Effects of Oil Production on Groundwater Levels in Lokichar Basin, Turkana County. Kenya
Gitari, Franklin Muchiri
MetadataAfficher la notice complète
Oil production requires large volumes of water for hydraulic fracturing. Globally, water demand for oil production has been increasing over the past decade. Kenya successfully completed the Early Oil Pilot Scheme (EOPS) project which was being undertaken in Lokichar basin in Turkana County in 2020 and expects to commence full commercialization in 2022. Water required for oil production during the EOPS was being obtained from ten boreholes drilled in the study area. Increased groundwater abstraction leads to decline in water levels. This study sought to investigate the effects of oil production on groundwater levels in Lokichar basin in Turkana County, Kenya. The specific objectives for this study were: to establish changes in groundwater demand in Lokichar basin, to determine borehole water levels in Lokichar basin and to establish rainfall trends in Lokichar basin. The changes in groundwater demand were related with the changes in borehole water levels to identify relationship. With rainfall being the major agent of groundwater recharge in the area, rainfall trends were analysed to establish whether it is contributing to groundwater level changes. Water levels for two boreholes within the study area were recorded between 12th August to 11th September 2020. To analyse rainfall trends, CHIRPS rainfall data for the study area was adopted. Kenya Ministry of Water and Irrigation design manual guidelines were adopted in estimating groundwater demand. Study findings showed that groundwater demand in Lokichar basin increased from 1,846,001.55 l/d in 2009 to 4,951,043.44 l/d in 2019 and is projected to increase to 145,235,374.23 l/d when full commercialization of the oil fields begins in 2022. This represents an increase in groundwater demand of 168% and 2833% for the periods 2009-2019 and 2019-2022 respectively. On borehole water levels, the study showed that the average daily levels remained fairly constant with Chinese 1 and Nawoyatira boreholes registering average daily water level of 18.12m and 19.5m respectively. The study however found out that major decline in borehole water levels is experienced during peak hours with levels declining to 29.0m and 26.6m for Chinese 1 and Nawoyatira boreholes respectively. Incorporation of oil production water demand into abstraction results to further decline in water levels to lows of 74m and 61m for Chinese 1 and Nawoyatira boreholes respectively. The study showed no statistically significant trend in the rainfall patterns between 1981 to 2019. The average annual rainfall amount was obtained as 142.48mm. The average annual groundwater recharge was estimated at 21.37mm. From the study findings, it has been concluded that increased groundwater abstraction led to borehole water level decline which is further exacerbated by incorporation of oil production water demand. It has therefore been recommended that an alternative source of water be identified during full commercialization of the oil fields to avoid overreliance on groundwater for oil production. Turkana County government should enact policies aimed at protecting the Laggers which are the main agents of groundwater recharge. Further research should be carried out to establish the extent of groundwater level changes during full commercialization of the oil fields.