Optimisation of national groundwater monitoring network of Lesotho

Nketsi, Mpoetsi
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Groundwater resources are a major source of water supply in Lesotho, particularly for the rural communities that rely on them for drinking, irrigation and domestic uses. However, Lesotho has been failing to meet its water demand due to an increase in demand and low supply caused by variations in climatic conditions. Furthermore, the emergence of textile industries, increasing urbanisation, and mining activities seem to be affecting groundwater resources negatively as well. Therefore, regular, systematic monitoring of groundwater resources is necessary to establish effective management. The aim of the study was to review and evaluate how optimised the groundwater monitoring network was on the basis of the geological and hydrogeological status.. The present national groundwater monitoring network was evaluated based on its geological and hydrogeological status. Through delineation of catchments using HECGEO-RAS and Global Mapper, results showed that the country is predominantly covered by basalts from the Drakensberg Group and has four major aquifers: sedimentary (fractured aquifers), basaltic aquifers, dyke-related and alluvial aquifers. Water levels range between 5and 42metres below ground level. Groundwater recharge is 4.24% of Mean Annual Precipitation (MAP) in the lowlands (Maseru) and 9.04% of MAP in the highlands (Mohale’s Hoek). A review process was then followed to identify gaps in the existing network. It was noted that amongst all limitations, the biggest one was data management and storage. On the basis of these findings, it is recommended that to optimise the network, the national groundwater monitoring network should increase its monitoring points in areas that were less prioritised, carefully select parameters to be monitored, increase monitoring frequency, and make use of a centralised database. Furthermore, to meet the set Quality Assurance/Quality Control (QA/QC) standards, institutional frameworks should invest in training and capacity development
A research report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Hydrogeology, 2021