Module 7

GROUNDWATER AND CLIMATE CHANGE

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

Learning Objectives

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.

Introduction

The causes of climate change rests primarily with industrialised nations

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The implications of climate change will be borne most directly by the poor

and

yet

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.

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Changing climate induces changing groundwater resources availability and utilization

Source: Calow et al., 1997

Drought as a proxy to 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.

What is 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

Causes of climate variability

El-Niño

The term El Niño, (Spanish word for "the Christ-child"), refers to periodic building up of a largepool of unusually warm waters in large parts ofthe eastern and central equatorial Pacific Ocean

Take place at varying degrees of magnitudes andperiods.

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

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.

What is 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

Causes of climate change

2. MAN MADE DRIVERS

(ANTHROPOGENIC)

Greenhouse gases

Some land use changes

Urbanization

Aerosols

The increase in the CO2 is predominantlybecause of burning fossil fuels

Causes of climate change

The greenhouse is a natural process mainly due to the effect of water vapor. The earth without the greenhouse effect would be 33oc 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: CO2, (CH4) , nitrogen oxide; CFC (chlorofluorocarbon).

Greenhouse effect

1. Average temperatures are likely to increase:

Africa as a whole, warming in the 20th 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

Climate change scenarios

Interaction between climate change &groundwater

Source: Taylor et al. (2013)

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.

Groundwater Recharge

Climate Change Impacts

Output component: Evapotranspiration, runoff, groundwater discharge into streams and springs and pumping

Drying up of springs, streams

Output

Climate Change Impacts

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 over-abstract renewable aquifers and hence depletion of storage.

High pumping rate results aquifer drying

Groundwater storageClimate Change Impacts

Soil salinization due to extreme evaporation

Flooding due to high rainfall and pollution from sanitation

Water qualityClimate Change Impacts

Expected changes as a result of climate change

Changes in precipitation frequency and intensity:

In addition to changes in global average precipitationthere could be more pronounced changes in thecharacteristics of regional and local precipitation due toglobal warming. On average, precipitation will tend tobe less frequent, but more intense, implying greaterincidence of extreme floods and droughts, withresulting consequences for water storage.

Expected changes as a result of climate change

Changes in average annual runoff:

-decreases in runoff due to higher temperatureswhich lead to higher evapotranspiration losses.

-increase runoff due to prolonged rainfall

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.

Climate Change and Population Growth

Most vulnerable rural communities

What is adaptation?

Adaptation is a process by whichindividuals, communities and countriesseek to cope with the consequences ofclimate 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.

Adaptation

Mitigate ... ... and adapt!Prevent

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.

Adaptation

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

Adaptation Options

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

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Managed Aquifer Recharge (MAR)