SUMMARY OF THE HYDROLOGICAL SITUATION

The decrease in flow has continued in the entire part of the river Niger during the month of February. The monthly average flow recorded at the reference stations of 4 catchments area of the basin are: 218m3/s at Koulikoro in the Upper Niger, 1184 m3/s at Diré in the Inland Delta, 1583m3/s at Niamey in the Middle Niger and 2350m3/s at Lokoja in the Lower Niger. Statistical, these values correspond to the 3 year wet return period at Diré, Niamey and Lokoja, while it was 5years return
period at Koulikoro. The total volume recorded from June, 2012 to February, 2013 at these same stations are estimated to be 34.59km3 at Koulikoro, 30.95km3 at Diré, 31.63km3 in Niamey and 250km3 at Lokoja.
Regarding into Dams, the releases of Selingue dam continue to support the Low flow while at the Kainji dam the reservoir storage is close to its maximum capacity.

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During the month of April 2012, the Niger River flows have continued to decline despite some localized rainfall registered in some parts of the basin particularly in the Middle Niger basin. The average monthly flow (157 m3/s) recorded in Niamey was close to the values observed in April once every three years, in dry years in the area. By contrast to Koulikoro in the Upper Niger, the average monthly flow (150 m3/s) recorded was close to the twenty year wet return period. It should be recalled that in March 2012, the difference between Koulikoro and Niamey was that low flows were supported in the Upper Niger by the water releases from Selingue Dam, which effects has very little in the Middle Niger downstream.

This fact is confirmed by the cumulative volume of flow registered from 1st June 2011 to 30th April 2012. These values are 27.84 km3 in Koulikoro which was less than the five-year dry, as against 25.43 km3 in Niamey which is slightly below the average flow volume of the inter-annual mean for that station.

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Low flows continued in March 2012 in all parts of the Niger Basin which is expected to be at the lowest in May 2012. The average monthly flow recorded at Koulikoro in the Upper Niger was 230 m3/s which was higher than twenty years wet flow return period. It was 284 m3/s which was less than the five-year dry return period, in Niamey, in Middle Niger. This difference between Koulikoro and Niamey is that low flows are supported in the Upper Niger by the water releases from Selingue dam, which has little effect in the middle Niger.

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The total flow volume recorded from June 2011 to February 2012 along the river Niger during the 2011/2012 hydrological year is lower than those total flow recorded during the same period in the previous hydrological year (2010/2011). The flow volume recorded at Upper Niger at Koulikoro was about 26.80 billion m3 and compared with 35.79 billion m3 recorded previously showed a decrease of about 25%.

At the Lower Niger at Jiderebode the total volume was 26.69 billion m3 while that recorded in the previous year was about 42.78 billion m3 showing a decrease of about 60%. In the Inland Delta the decrease was about 36% and in the Middle Niger it was about 32%.

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The Black flood from Guinea has began to reside since the beginning of January in the Middle Niger, while the flows tend to the minimum in the Upper and Lower Niger basins. With an average monthly flow of 1348 m3/s (below average monthly interannual), the flow recorded in Niamey is significantly lower than those of the year 2010/2011. In the Inland Delta, where the flow began to reside since the beginning of December 2011 has an average monthly flow of 841 m3/s that is less than the fiveyear dry as observed at station Dire.

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As the low flow has continued in the Upper Niger and the Inland Delta in December 2011, the black flood flow has continued arriving at the Middle Niger in Niamey with a mean flow discharge of 1490 m3/s (lower than dry five year return). At the Inland Delta the flow that has already reach its maximum is now decreasing in December 2011 with mean of 1405 m3/s (also lower than Dry 5 year return period)at the gauge station at Dire.

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