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Beneath the Surface of Climate Change : Managing Natural Climate Variability toward Sustainable Groundwater. Jason Gurdak Coordinator of UNESCO GRAPHIC, Associate Professor Dept of Earth and Climate Sciences San Francisco State University, California USA. Photo credit: R. Johnson.
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Beneath the Surface of Climate Change: Managing Natural Climate Variability toward Sustainable Groundwater • Jason Gurdak • Coordinator of UNESCO GRAPHIC, • Associate Professor • Dept of Earth and Climate Sciences • San Francisco State University, California USA Photo credit: R. Johnson
Outline • Motivation: • Water-Energy-Food Nexus • Global groundwater crisis • Response to these Challenges: • GRAPHIC: Groundwater Resources Assessment under the Pressure of Humanity and Climate Change • Case Study: • Climate variability effects on African aquifers
Motivation – Global Trends Water-Energy-Food nexus concept – a response to climate change and social changes including population growth, globalization, economic growth, urbanization, growing inequalities, and social discontent: Urbanization: Population growth: 54% lives in urban areas today. 66% by 2050. 11 billion by 2100 By 2030: Demand for water, energy, foodestimated increase by 40%, 50%, 35%. (USNIC, 2013) Poverty: Climate change: Solutions? 1.1 billion lack access to clean water. 1.2 billion live in extreme poverty. Effects on: hydrologic cycle, food production, & energy use
Water-Energy-Food Nexus: Tradeoff & Conflict By 2030, demand for water, energy, and food increase by 40%, 50%, and 35% Socioeconomic development Climate change Planetary Boundaries Water - Energy Water-Food Global groundwater crisis Rockström et al. (2009) Fundamental goods & ecosystem services for human health : Tradeoff & Conflict Water Tradeoff & Conflict Energy Food pressure on groundwater
Alarming Groundwater Depletion Rates “Global Groundwater Crisis” (Famiglietti, 2014) What is the projected life expectancy of these important aquifers? These aquifers support the world’s most productive agricultural regions: Most of Sub-Saharan Africa has NOT [yet] experienced the groundwater crisis.
How does Climate Variability and Change affect Groundwater? IPCC …many questions remain about climate change and groundwater : “Several gaps in knowledge exist in terms of research needs related to climate change and water…” “…especially with respect to water quality, aquatic ecosystems, and groundwater.” Bates et al., 2008
Groundwater Resources Assessment under the Pressures of Humanity and Climate Change Science --- Education --- Outreach --- Global Network www.graphicnetwork.net • Vision: • Advance sustainable groundwater management under projected climate variability and change and coupled human activities. • Mission: • Platform for global research. • Science-based policy recommendations • Improve capacity to manage GW.
GRAPHIC Mission: Research GRAPHIC publications available: http://www.graphicnetwork.net/about/publications/
Study Regions: Global Network and Research Coordination Research Sites and Collaborators Study Regions 2. southwestern Uganda 3. southern Mali 4. Pipiripau River basin, Brazil 5. North Andros Island, Bahamas 6. Pacific Island countries 7. Iullemmeden Basin, West Africa 8. Souss-Massa Basin, Morocco 9. High Plains aquifer, USA 10. Murray Basin, Australia 11. Majorca, Spain 12. Israeli coastal aquifers 13. The Netherlands 14. British Columbia, Canada 15.Sante Fe Province, Argentina 16. Beijing Plain, China 17. esker aquifers, northern Finland 18. Svalbard, Norway 19. Asian coastal cities: Bangkok, Jakarta, Manila, Osaka, Seoul, Taipei, & Tokyo 20. European groundwater resources 21. Central Valley, USA
