Investigating the diminishing borehole yields in Malawi case study of Nankumba in Mangochi district

Abstract

As Malawi joins the whole world to achieve universal access to safe water for all by the year 2030, some boreholes in Traditional Authority Nankumba in Mangochi District in Malawi were said to have diminishing yields as reported in the Final Evaluation Report of the ICEIDA WaSNan Project. The study therefore aimed at investigating these diminishing boreholes yields to understand the extent to which they exist. Pumping tests were conducted and parameters such as static water level, dynamic water level and borehole yield were analysed. The study revealed that six (6) boreholes (9%) out of seventy (70) studied boreholes had problems to do with yield. One (1) borehole had completely dried up despite having a very good yield of 1.0 litre per second in its initial status while five (5) boreholes had yielded poorly with yields ranging between 0.08 to 0.19 litres per second. The study also revealed that the groundwater level had gone deeper as evidenced by deeper static water levels for almost all the boreholes. It also revealed that all the boreholes that had yield problems also had static water level as well as dynamic water level problems. The study also analysed construction field data of the studied boreholes in order to understand if any of the construction factors might have had influence on the diminishing borehole yields. It was revealed that four (4) out six (6) boreholes with yield problems had the lowest initial yield of 0.2 litres per second. The study therefore concludes that the diminishing yields exist but in lesser cases (9%) than what was earlier reported as being at 44%. It also concludes that there were problems of groundwater recharge such that groundwater levels were greatly affected. On the other the study showed that there were more mechanical problems affecting the functionality of boreholes than the yield problems.