Program Hydrogeologist, Baseflow, Malawi A review of climate change impact understanding on ground water recharge and baseflow in the SADC region. Steve Kumwenda, Program Hydrogeologist, Baseflow, Malawi

A review of climate change impact understanding on ground water recharge and baseflow in the SADC region. Steve Kumwenda, Program Hydrogeologist, Baseflow, Malawi Preliminary sharing Presentation Outline Background introduction Objectives and methodology Review Rationale Findings and Discussion Conclusions Recommendations

2.5% freshwater, 0.3% renewable Introduction Ground water covers over 95 % of the world’s available freshwater. (Howard, et al., 2009). 75 % of safe sources of drinking water in the SSA are from ground water (Foster, 2006). However, not easy to observe Climate Change impacts on ground water –Indirect and take long to observe This affects understanding and policy 2.5% freshwater, 0.3% renewable

Introduction ctd.. Interaction between climate change and ground water is not well understood (UN, 2011) - Inadequate research Mostly hypothetical analyses on the topic (IPCC, 2001). Aquifers are recharged by effective rainfall, An alteration in effective rainfall will affect ground water recharge E.g. In Tanzania, decrease by 15% of rainfall - led to a decrease of groundwater recharge by 40 to 50% (Sandstrom, 1995) A 20% reduction in average annual rainfall in central parts of Southern Africa - 80% decrease in recharge (Cave, et al., 2003.)

Objectives and Methodology To bring to light the current literature understanding of climate change impact on ground water in the SADC region. Add value to researchers in ground water and climate change impact interaction Methodology Systematic reviewing of published and grey literature search engines such as google (scholar), Microsoft edge , Strathclyde University libraries. The key words used in searching were ground-water, climate change impact, and Sub Saharan Africa, Literature time frame - from 1995 to 2018.

Rationale Ground water - alternative relief source (Portmann, et al., 2013) Due to impacts on surface water - vulnerable water resource E.g. In central Malawi over 250,000 affected Most feared impact - alteration of the hydrological system (Gleick, 2000) African countries - more prone to suffer, (IPCC, 2001) Inadequate institutional capacity slowed economic development- Climate Change, Not a priority

Rationale ctd.. Why do we seemingly have “infinite” groundwater? Africa has warmed by 0.7 ℃ while rainfalls have decreased by 5 to 15 % over the 20th century A further temperature rise projection of 1.5 ℃ by 2050 has also been indicated. Why do we seemingly have “infinite” groundwater? The world’s sedimentary aquifers- recharged some thousand years ago e.g., the Southern Africa Kalahari sands, North Africa Nubian Sandstone aquifers (R.G. Taylor, 2013) Such regional aquifer basins are storage dominated rather than recharge flux dominated (Foster, 2006) And therefore non-renewable Major impact –ground water over-abstraction vs surface water

Review Rationale ctd.. Climate Change Impact - ground water storage through changes in recharge. (Green et al, 2011). (Crosbie, et al., 2013) Therefore, an understanding of the future recharge rates is required UNESCO indicates relatively lack of research studies addressing the impacts of climate change on ground water. (IPCC, 2007) Research has greatly focused on surface water A few ground water models have been developed on ground water Climate Change impact (Cooper, et al., 1995) A lot of impacts currently are un predictable and remain speculative

Findings and Discussion Ground water is less responsive to short term climatic variability compared to surface water. (Bonsor, et al., 2010) Relationship between rainfall intensity and ground water recharge - not outright direct Recharge patterns - affected by soil degradation and vegetation changes The BGS undertook a study on Ground Water resilience to climate change Across Africa. (MacDonald, et al., 2011) Ground water maps for Africa However, Regional level focus- National application needed

Findings and Discussion ctd.. Groundwater aquifer maps for Africa Estimated groundwater storage for Africa (left) and aquifer productivity map across Africa(right) Source: MacDonald et al. 2012; British Geological Survey NERC 2011, Used with permission  

Findings and Discussion Why slow breakthroughs? The BGS notes hydrogeological data is missing hydraulic conductivity, transmissivity, Storativity/storage are rarely available. Most basic available data on hydrogeology is from geology, borehole depth and borehole yield. Before 2007 ground water research studies were rare Currentlty studies are mushrooming (Jiménez, et al., 2014) 4 to 20 Global Models on impact of Climate change on Ground Water However, regionally and nationally there still challenges

Findings and Discussion ctd.. UNESCO notes hydrogeology – relatively young discipline (Foster, et al., 2006). Only in recent years that ground water experts began to understand the groundwater climate change interactions Other studies coming up that will enhance understanding of ground water first E.g.  BGS - Africa regional aquifer storage atlas, Malawi also has a project on CGS atlas of aquifers University of Strathclyde works on transboundary aquifer and Shire river basin conjunctive use with SADC GMI

Conclusion The most feared impacts of climate change Limitations Alteration of the hydrological cycle- ground water recharge Though the link between rainfall and aquifer recharge- Not outright direct (Bonsor, et al., 2010) Ground water storage depletion as an alternative source to drought impacted surface water Limitations Not exhaustive – but a current understanding regarding the topic. The paper is still being worked on – for publication

Recommendations Water sector development agencies and Governments in the SSA National level mapping of ground water aquifers, basins This conference - substantial research is being generated Support ground water data collection on aquifer properties/ characteristics Ensure Adequate skilled technical personnel to engage in such ground water data MIS. Need for more Ground water flow modelling trained professionals. Enhance the already regional joint research and monitoring programs Regulation of ground water use - over abstraction Need for renewed understanding of ground water recharge dynamics in relation to the current and expected climate change. (Burney, et al., 2013)

Recommendations ctd.. Scale up of the Hydrogeology as an academic discipline, Undergraduate and Post Continuous Professional Development. This is one key area that the SADC GMI is collaborating -University of the Free State, -UNESCO IHP -University of Strathclyde

(care for the water upon which you depend) Thank You. …Into the well from which you drink do not throw stones...Arabic proverb (care for the water upon which you depend)