A conceptual model based framework for pragmatic groundwater-quality monitoring network design in the developing world: application to the Chikwawa district, Malawi

Significant need exists in the developing world to transition from occasional groundwater-quality surveys to routinely sampled groundwater-quality network monitoring programmes that provide better safeguard of resources. Such networks contribute to the sustainable management of water resources, are integral to Water Safety Plans, and underpin delivery of Sustainable Development Goal 6. A framework for groundwater-quality monitoring network design is developed that is pragmatic for developing-world needs and its application is demonstrated using data from the Chikwawa District – Shire Valley aquifer system in Malawi. The step-wise framework is based upon a hydrogeological–hydrochemical process-based system conceptual model. The Chikwawa model developed is built upon our interpreted 2012 and archive 2008–9 major-ion survey data; major-ion data often constitute the most easily available datasets in many areas of the developing world. A versatile, semi-quantitative, approach is adopted which sets bespoke-system ‘Monitoring Objectives’, which are weighted on a scale of 1–5 and then rated against bespoke criteria using a scale of 0–10. This permits development of aggregate ‘Monitoring Potential’ scores at candidate network-point localities. Ideally the process is facilitated by the use of a GIS, although its use is not essential. Monitoring objectives are flexible and typically relate to various perceived risks to groundwater quality; including increasing salinity, anthropogenic activity, etc. The framework, as demonstrated for Chikwawa, allows an incremental build of a prioritised network of points, including a relative estimate of their potential to address the individual monitoring objectives set. The framework methodology is easy to use and adaptable to developing, and developed, world monitoring needs alike. The proposed network for Chikwawa could help pilot transition to a higher resolution national groundwater quality network across Malawi than currently exists. However, attaining the spatial monitoring densities suggested remains challenging due to the investment required in current infrastructure-capacity alongside the need to develop mechanisms that allow network running costs to be met sustainably.