Effect of Sand mining on Ground Water in Kano River Catchment

Abstract

This study assesses the impact of sand mining on wells situated within 1km radius of Wudil river channel. The channel was divided into three sites consisting of (i) Upstream of the active mining (ii) Active mining area (iii) Downstream of active mining area. The upstream of the mining site was assumed to be unaffected by sand mining and was thus considered as reference site. The mining site was an area of active sand mining. The downstream area is the area with no active mining but, within the impact of the mining activity. In order to determine the impact of sand mining, an inventory of bore holes, wash bore and open wells within one kilometer radius in the three sites was taken and fifty water samples at each of the three sites at various flow levels was taken for nephelometric turbidity analysis. To determine historic changes on the wells such as age of wells and well failure rate, interview was conducted with 25 respondents who use wells for irrigation, domestic and other purposes in each of the three sites. The officer responsible for the Wudil regional water scheme that operates 90% of all boreholes in the area was also interviewed. The results shows a marked variation in the location, failure rate, longevity and levels of turbidity  in the wells between the sites suggesting that sand mining has impacted negatively on the ground water quality and quantity. The study recommends a basin scale study and simulation study in order to garner more information that will allow for sufficient understanding that is required for the regulation of mining activity.

Key words: water quality, contamination, aquifer, water resources, irrigation, stream ecosystem