Changes in flood risk in Lower Niger–Benue catchments

Abstract

Abstract. Floods are devastating natural disasters with a significant impact on human life and the surrounding environment. This paper analyses historical and recent flood (2012 extreme) peak flow at strategic locations, land use activities and Floodplain Vulnerability Index analyses of the Niger-Benue River Floodplain. The 2012 peak flow at Jederbode on the Niger River was about 50 % above the long term average. At Jebba (Niger), the 2012 peak flow of 1567 m 3 s −1 was also far higher than the long term mean annual peak flow of 1159 m 3 s −1 . The 2012 peak flow at Lokoja was also about 50 % above the historical average. The Benue River at Makurdi had peak flow of 16 387 m 3 s −1 which was also unusually higher than the historical average while Wuroboki (Benue) had peak flow of 3362 m 3 s −1 which was also much higher that the historical average (694 m 3 s −1 ). The mixed land use which supported diverse ecosystem services has the largest cover of 5654 km 2 (36.85 %) of the Niger-Benue floodplain. The flood vulnerability of the various land uses within the floodplain include; medium, high and very high levels. A four levels hierarchical implementation adaptation strategy for sustainable agricultural practices along the rivers flood plain was proposed. The implementation hierarchy includes: Community Concern, Local Authority Concern, State Concern and National Concern.

Infilling Missing Data in Hydrology: Solutions Using Satellite Radar Altimetry and Multiple Imputation for Data-Sparse Regions

“…The hydrology of the region is defined by inflow from the Niger River Basin through Niger and Benue rivers ( Figure 1B) travelling downstream to the Atlantic Ocean through the Nun and Forcados distributaries in the Niger Delta ( Figure 1C), and to the Anambra-Imo river basin through the Anambra river. The annual rainfall varies from 1100 to 1400 mm, while the land cover along the Niger and Benue river floodplains is comprised of built-up areas (0.68%), cultivated land (31.42%), plantations (0.04%) wetlands (9.70%), mixed land use (36.85%), grasslands (6.17%), water bodies (14.83%), and bare surfaces (0.31%) [43]. The average annual discharge into the Niger-South river basin form the Niger and Benue river catchment areas is 5381 m 3 /s [44], and has an average river with of 742 m [10].…”

Detecting Changes in Hydro-Climatic Variables during the Last Four Decades (1975-2014) on Downstream Kaduna River Catchment, Nigeria

“…Substantial efforts have been devoted to the study of hydroclimate variables [11]- [16]. Moreover, understanding the variations of rainfall, temperature and runoff at the basin scale provides opportunity to study the changing climate impact on water resources and hydrological cycle [17] [18] [19] [20]. For example, identified significant positive uptrend in rainfall is reflected in surface runoff yield [21] and rainfall effectiveness is considerably reduced due to high rate of water loss by evapotranspiration especially in the drier tropics.…”

“…Substantial efforts have been devoted to the study of hydroclimate variables [11]- [16]. Moreover, understanding the variations of rainfall, temperature and runoff at the basin scale provides opportunity to study the changing climate impact on water resources and hydrological cycle [17] [18] [19] [20].…”

Catchment-Scale Flood Modelling in Data-Sparse Regions Using Open-Access Geospatial Technology

“…Due to these high flows, many rivers within the Niger basin are dammed for hydroelectric power generation, irrigation or flood control purposes [28,29]. In recent years the Niger and Benue Rivers have been heavily influenced by excess water released from upstream dams in Nigeria, Niger and Cameroon [30,31], resulting in flooding of the low-lying settlements within floodplains [32][33][34]. The annual average rainfall in the region varies from 750 to 1600mm, and the annual average temperature ranges from 18 to 28C.…”

“…The study area was amongst the most affected areas during the unprecedented 2012 flooding [30,31]. The convergence of excess water from Niger and Benue rivers initiated flooding at Lokoja confluence [34]; the Onitsha/Asaba floodplain was flooded due to high upstream flow from Lokoja and river channel constriction that resulted in backwater effect [35]; and the Niger Delta region was flooded as a result of its low-lying topography and the influx of rising upstream water levels Lokoja and Onitsha [31].…”