Water Level and the Potentials for Wetland Formation and Sustainability in Lower Ogun River Floodplain, Nigeria

Abstract

Identification, delineation and monitoring of wetlands which requires the understanding and application of their ecological characteristics are critical factors in wetland management and conservation. This study assessed the potentials of wetland formation and sustainability in the lower Ogun river basin by determining the levels of surface and ground water. The study area was divided into 1 km2 grids of 67 units using 0.052 %  sampling intensity for the assessments in dry and wet seasons. Monthly water table levels were assessed in 50 cm soil pit while inundation levels were measured during the flooding event using staff gauge. Assessment was carried out for one year during which frequency and periodicity of water table and inundation events were recorded. Results revealed that low water table level ranged from 5 to 45cm of soil depth and occurred between August and September within 6 grids. Water table and surface water was recorded within a period of 2 – 10 weeks during the rainy season. The peak of water levels coincided with the peak of precipitation (> 200 mm) ranging from 30 to 280 cm between September and October while covering 28.75 km2. Conclusively, surface and groundwater levels were recorded during the rainy season having direct variation with the volume of  precipitation for a duration that is long enough to support the formation of wetland hydrophytes and hydric soil.

Keywords: Wetlands; Hydrology; Ground water; Surface water; Inundation; Precipitation