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NIHSA FLOOD & DROUGHT MONITOR


1.0 TRANSBOUNDARY BLACK FLOOD RISING IN NIGERIA

The Transboundary Black Flood flow of River Niger from Guinea is still rising in Nigeria at Jiderebode, Kebbi State, upstream Kainji Dam in January 2020 and expected to attain its peak flow in February or March 2020. The flood has a maximum Water Level (WL) of 3.45m corresponding to a discharge of 1,790 m3/s recorded on the 31st January 2020. The minimum WL was 341cm corresponding to a discharge of 1,758 m3/s recorded on 1st January 2020 while the mean WL for the month was 343cm with the discharge of 1,779 m3/s as shown in Fig.1.

The Black Flood is having no negative impact downstream of the country because of its absorption by the Kainji and Jebba dams and also serves as a source of recharging those dams during the dry season.

The riparian communities are strongly advised to take precaution to avoid flood disasters in the flood prone areas.


Fig.1: Comparative Hydrograph of River Niger at Jiderebode Upstream Kainji Dam.

2.0   BLACK FLOOD NOW RECEDING IN NIAMEY, NIGER REPUBLIC

The Transboundary Black Flood flow of River Niger coming from Guinea, is receding in January 2020 after attaining a maximum WL of 556cm corresponding to discharge of 1,915 m3/s on the 17th January 2020, in Niamey, Niger Republic, upstream of Nigeria as shown in Fig.2,.

The River Niger Black Flood occurs in the dry season while the White Flood in the rainy season.

The riparian communities are also strongly advised to take precaution to avoid flood disasters in the flood prone areas.

Fig.2: Hydrograph of Receding Black Flood in Niamey, Niger Republic.

3.0 RIVER NIGER FLOW SITUATION AT LOKOJA

The flow of River Niger at Lokoja (Kogi State), confluence of Rivers Niger and Benue, is decreasing with a maximum WL of 365cm corresponding to a discharge of about 4,284 m3/s recorded on 1st January 2020. The minimum was 319cm corresponding to a discharge of 3,284 m3/s recorded on 31st January 2020 with a mean WL of 334cm corresponding to a discharge of 3,560 m3/s.

The 2019/2020 Comparative Hydrographs of River Niger at Lokoja with that of 2018/2019 and 2012/2013 hydrological years is shown in Fig 3.

Fig. 3: Comparative Hydrographs of rivers Niger and Benue at Lokoja.

4.0  FEBRUARY 2020 CLIMATIC FORECAST IN NIGERIA

4.1 Mean Monthly River Flow Forecast

The Mean Monthly River Flow Forecast in Nigeria in February 2020 will range from 1,000 m3/s to 5000 m3/s along River Niger and from 1 to 5 m3/s in the hinterland while it will be from 5 to 10 m3/s in the coastal areas of the country as shown in Fig.5.

Fig. 5: Mean Monthly River Flow Forecast in February 2020. (sources: www.climateservice-global.eu)

4.2  Mean Monthly Temperature Forecast

The Mean Monthly Temperature Forecast in February 2020 in the country will range between 15oC to 20oC in the North and above 25oC in the South as shown in Fig. 6.

Fig. 6: Monthly Mean Precipitation Forecast In February 2020 (sources: www.climateservice-global.eu)

4.3  Actual Evapotranspiration Forecast

The Actual Evapotranspiration rate forecast in February 2020 will range from 0 to 1 mm/day in most parts of the country except the coastal areas where it will be between 2 to 3 mm/day as shown in Fig. 7.

Fig. 7: Mean Monthly Actual Evapotranspiration Forecast in February 2020 (sources: www.climateservice-global.eu)

4.4 Potential Evapotranspiration Forecast

The Potential Evapotranspiration rate forecast in February 2020 will range from 5 to 6 mm/day in the extreme North, 7 to 8 mm/day in other parts of the country and 4 to 5 mm/day the coastal areas as shown in Fig. 8.

Fig. 7: February 2020 Mean Monthly Potential Evapotranspiration Forecast

4.5 Mean Monthly Soil Water Content Forecast 

The mean monthly Soil Water Content in February 2020 will range from 0 to 0.1 mm/day in the North and from 0.2 to 0.5 mm/day in other parts of the country as shown in Fig. 8.

Fig. 7: February 2020 Mean Monthly Potential Evapotranspiration Forecast

REFERENCES

  1.  Hydrological Data from NIHSA Gauge Stations
  2. www.sath.abn.ne .
  3. www.fanfar.eu
  4. www.platform.princetonclimate.com
  5. www.climateservice-global.eu


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River Niger Water Level Decreasing


The flood Water Level (WL) at Lokoja (Kogi State), confluence of Rivers Niger and Benue has been decreasing after attaining a maximum WL of 10.60m corresponding to a discharge of about 23,647 m3/s on 22nd September 2019 and a minimum of 3.44m corresponding to a discharge of 3,724 m3/s on 4th June, 2019 as well as a mean WL of 6.72m corresponding to a discharge of 11,061 m3/s.



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Lokoja Flood Water Level in Red Alert


In August 2019, the Flood Water Level (WL) at Lokoja (Kogi State), confluence of Rivers Niger and Benue has reached the zone of Red Alert with a maximum WL of 8.24m corresponding to a discharge of about 15,716 m3/s on 31st August, 2019 and a minimum of 6.67m corresponding to a discharge of 10,929 m3/s on the 1st August, 2019 as well as a mean WL of 7.23m corresponding to discharge of 12,513 m3/s.

Even though, the Comparative Hydrographs of River Niger at Lokoja in 2019/2020 compared with those of 2018/2019 and 2012/2013 hydrological years showed a lower WL in the zone of Red Alert, the flood flow tendency will continue to increase this September 2019 (Fig.1).  

Warning: The Riparian Populace are strongly advised to move out of the flood-prone areas to avoid flood disasters resulting from increasing flash floods and transboundary river flows.