VULNERABILITY OF COMMUNITIES TO FLOOD HAZARD AND RIVERBANK EROSION ALONG RIVER NUN IN BAYELSA STATE, NIGERIA

Abstract

Perennial flooding leading to riverbank erosion has for a long time been a major ecological problem in Bayelsa State as in most parts of the Niger Delta. The scale of the problem and the magnitude of land lost due to bank erosion are exacerbated by the dense network of rivers and creeks in the area. The Nun River which runs through Okoloba and Sabagreia among other communities in Kolokuma/Opokuma exercises considerable influence on the hydrology and geomorphological characteristics of the area. Landslides, riverbank collapse and erosion have been common hazards in the area. This study involving the collection of a wide range of data from both primary and secondary sources. The degree of vulnerability and risk posed by flood hazard, recurrent landslides and riverbank collapse and erosion are assessed. The rate and magnitude of riverbank erosion were also determined using, the geographic information system (GIS) integrated with the use of historical satellite imagery of the communities. The results revealed that the average erosion rates for the past 13year period amounted to 1.1538 acre/yr on the left bank and 0.3077 acre/yr. on the right. Riverbank erosion has had adverse effects on cultivable lands, livelihoods and property damage and displaced several inhabitants. Shoreline protection measures, including embankment, the use of revetment of sand-filled permeable polyethylene for safety and enhancement of socioeconomic use of the shoreline is recommended.