The Niger River bifurcates into the Nun and Forcados rivers as it flows through the Niger delta, with the Forcados River taking 46% of the discharge and the Nun River taking 54%. Within the last fifteen years the Niger delta coastal zone has experienced peak floods between September and October due to intense rains from upstream. Many studies including the United Nations Framework on Convention on Climate Change (UNFCCC) indicate that the Niger delta region could be inundated with water due to the effects of climate change. According to local experts, the Niger delta is subsiding at over 25mm/annum; a situation that can exacerbate the effects of flooding and inundation in the area. 1D and 1D/2D hydrodynamic Sobek models of flooding in the Niger River were set up with discharge data as upstream boundary conditions and tidal water level data as downstream boundary conditions. The models were run for the years 1998, 2005, 2006, and 2007; the data for 1998, 2006 and 2007 were flooding data while 2005 data was normal flow data. The boundary conditions were varied downstream, at the mouth of rivers Forcados and Nun using sea level rise (SLR) values adopted from the Rhamstorf predicted values; the simulations were projected for the years 2030 and 2050. Five scenarios were set up to check for increase in flooding extent, extension of flooding time and change in water depth. The results showed that SLR will not increase the extent of flooded areas from both Nun and Forcados rivers, but will increase the water depth in areas downstream of the Forcados River. Furthermore with land subsidence the values for water depths downstream of the Forcados River doubled the values obtained from SLR only simulations.
Musa, Zahrah Naankwat; Popescu, Ioana; and Mynett, Arthur E., "Modeling The Effects Sea Level Rise On Flooding In The Lower Niger River" (2014). CUNY Academic Works.