Scientific Findings and Policy Relevant Recommendations Research in 30 countries; 60 authors • Research Themes & Topics: • land subsidence • seawater intrusion • response to drought • response to permafrost melt • dependent ecosystems (GDE) • groundwater quality • GRACE: GW depletion rates • statistical downscaling; GCMs • ENSO, NAO, PDO, AMO • effects on recharge
GRAPHIC Mission: Education Training workshops for students and early-career scientists Groundwater@GlobalPaleoclimate Signals (G@GPS): paleogroundwater branch of GRAPHIC Sun Yatsen University, Zhanjiang, China (2014) Tallinn University of Technology, Tallinn, Estonia (2015)
GRAPHIC Mission: Outreach & Communication Translate our scientific findings into policy relevant recommendations Released 2 position papers at COP21: Gurdak et al., 2015
Become Involved with GRAPHIC • If you’re interested in becoming involved with GRAPHIC, please see or email: • Jason Gurdak (GRAPHIC Coordinator) • Marc Leblanc (GRAPHIC Coordinator) • Tales Carvalho Resende (UNESCO-IHP) • Alice Aureli (UNESCO-IHP) http://www.graphicnetwork.net • Volume 2: write this coming year • Solicit contributors/authors Sign up for our newsletter & mailing list:
Case Study - Motivation Many African countries have opportunity to avoid groundwater crisis, but lack weather and groundwater monitoring stations to support decision making. GRACE provides observations of terrestrial water storage changes (DTWS) Launched in 2002. DTWS = sum of water stored in vegetation, ice, snow, lakes, streams, soil moisture, and groundwater.
Interannual to Multidecadal Climate Variability Profoundly affects: precipitation, drought, streamflow, evapotranspiration, soil moisture, crop yields, irrigation requirements… and groundwater. El Nino/Southern Oscillation (ENSO) 1930s “Dust Bowl” 1950s drought McCabe et al., 2004
Interannual to Multidecadal Climate Variability North Atlantic Oscillation (NAO): 3–6, 8–10 year Atlantic Multidecadal Oscillation (AMO): 50–80 year El Niño/Southern Oscillation (ENSO): 2–7 year quasi-periodic oscillation Pacific Decadal Oscillation (PDO): 15–30 year Africa / South Africa: drier & droughts ENSO wetter North Africa: drier & droughts NAO wetter PDO Sahel (opposite Gulf of Guinea): AMO wetter Drier & droughts NOAA, 2017
How does Climate Variability Impact on Groundwater Storage in Africa? Tales Carvalho Resende et al., 2018, Hydrogeology Journal North-Western Sahara Aquifer System (NWSAS) Nubian Sandstone Aquifer System (NSAS) Senegalo-Mauritanian Basin Irhazer-Iullemmeden Basin Lake Chad Basin Volta Basin* Karoo-Carbonate Stampriet Transboundary Aquifer System* Karoo Sedimentary* * Aquifer area < limit of GRACE footprint. Most are transboundary aquifers.
Approach Goal: Quantify teleconnections between global-scale climate oscillations (ENSO, NAO, and AMO) and total water and groundwater storage. • Reconstructed past climate-driven changes in water storage variations in the 9 aquifers: • with climate-driven model using P and actual ET for period of 1982 to 2011, independent of the GRACE data. • GRACE: • Additive correction approach following Longuevergne et al., 2010. • Validation: • Compared modeled total water storage changes (DTWSmodel) with GRACE (DTWSGRACE) for period 2002 to 2013.
Approach • Validation – Cont’d: • DTWSmodeland DTWSGRACE compared to long-term piezometry measurements to show the extent that TWS covaries with observed groundwater storage changes (DGWSobserved).
Results Evaluate GRACE-based and climate-driven model estimates In general, the DTWSGRACE and DTWSmodel characterize DGWSobserved.
Results Correlation Coefficients: 0 –dark blue 1 – light yellow Wavelet Coherence (WTC) Analysis Identifies regions in time frequency space where two time series co-vary. 1 3 8 9 • WTC analysis indicates that DTWSGRACE,DTWSmodel , and DGWSobserved are strongly correlated. • Indicates that the shallow aquifers are highly responsive to rainfall temporal patterns.
