Module 7 GROUNDWATER AND CLIMATE CHANGE

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1 Module 7 GROUNDWATER AND CLIMATE CHANGE

2 Learning Objectives To become familiar with the basic concepts of the impacts of climate change on groundwater To explore the link between climate change impacts and groundwater resources

3 Introduction Changes in mean annual rainfall, as well as in its temporal and spatial distribution influences the water balance as a whole, and groundwater recharge. Climate change will manifest itself by modifying rainfall and evaporation patterns in River basins and by altering the hydrological balance.

4 .continued The causes of climate change rests primarily with industrialised nations and yet The implications of climate change will be borne most directly by the poor

5 continued Groundwater responds much more slowly to changes in the meteorological conditions than surface water and due to its resilience, provides a natural buffer against climate variability.

6 Drought as a proxy to climate variability Changing climate induces changing groundwater resources availability and utilization Source: Calow et al., 1997

7 What is climate variability? Climate Variability (Variation/fluctuation) refers to a deviation of climate from the Long-Term meteorological average over a certain period of time, e.g. a specific month, season or year. Variations are a natural component of the climate caused by changes in the System/s that influence the climate such as the General Circulation system.

8 Causes of climate variability One of the systems that is known to result in some of the major fluctuations of climate in many tropical parts of the world is the El-Nino Southern Oscillation (ENSO) event. Warm ENSO: El-Niño Cold ENSO : La-Nina

9 El-Niño The term El Niño, (Spanish word for "the Christchild"), refers to periodic building up of a large pool of unusually warm waters in large parts of the eastern and central equatorial Pacific Ocean Take place at varying degrees of magnitudes and periods.

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11 La Niña La Niña is the opposite of El-Niño Used to describe periodic building up of unusually cold waters in large parts of the large parts of the eastern and central equatorial Pacific Ocean. The atmosphere and the neighbouring oceans respond to El Niño and La Niña events in various ways

12 What is climate change? Climate Change: refers to a permanent shifts in the traditional space-time patterns of climate, e.g. change from one climate mode to another climate mode, which is outside the normal range of natural climate variability regardless of the causes.

13 Causes of climate change 1. NATURAL DRIVERS Due to the variation of the orbital distance of the Earth from the Sun. This leads to the cold - glacial and warm inter-glacial periods. Each period lasts about 100,000 years. The change is so slow that we do not easily notice. Due to sun's activity: Solar cycle of 22 years

14 Causes of climate change 2. MAN MADE DRIVERS (ANTHROPOGENIC) Greenhouse gases Some land use changes Urbanization Aerosols The increase in the CO 2 is predominantly because of burning fossil fuels

15 Greenhouse effect The greenhouse is a natural process mainly due to the effect of water vapor. The earth without the greenhouse effect would be 33 o c colder. The potential climate change is due to the increase on the greenhouse effect due to emission of gases of the human activities, increasing the temperature. The main gases which could increase this effect in the atmosphere due to human activities were identified as: CO 2, (CH 4 ), nitrogen oxide; CFC (chlorofluorocarbon).

16 Climate change scenarios 1. Average temperatures are likely to increase: Africa as a whole, warming in the 20 th Century occurred at a rate of about 0.5 c across the century, and that the rate of warming increased in its last three decades. 2. Annual rainfall is likely to fall in the northern Sahara and in southern Africa, and is likely to increase in the East Africa 3. Rainfall is likely to become increasingly unpredictable in terms of both intensity and duration, with increases in the frequency of extreme events - droughts and floods

17 Interaction between climate change & groundwater Source: Taylor et al. (2013)

18 Climate Change Impacts Groundwater Recharge Groundwater recharge can occur locally from surface water bodies or in diffuse form from precipitation. Recharge is not only influenced by the magnitude of precipitation, but also by its intensity, seasonality, frequency and changes in land use. Recharge is very important in regulating the volume of groundwater. Reduction in recharge will reduce the volume of renewable groundwater.

19 Climate Change Impacts Output component: Evapotranspiration, runoff, groundwater discharge into streams and springs and pumping Drying up of springs, streams Output

20 Climate Change Impacts Groundwater storage Groundwater storage is the balance between input and output over a given period of time. Storage within the renewable aquifers will be reduced due to reduced recharge. Climate change forces people to overabstract renewable aquifers and hence depletion of storage. High pumping rate results aquifer drying

21 Climate Change Impacts Water quality Soil salinization due to extreme evaporation Flooding due to high rainfall and pollution from sanitation

22 Expected changes as a result of climate change Changes in precipitation frequency and intensity: In addition to changes in global average precipitation there could be more pronounced changes in the characteristics of regional and local precipitation due to global warming. On average, precipitation will tend to be less frequent, but more intense, implying greater incidence of extreme floods and droughts, with resulting consequences for water storage.

23 Expected changes as a result of climate change Changes in average annual runoff: -decreases in runoff due to higher temperatures which lead to higher evapotranspiration losses. -increase runoff due to prolonged rainfall

24 Climate Change and Population Growth Population growth has intimate relation with climate change that aggravates water demand, increased food demand, land use change, and socio-economic factors that influence the capacity to appropriately manage the groundwater resource.

25 Most vulnerable rural communities

26 What is adaptation? Adaptation is a process by which individuals, communities and countries seek to cope with the consequences of climate change, including climate variability. It should lead to harmonization with country s more pressing development priorities such as poverty alleviation, food security and disaster management.

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28 Adaptation Prevent Mitigate and adapt!

29 Adaptation In order to cope up with the climate change, an integrated approach to climate change that embraces both mitigation, which addresses the drivers of climate change, and adaptation, which considers the measures necessary to accommodate such changes. Adaptations are adjustments made in natural or human systems in response to experienced or projected climatic conditions or their beneficial or adverse effects or impacts.

30 Adaptation Options 1. Enabling communities to understand climate and hydrological risks Education and training Governance improvement Sharing information 2. Resource information Understanding climate Climate change projections Quantify the groundwater system, Monitoring, evaluation and reporting 3. Research & development Climate impact assessments Management of groundwater recharge, storage, quality Managing demand for groundwater

31 ...continued 4. Governance & institutions Conjunctive management of surface water and groundwater Multi-jurisdictional planning and resource management arrangements for large scale aquifer systems Defining water allocations based on resource share rather than volume Set and regulate standards Drought response planning 5. Establishment and operation of markets for water and associated environmental services Property rights establish clear title and property rights to groundwater

32 Managed Aquifer Recharge (MAR)

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