Global Journal of Engineering, Design & Technology
Open Access

Abstract

Quantification of Groundwater Recharge in the River Oda Catchment using the Watertable Fluctuation Method

Atta-Darkwa, T., Kyei-Baffour, N., Ofori, E., Mensah, E. & Agyare, W. A

Quantification of groundwater recharge differs in their methods of estimation and therefore gives variable recharge estimates whenever a groundwater system is evaluated. Quantifying the fraction or the percentage of infiltrated water which reaches the watertable is a key factor in any sustainable planning scheme for groundwater resource management. The watertable fluctuation method was used to evaluate the seasonal and annual variations in water level rise and to estimate the groundwater recharge. The results showed that annual water level rise ranged from 1105-3115 mm in 2009 and from 397-3070 mm in 2010. A range of specific yields have been extracted from the values determined from the soil textural classification triangle. The estimated recharge for the study area ranged from 133-467 mm for the fourteen (14) piezometers installed for the study, representing 9- 31% of the 2009 annual rainfall and 47.6-427.9 mm, in 2010 representing 4-34 % of the annual rainfall. The area-weighted mean recharge was 341 mm in 2009, representing 21 % of the mean annual rainfall and 276 mm in 2010, representing 22 % of the mean annual rainfall. Also results of groundwater recharge rates for three monthly periods show that March-May experienced the highest recharge rate in 2009 and April-June in 2010. The lowest recharge rate was showcased from November-January with 26.4 mm and December-February with 26.9 mm. The recharge rates show that in the drier season around December, irrigation water should be applied based on the cropping season to obtain optimal moisture content and watertable levels.