More heavy rains, floodwaters coming, may last 12 weeks, govt agency warns

By Gabriel Ewepu

The Director General and Chief Executive Officer, Nigeria Hydrological Services Agency, NiHSA, Umar Mohammed, says last week’s devastating floods in Lagos State and some other states across the country were not a surprise.

The DG added that NiHSA’s forecasts and warnings were disregarded.

According to him, before the floods, NiSHA had performed its forecasting using several models, saying, “This is something we foresaw, we saw it coming.”

He warned, “As we speak now, with the flooding happening, if nothing is done, this is just the start of the rainy season, sometime around July-September (12 weeks), and it could be worse than what is even happening right now.  

“And we’re expecting it to be worse around August-September, particularly August-September”.

Muhammad also raised fears about how the flooding could affect drinking water in affected states as it could be polluted.

On Tuesday, torrential rainfall in Lagos had lasted over 12 hours submerging property and roads in Lagos while bringing commercial activities and vehicular movement to a halt.

The downpour, which started on Sunday, reached a crescendo, leaving motorists and commuters stranded across the metropolis, while residents had to bail out storm water from their homes to stay safe.

Parents and guardians, in panic mode, prevented their children and wards from going to school due to  severity of the downpour and possible risks.

The areas heavily flooded include Lagos-Oshodi Expressway, Abeokuta Expressway, by Oshodi bus stop, Lekki-Epe Expressway and environs, Victoria Island, Agege, Ikeja, Oworonsoki, Gbagada, Funsho Williams Avenue, formerly called Western Avenue, Iwaya area of Yaba, Lagos Mainland Local Government Area, and other coastal areas.

However, viral videos online monitored showed residents and motorists stuck in floods, sending SOS message to the state government for intervention.

The NiHSA DG argued, “Lagos is a coastal state, and so it has lots of factors that can influence flooding within the state, peculiar to Lagos.

“Lagos is a very large urban city, and then it also has a very large river that cuts through the city, and then it is just by the ocean. So, with this, all the three major forms of flooding, particularly in Nigeria, can happen in Lagos.

“Urban flooding can happen in Lagos, riverine flooding can happen in Lagos, and even coastal or tidal flooding can happen in Lagos.

“So, imagine situations where there is urban flooding, and then the river rises. “There is going to be a collision of types of flooding that can even be more devastating.

“And with the nature and terrain of Lagos, I wouldn’t want to say flat, Lagos is at some point below sea level.

“When I say below sea level, there is a sea level, and usually ground is supposed to be above the sea, and that is why the ground is not submerged underwater”.

Mohammed spoke to Sunday Vanguard through the Head, Geographic Information System, GIS, and Remote Sensing, Emmanuel David Tuna, at the weekend.

“From the point of the bank or the beach area, it is above sea level. Now, some sections, particularly in Ikoyi, that I have been to, where we use some of our devices and our GPS to check the altitude of the ground, we got to see that some areas in Lagos are point zero, meaning equal level with the sea.

“Some places are even below the level of the sea. But not all parts of Lagos, there are some parts of Lagos that are above, and these areas that we get to witness flooding a lot of times in the urban region are below sea level.

“And we ask lots of questions. We ask the behavioral pattern of this flooding because sometimes when this floodwater happens, we may not be there to see the actions, but we know from experience how floodwater ought to behave, and then we ask questions – does it come in a certain direction?

“Does it come with speed? Velocity? Is it stagnant?

“During the peak of the rainy season, are these waters more stagnant than flowing? Or in certain areas, do they flow? When they flow, what direction do they take?

“Do they flow from point A to point B or B to point A?

“From our analysis, we know where it is flooding but with eyewitnesses, it’s more like it validates what we have, and when I mentioned that we are not surprised, it’s because we noticed that these areas that are below sea level are already, as of the time we went there, which is after the rainy season, sometime between October and November, most of their drainages already were filled with water and stagnant.

“Number one, drainages filled with water, sometimes even to the brim, and there was no flooding, drainages were already filled.

“Secondly, these drainages, we noticed that as they were filled, were not flowing.

“So there’s a blockage somewhere.

“Now, apart from the blockage, these drainages are also silted up with dirt and other debris-sand and plastics and all of that.

“So you would get to notice that it forms more like a pond system.

“Instead of it flowing out of the town, several areas will flow into the town and make it stagnant, and lots of flooding in Lagos, we were expecting it to be more stagnant as it is flowing from what we are seeing, from reports we are seeing.”