Results Groundwater Storage Dynamics are Largely Correlated with African Climate Zones Northern Africa: North-Western Sahara Aquifer System (NWSAS) • DTWS good agreement with rainfall patterns and NAO and AMO variability. • 1980s: decrease in storage • Early 1990s: increase in storage • Late 1990s: decrease in storage • Mid-2000s: increase in storage DTWSmodel – NAO WTC plot • Groundwater storage appears correlated with NAO. • Three high coherence bands • Positive (negative) NAO phase largely correspond to decreasing (increasing) groundwater storage. • AMO exerts a low-frequency modulating influence on groundwater storage.
Results Groundwater Storage Dynamics are Largely Correlated with African Climate Zones Sahel: • Nubian Sandstone Aquifer System (NSAS) • Senegalo-Mauritanian Basin • Irhazer-Iullemmeden Basin • Lake Chad Basin • 4 aquifer systems have similar multi-decadal behavior: • 1980s – mid-1990s: Large decrease in groundwater storage. • Mid-1990s: large increase in groundwater storage. • AMO exerts a much more direct influence on GW storage in the Sahel than Northern Africa. • Positive (negative) AMO phase largely correspond to increasing (decreasing) groundwater storage.
Results Groundwater Storage Dynamics are Largely Correlated with African Climate Zones Tropics: Volta Basin Karoo Carbonate • Opposite patterns, less pronounced than Sahel response to AMO. • Supported by recent drying trends in central equatorial Africa and the Guinea regions, such as Benin and Nigeria. • Positive (negative) AMO phase largely correspond to decreasing (increasing) groundwater storage.
Results Groundwater Storage Dynamics are Largely Correlated with African Climate Zones Southern Africa: (c) Karoo Sedimentary & (d) StamprietTransboundary Aquifer System • Has strong inter-annual patterns, instead of multi-decadal pattern of northern Africa. • 1980s: decrease in storage • Late-1980s: increase in storage • Early-1990s: decrease in storage • Late-1990s: increase in storage • etc about every 2-7 years • GW storage appears correlated with ENSO. • Two or three high coherence bands • Positive (negative) ENSO phase largely correspond to drier (wetter) and decreasing (increasing) GW storage.
Summary & Conclusions • P and ET climate model to reconstruct past (1982 – 2011) climate variability, has limitations (lacks abstraction and land use data), but provides a robust and computationally inexpensive pointer of groundwater dynamics in shallow aquifers. • The DTWSGRACE, DTWSmodel , and DGWSobserved are highly correlated. • DTWSGRACE provides a tool to understand basin scale (>200,000 km2) groundwater dynamics in shallow aquifers. GRACE is NOT a tool for local groundwater managers. • NOA and ENSO are important drivers of interannual groundwater dynamics in Northern Africa and Sub-Saharan Africa (especially Southern Africa) respectively. • AMO important driver of decadal variability of groundwater dynamics in the Sahel • (positive/wet AMO phase since mid-1990s; shift could) bring drought and • groundwater level declines)
Implications • Findings can be used by decision makers to help prepare effect climate variability and change adaptation plans. • Groundwater governance – many reviewing and updating policies and laws • Integrate climate variability • Strengthening national meteorological, hydrological, and groundwater monitoring networks. • Strengthening institutional linkages between groundwater/surface water decision makers and meteorological institutions. • Provision for managed aquifer recharge (MAR)
Conclusions Managed Aquifer Recharge (MAR) • Groundwater management institutions could further incentivize MAR projects. • MAR operations should take advantage of temporal patterns of precipitation and enhanced recharge during wet phases of climate oscillations. • Preferred periods of MAR (i.e., wet phases): • Negative NAO in Northern Africa • Positive phase of AMO in Sahel • La Nina years in Southern Africa spring farmland winter MAR-ASR Low impact development (LID):
Thank you Jason Gurdak Email: jgurdak@sfsu.edu Photo credit: R. Johnson