Evaluation of Groundwater Suitability for Irrigation in the Lambussie-Karni District of Ghana

Abstract

The populace of the Lambussie-Karni District are mainly farmers who have resorted to the use of groundwater for irrigation during the dry season because of long drought and inadequate surface water bodies. The temporal variation of the groundwater quality for irrigation in the District was assessed using sixteen boreholes. Richard Plot indicates that groundwater in the study area is within the low salinity to low sodium hazard and medium salinity to low sodium hazard class. Wilcox Plot shows groundwater to be within excellent to good class in the catchment. Irrigation water quality index (IWQI) map was also developed to determine precisely the degree and areal extent of groundwater suitability for irrigation. ArcGIS 10.1 was used to generate thematic maps for sodium adsorption ratio (SAR), residual sodium carbonate (RSC), permeability index (PI), sodium percentage (Na %), HCO₃^-, pH and electrical conductivity. The results were compared to Food and Agricultural Organisations (FAO) standard guidelines. An IQWI map for the Lambussie- Karni District shows that groundwater is generally suitable for irrigation, about 24.57 % of the district will require crops which can tolerate high amount of salts. A percentage (39.82 %) of the catchment has groundwater, which is highly suitable for crops which are least resistant to salt.

Keywords: Groundwater Suitability; Irrigation Water Quality; SAR; IWQI Map; Lambussie-Karni District