Groundwater resources management in the Afram Plains area, Ghana

A groundwater flow simulation model was developed using available hydrogeological data to describe groundwater flow in the Afram Plains area. A nonlinear optimization model was then developed and solved for the management of groundwater resources to meet irrigation and household needs. The objective was to maximize groundwater extraction from the shallow aquifers of the southern Voltaian Sedimentary Basin that underly the area, for irrigation activities. This would improve food security, raise the standard of living and ultimately help towards poverty alleviation in the rural communities that constitute the Afram Plains district. The calibrated flow model is in tandem with the general hydrochemical evolution of groundwater in the area and fits the observed data with about 98% degree of confidence. The study reveals that groundwater resources, if fully developed, may not be the limiting factor in the development of the irrigation industry, and has tremendous potential to meet current and future irrigation needs. Six groundwater management periods (January 2007–December 2013) were used for the study, with the quantity of irrigable land available, and the groundwater level drawdown as the main constraints that limit the maximization of groundwater extraction from wells for irrigation and household purposes. Maize was used as the single irrigation crop because maize appears to be the staple food and farmers are familiar with it in the area. It was determined from this pilot study, that profit from maize irrigation in the Afram Plains area could rise from US$ 301,000 in 2007 to over US$ 3.5million at the end of the last management period (2013) as irrigation practice is improved, and the economic strength to increase the acreage for irrigation improves. Even with these margins of profit, the drawdown constraint was not reached in any of the management periods. It is expected that recharge from the irrigation water would reclaim the lost hydraulic head. The single significant constraint was the amount of land area that could be developed for irrigation in the area. The profit obtained per unit cubic meter of water used also improved over the same management period.