Transboundary aquifer assessments at the national scale : towards achieving sustainable development goal 6.5

‘Transboundary aquifer’ is the term given to a body of groundwater that is stored in a geological formation that cross an international or state border. Transboundary aquifers thus have the potential to transmit significant volumes of groundwater from one country to another. Transboundary water is a valuable natural resource which accounts for up to 40% of available drinking water and is essential in both agriculture and industry. Transboundary aquifers are, however, poorly understood scientifically and are underrepresented in international law and policy. This thesis addresses the need for countries to examine their transboundary aquifers at a national scale and prioritise them for national and local scale sustainable management. The case study of Malawi and its neighbouring countries of Mozambique, Zambia and Tanzania has been employed to do this. First, the current understanding of transboundary aquifers is examined highlighting the recent drive for transboundary aquifer management that has been growing since 2000. A critical assessment of the current status of the regional approach taken in assessing and identifying transboundary aquifers using a Malawi case study is presented. The popular approach risks only focusing on large, extensive aquifers and missing out smaller, more national and local scale aquifers that may be of importance at a smaller scale. A case is therefore made for systematic transboundary aquifer assessment along its national border length addressing both regional and minor local aquifer systems. Following on, a national border based assessment of Malawi’s transboundary aquifer units is conducted highlighting how best this approach can be done within a developing country context. A methodology for identifying hotspots within transboundary aquifers that may be vulnerable to the groundwater quality and quantity issues is then presented. This method is applied to the Malawi case study allowing for prioritization of transboundary aquifers for directed local level management based on vulnerability hotspot mapping. Finally, isotopic and geochemical techniques are utilised to examine one of these identified hotspots more closely. A conceptual model of the selected hotspot is developed to understand the transboundary implications of the area in greater detail and assist in local scale transboundary management. Throughout the thesis, the themes of multi-scale management of transboundary aquifers within a sustainable development context are also discussed. In order to achieve Sustainable Development Goal 6, and in particular, target 6.5.2, transboundary aquifers need to be understood and managed more effectively. National scale transboundary aquifer assessments, resource prioritization and multi-scale management can assist with this challenge.‘Transboundary aquifer’ is the term given to a body of groundwater that is stored in a geological formation that cross an international or state border. Transboundary aquifers thus have the potential to transmit significant volumes of groundwater from one country to another. Transboundary water is a valuable natural resource which accounts for up to 40% of available drinking water and is essential in both agriculture and industry. Transboundary aquifers are, however, poorly understood scientifically and are underrepresented in international law and policy. This thesis addresses the need for countries to examine their transboundary aquifers at a national scale and prioritise them for national and local scale sustainable management. The case study of Malawi and its neighbouring countries of Mozambique, Zambia and Tanzania has been employed to do this. First, the current understanding of transboundary aquifers is examined highlighting the recent drive for transboundary aquifer management that has been growing since 2000. A critical assessment of the current status of the regional approach taken in assessing and identifying transboundary aquifers using a Malawi case study is presented. The popular approach risks only focusing on large, extensive aquifers and missing out smaller, more national and local scale aquifers that may be of importance at a smaller scale. A case is therefore made for systematic transboundary aquifer assessment along its national border length addressing both regional and minor local aquifer systems. Following on, a national border based assessment of Malawi’s transboundary aquifer units is conducted highlighting how best this approach can be done within a developing country context. A methodology for identifying hotspots within transboundary aquifers that may be vulnerable to the groundwater quality and quantity issues is then presented. This method is applied to the Malawi case study allowing for prioritization of transboundary aquifers for directed local level management based on vulnerability hotspot mapping. Finally, isotopic and geochemical techniques are utilised to examine one of these identified hotspots more closely. A conceptual model of the selected hotspot is developed to understand the transboundary implications of the area in greater detail and assist in local scale transboundary management. Throughout the thesis, the themes of multi-scale management of transboundary aquifers within a sustainable development context are also discussed. In order to achieve Sustainable Development Goal 6, and in particular, target 6.5.2, transboundary aquifers need to be understood and managed more effectively. National scale transboundary aquifer assessments, resource prioritization and multi-scale management can assist with this challenge