Identifying Transboundary Aquifer hotspots in the SADCregion GeertJan

Identifying Transboundary Aquifer hotspots in the SADC-region. Geert-Jan Nijsten Karen G. Villholth

Transboundary Aquifers in SADC � 35 known TBAs in SADC ◦ 25 TBAs fully in SADC 10 Fully in SADC 25 Partially in SADC ◦ Non-SADC countries: Gabon, Congo, Central Africa Republic, Uganda, Rwanda, Burundi, Kenya ◦ Majority of TBAs shared by 2 countries only 1 1 2 countries sharing N 3 countries sharing 4 countries sharing 5 countries sharing IGRAC, UNESCO-IHP (2015), Nijsten, et al. (2018) 9 24

TBA hotspots Thematic approach 1 3 2 SADC 4 Villholth et al. (2011) Colvin et al. , 2012 Ø Urbanization (1) Ø Groundwater dependent ecosystems (2) Ø Transfrontier conservation areas (3) Ø Groundwater quality (4) Villholth et al. (2011)

TBA hotspots Indicator based approach Transboundary Waters Assessment Program (TWAP): � 20 indicators, of which 9 where also modelled. � 5 hotspots under future conditions based on: ◦ Groundwater development stress & ◦ Humand dependency on groundwater UNESCO-IHP, UNEP (2016), Riedel and Doll (2015)

TBA hotspots Indicator based approach - simplified Current state Groundwater development stress Human dependency on groundwater Groundwater quality (natural / antropogenic) Risks / hotspots High current risk Future development Ecosystem dependency on groundwater Vulnerability to climate change High future risk Vulnerability to pollution IGRAC, UNESCO-IHP (2016) Transboundary legal & institutional framework

Thank you Geert-Jan Nijsten: geert-jan. nijsten@un-igrac. org Karen Villholth: k. villholth@cigar. org

References � � � � � Colvin, C. , Maherry, A. , Roberts, W. and Le Maitre, D. , (2012? ) Mapping aquifer-dependent ecosystems at the SADC Scale: Methods and results. Poster presentation. IGRAC, UNESCO-IHP, 2015. Transboundary aquifers of the world [map]. 15 Scale 1: 50 000, edition 2015. IGRAC, Delft, Netherlands. IGRAC, UNESCO-IHP, 2016. IGRAC GGIS: TWAP Groundwater data and information portal. Data from UNESCO-IHP, UNEP, 2016. Transboundary Aquifers and Groundwater Systems of Small Island Developing States: Status and Trends. Transboundary Waters Assessment Programme TWAP. Online, URL: http: //twapviewer. un-igrac. org. IGRAC, UNESCO-IHP (2016) TWAP groundwater additional analyses (unpublished) Nijsten, G. , Christelis, G. , Villholth, K. G. , Braune, E. , Gaye, C. B. , (2018 in press) Transboundary aquifers of Africa: Review of the current state of knowledge and progress towards sustainable development and management https: //doi. org/10. 1016/j. ejrh. 2018. 03. 004 Riedel, C. , Döll, P. , 2015. Global-scale modeling and quantification of indicators for assessing transboundary aquifers. In: GEF Transboundary Waters Assessment Programme (TWAP). Frankfurt. SADC (? ) https: //www. sadc. int/themes/natural-resources/transfrontier-conservation-areas/ UNESCO-IHP, UNEP, 2016. Transboundary aquifers and groundwater systems of small island developing states: status and trends. Transboundary Waters Assessment Programme TWAP. UNEP, Nairobi. Villholth, K. , Tøttrup, C. , Stendel, M. , Maherry, A. , Claassen, M. , Chikozho, C. , Colvin, C. (2011) SADC Regional Groundwater Drought Vulnerability Mapping