 ‘Ogun River flowing into Lagos’

“So, now that it is flowing, there is every indication that the river is also contributing. “So, now there is urban flooding at stake, currently happening, and riverine flooding combining with it.

“Riverine flooding is not supposed to be a factor in this area but it is because the urban flooding has already started and filled up all areas the rivers were supposed to flow to.

“So, the river was just coming into urban flooding, now intensifying the situation.

“It’s a freshwater river and comes from the Ogun River itself. Ogun River coming into Lagos, it didn’t just flow directly into the ocean.

“It divides, creates more like a small tributary within the state.

“And we expect many things like this around the coastal area.

“When a river is trying to flow down into the ocean, it divides and breaks, either forming a small delta or having some tributaries that flow to the ocean.

“So these tributaries flow into urban flooding and increase the intensity.

“So, without this river, it would have just been urban flooding and stagnant.

“But this flow coming into urban flooding intensifies this, and at this stage, we should be fortunate enough that the tides are not even high to combine with this; if not, it will have nowhere to flow to, and the area that is being submerged will be way higher.

“So peculiar to Lagos, the three types of flooding can happen in Lagos. And when they happen simultaneously, it becomes a challenge.”

‘Dangerous flooding’

 He warned, “As we speak now, with the flooding happening, if nothing is done, this is just the start of the rainy season, sometime around July-September, and it could be worse than what is even happening right now.  

“And we’re expecting it to be worse around August-September, particularly August-September.

“The reason is, as we speak, the ground is already saturated, Lagos is flooding, and it is extending this long because it has nowhere to go to.

“Remember I said some areas are below sea level. So it can’t even flow out of the town. “The ground has to absorb this flood water, or even push it out.

“So, if it is not doing that, the ground would be forced to absorb this water, and it would take longer time for the flood water to even escape.

“And if it does not escape enough, and more rain comes in, flooding may extend to days, possibly even a week or two”.

‘Predictions, warnings disregarded’

 The DG also said NiHSA’s earlier predictions and warnings were disregarded and discarded because “we saw this coming, it was a challenge, and we actually spoke out through the media about some of the conditions that were happening in Lagos.

‘Concerns about drinking water’

 “So, apart from flooding, there was something else we were also concerned about drinking water, the quality of the water because we knew that this flooding was coming, we were not certain of the intensity of the flood, but we knew it was coming.

“We were concerned about the drinking water because we expected it to last longer, the flood to last over a long period.

“And then we were concerned about the drinking water across states.

“So, we started analysing the quality of the water, and we did, we have our reports.

“So, we wanted to observe the quality of the water before the flood because we know that after flooding, or even during flood, we are expecting challenges of drinking water in the states.

“And then we are trying to compare, before flood, what is the quality of the water in boreholes, the water that the community and residents drink. Then after flooding, what is the condition of the water?

“So we can get to confirm what is polluting the water. We want to confirm the sources, particularly the source. So we have before flood records, as we speak, and now that flooding is happening, I am sure my DG is already putting together a team to go to Lagos and get a post-flood report.”

‘Flood to recede 

in October’

 However, the NiHSA boss said the floods in Lagos will recede in October but not before going into on-and-off pattern.

“We are expecting the floods to recede sometime, at this stage. We are expecting it within days but to also kick-start again, it’s going to be an on-and-off period of flooding. “We are expecting this flood to be on and off, and to span from July to September on and off.

“Around October, we are expecting these rains to be receding, we still expect flooding, but the intensity may not be as high but we are still expecting flooding in October, and the only time we can be safe, I will be honest, is possibly around November.

“In October, we are expecting low flood, and we have reports and weekly forecasts that we are currently issuing out today and for the rest of the year, analyzing these events but particularly not to Lagos alone, for the entire country but as we are speaking about Lagos, we also have analysis about Lagos to show the extent of our forecasts because we are not expecting it to stop now. “There are some areas that have never experienced flooding in Lagos before until this year.”

Poor cooperation

The DG lamented poor cooperation from state governments on annual flood predictions and what to do to mitigate the impact as he said, “We have a challenge of cooperation from states, a serious challenge with cooperation from states. Most times we come before flood starts because we are not coming when the flood is happening, they are not seeing any impending danger. Most times we get disregarded. Our warnings are not taken with seriousness.”