Mathematical Modeling for Simulating Groundwater flow in small part of Niger Delta, Nigeria: A Case Study

The study focused on the assessment of groundwater flow from over exploitation of water table in the northern part of Niger Delta in Nigeria. Due to semi arid climate and water shortage, the effect of abstraction with respect to recharge is not well assessed and the aquifer storativity and groundwater flow pattern is not known. The local litho-stratigraphy of the area comprises of lateritic on the top soil and gravely medium to coarse sand to the subsequent layers. An area of 2053 square km has been modeled with a grid of 20 rows by 30 columns and twenty layers. Permeability distribution varies from 2.16 to 328.32 m/day. Precipitation is only source for natural recharge to the aquifer, and drawdown from the wells is only the abstraction from the aquifer. Groundwater flow modeling is studied to simulate the three dimensional groundwater flow direction. A steady state, three dimensional groundwater flows is analyzed using the U.S. Geological Survey groundwater flow model, MODFLOW that uses block-centered finite difference scheme for saturated zone. The model computations have converged after 50 iterations. Results from the modeling shows that abstraction is much more than groundwater recharge. Flow pattern of groundwater is towards the southeast potion of the study area. This places plays predominant role in recharge. Discharge area lies in the north east of the study area. The direction of the groundwater is governed by the mid topographic elevations causing the flow towards the east and west side of the study area