Simulation of groundwater flow in a crystalline rock aquifer system in Southern Ghana - An evaluation of the effects of increased groundwater abstraction on the aquifers using a transient groundwater flow model

Sandow Mark Yidana, Bob Alfa, Bruce Banoeng-Yakubo, Millicent Obeng Addai

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)

Abstract

Monitored groundwater level data, well logs, and aquifer data as well as the relevant surface hydrological data were used to conceptualise the hydrogeological system of the Densu Basin in Southern Ghana. The objective was to numerically derive the hydraulic conductivity field for better characterization of the aquifer system and for simulating the effects of increasing groundwater abstraction on the aquifer system in the basin. The hydraulic conductivity field has been generated in this study through model calibration. This study finds that hydraulic conductivity ranges between a low of 2m/d in the middle sections of the basin and about 40m/d in the south. Clear differences in the underlying geology have been indicated in the distribution of aquifer hydraulic conductivities. This is in consonance with the general assertion that the hydrogeological properties of the aquifers in the crystalline basement terrains are controlled by the degree of fracturing and/or weathering of the country rock. The transient model suggest aquifer specific storage values to range between 6.0×10-5m-1 and 2.1×10-4m-1 which are within acceptable range of values normally quoted for similar lithologies in the literature. There is an apparent subtle decrease in groundwater recharge from about 13% of the annual precipitation in 2005 to about 10.3% of the precipitation in 2008. The transient model was used to simulate responses of the system to annual increment of groundwater abstraction by 20% at the 2008 recharge rates for the period 2009 - 2024. The results suggest that the system will not be able to sustain this level of abstraction as it would lead to a basin wide drawdown in the hydraulic head by 4m by the end of the prediction period. It further suggests a safe annual increment in groundwater abstraction by 5% under business as usual recharge conditions. Identification and protection of groundwater recharge areas in the basin are recommended in order to safeguard the integrity of the resource under the scenario of increased abstraction for commercial activities in the basin.

Original languageEnglish
Pages (from-to)1084-1094
Number of pages11
JournalHydrological Processes
Volume28
Issue number3
DOIs
Publication statusPublished - 30 Jan 2014

Keywords

  • Densu Basin
  • Groundwater abstraction
  • Hydraulic conductivity
  • Recharge

Fingerprint

Dive into the research topics of 'Simulation of groundwater flow in a crystalline rock aquifer system in Southern Ghana - An evaluation of the effects of increased groundwater abstraction on the aquifers using a transient groundwater flow model'. Together they form a unique fingerprint.

Cite this