GIS) have been very effective in the management of flood disasters through the gathering and presentation of accurate data and information.

In an interview with a space scientist, Dr. Ezekiel Eguaroje (2018) of the National Centre for Remote Sensing, Jos, Nigeria said: “Remote sensing and GIS are key in the management of flood disasters everywhere in the world. That is one of the reasons Nigeria launched NigComSat-1 in 2003 and NigeriaSat-2/Nigeria Sat-X in 2011.

“Satellite is a space-based technology embedded with high resolution sensors with the capacities to capture images from the earth surface and store them in the form of data as it moves along its path. The NigeriaSat2, for instance, has a high-resolution sensor with the capacity to capture images as small as 22 metres in length from the earth surface and covering an area of 400 square kilometres. The capturing of data by satellite is referred to remote sensing while the interpretation of data to get useful information is referred to GIS (Eguaroje, 2018).”

Furthermore, Dr. Eguaroje explicitly explained: “As the satellites traverse the space 24/7, they are constantly imaging water levels in various water bodies and recording weather conditions. These images are downloaded and interpreted to show the frequency of the changes in water levels (Eguaroje, 2018).”

He explained further that “If there is any sign of flood as a result of excessive rainfall within a given period, in Nigeria for instance, the data will show it. Therefore, the people living around the water channels in the affected areas are notified by the relevant agencies such as National Emergency Management Agency (NEMA) and National Meteorological Services Agency (NIMET) to relocate to safer areas for safety (Eguaroje, 2018).

Nonetheless, space technology isn’t only beneficial for flood disaster preparedness, but also for responsiveness during the flood, and the mitigation of the extent of damage. Furthermore, space technologies can be used to take stock of the destruction.

Eguaroje (2018), added: “When eventually the floods occur, the information obtained from remote sensing data guide NEMA on how to respond to the emergency situation at hand. It equally helps them to keep citizens and government abreast of their rescue effort.”

He pointed out that “After the flood, the data also give them detailed information of the extent of damage caused to the environment (Eguaroje, 2018).”

With the remote sensing data, NIMET is able to determine the trend in rainfall over a given number of years and use such information to forecast the weather and amount of rainfall to be expected during a given rainy season.

So, whenever there would be a possible flood disaster during a given rainy season, NIMET usually announces it to alert the citizens. At the same time those living around the affected areas are warned to prepare for it.

Interestingly, as relevant as remote sensing and GIS are in mitigating flood disasters, most Nigerians are often trapped by floods whenever they occur. Improved response strategy and reaching out to victims of flood disasters in a timely manner is therefore needed

However, Dr. Eguaroje said: “The government has been proactive in responding to impending flood disasters by giving early warning signs and asking people in the affected areas to move to safer areas.

“But often times, the people deliberately refused to heed to [sic.] such instructions until when [sic.] the floods eventually occur and get them trapped” (Eguaroje, 2018).

 

Sources

Post-Disaster Needs Assessment (PDNA): Global Facility for Disaster Reduction and Recovery, GFDRR, 2018

Dr. Eguaroje Ezekiel, personal communication, October 8, 2018

Dr. Eguaroje Ezekiel is a National Coordinator
Cooperative Information Network
National Centre for Remote Sensing
Jos, Nigeria