CLIMATE change affects the components of water cycle such as evaporation, precipitation and evapotranspiration and thus results in large-scale alteration in water present in glaciers, rivers, lakes, oceans, etc. The effects of cli-mate change on subsurface water relates to the changes in its recharge and discharge rates plus changes in quantity and quality of water in aquifers. Climate change refers to the long-term changes in the components of climate such as temperature, precipitation, evapotranspiration, etc. The major cause of climate change is the rising level of greenhouse gases (GHGs) in the atmosphere such as CO2, CH4, N2O, water vapour, ozone and chlorofluorocarbon. These GHGs absorb 95% of the longwave back radiations emitted from the surface, thus making the Earth warmer. Except CO2, the effects of other GHGs are minor because of their low concentration and also because of low residence times (e.g. water vapour and methane). The rise in CO2 level causing global warming was first proposed by Svante Arrhenius, a Swedish scientist in 1896 and now it is a widely accepted fact that the concentration of CO2 is the primary regulator of temperature on the Earth and leads to global warming.

1. Presented by;
Abhishek Kumar
414ER2018
Earth & Atmospheric Sciences
IMPACT OF CLIMATE CHANGE ON
GROUNDWATER
abhi.gly@gmail.com

2. o Groundwater in Hydrologic cycle
o What is Climate Changes?
o Hydrological Impact of Climate change
o Impact of Climate Change On Groundwater
o Climate change Scenario for Groundwater in India
o Methodology to Assess the Impact of climate Change On
Groundwater
PRESENTATION OVERVIEW

3. WHY INCLUDE GROUNDWATER IN CLIMATE CHANGES
STUDIES?
o Although groundwater accounts for small
percentage of Earth’s total water,
o Groundwater comprises approximately thirty
percent of the Earth’s freshwater.
o Groundwater is the primary source of water
for over 1.5 billion people worldwide.
o Depletion of groundwater may be the most
substantial threat to irrigated agriculture.

4. Natural groundwater recharge
accounts for:
Components of the hydrologic cycle:
Precipitation, Evaporation,
Transpiration, Recharge,
And Baseflow.
Heterogeneity of geological
structures, local vegetation, and
weather condition
“NATURAL” GROUNDWATER RECHARGE

5. oGroundwater overdraft / mining / subsidence
oWaterlogging
oSeawater intrusion
oGroundwater pollution
PROBLEMS WITH GROUNDWATER

6. o Hazardous industrial waste
o Leachate from landfills
o Agricultural activities such ac the use of fertilizer and pesticides
o The total volume that may be withdrawn annually from the aquifer.
o The location of pumping and artificial recharge wells, and their rates.
o Decisions related to groundwater quality.
Management of a groundwater system, means making such
decisions as:
Groundwater contamination by:

7. IPCC usage:
-Any change in climate over time, whether due to natural
variability or from human activity.
Alternate:
-Change of climate, attributed directly or indirectly to human
activity, that
-Alters composition to global atmosphere
and
-Is in addition to natural climate variability
observed over comparable time periods
WHAT IS CLIMATE CHANGE?

8. Both natural and anthropogenic factors
control climate change .
climatic conditions were not the same
throughout the history of the Earth.
Natural causes:
Earth’s axial and orbital changes
changes in the strength of the Sun
plate movements
asteroid collision and chemical
weathering
FACTORS CAUSING CLIMATE CHANGE
Climatic fluctuations all through the geological timescale

9. Earth’s axial and orbital changes
o The change in the tilt of the axis of the Earth affects the
amount of solar radiation received on the surface
o it shows a latitudinal difference and thus results in
seasons on Earth
o The Earth’s axial tilt at present is 23.5⁰ and varies
between 22.2⁰ and 24.5⁰.
o Increase in the tilt amplifies seasonal differences and
decrease in the tilt results in the reduction of
seasonal differences and thus affects Earth’s climate.
Changes in the strength of the Sun:
o The strength of the Sun is measured by the number of
sunspots visible on its surface
o The concentration of CO2 decreases with the cooling
of oceans and increases with their heating, proving
that the Sun is a primary driver of climate on Earth.
Plate tectonics:
o The position of south magnetic pole during 430 m.y. ago
coincides with the climate change that has been
observed, which showed the occurrence of large-scale
glaciations in the modern-day Sahara Desert .
o Volcanic eruptions also change the composition of the
atmosphere by ejecting SO2, CO2, water vapour and
pyroclastic materials .

10. Asteroid collision:
o large-sized (greater than 10 km radius) impacts are rare
and arrive on the Earth only after every 50–100 million
years.
o The Earth has experienced such events during the
Permian–Triassic boundary and at the Cretaceous–
Tertiary boundary which resulted in mass extinctions and
in the beginning of a new era
Chemical weathering:
o The changes in CO2 concentration in the atmosphere can
be related to the chemical weathering processes, which
include hydrolysis and dissolution.

11. Groundwater is directly affected by changes in the
rate of precipitation and evapotranspiration.
The response of groundwater to climate change
may be less compared to surface water, however, it
is still a matter of concern because groundwater is
one of the largest available resources of freshwater
and potable water on Earth.
It is estimated that approximately 30% of global
freshwater is present in the form of groundwater.
Todd divided the groundwater occurrence in two
zones – zone of aeration and zone of saturation.
The effect of climate change on both the zones has
been discussed in the following
Zone of aeration
Soil water zone
Vadose zone
Zone of saturation
EFFECT OF CLIMATE CHANGE ON GROUNDWATER ZONES

12. Soil water zone:
o This zone is important as it supports vegetation and all
biogeochemical reactions. Climate change has an adverse effect
on this zone.
o Higher temperature leads to higher evapotranspiration rates,
resulting in less moisture content in this zone. Little or no moisture
in the soil leads the penetration of solar radiation into the deeper
soils and increased dryness in soils, resulting in severe droughts .
o The high precipitation in wet climate change scenario will increase
surface run-off and in promoting rapid soil erosion.
o Less infiltration, high evapotranspiration and high run-off will have
a great impact on the water availability in this zone, which will
affect the entire plant and animal kingdom.
o Because of change in evapotranspiration patterns in this zone, the
rainfall pattern will also be affected. The transpiration process
which holds 80–90% of overall evapotranspiration on Earth will
show various changes depending on the regional vegetation.
ZONE OF AERATION

13. Vadose zone:
o Changes in vadose zone due to climate change can be
computed by studying the variations in major cations, an-
ions, trace elements and isotopes from the pore water.
o Due to increase in surface temperature, groundwater
temperature will increase. The change in temperature will
affect pore water chemistry, residence time and volume of
water in matrix and fractures, and thus the composition of
the water.
o The increase in recharge rate will help in mobilizing the
contaminants into greater depths. As an example, in
semiarid and arid regions, increased infiltration can
mobilize large, pore-water chloride and nitrate reservoirs
affecting the quality of water.
o The diurnal temperature fluctuations may be detectable at
depths of less than 1 m in the unsaturated zone and
seasonal fluctuations at depths of 10 m or more, indicating
that that the climate change effects depend on depth
and are slow in the deep vadose zone.
ZONE OF AERATION

14. o Groundwater in the saturated zone is
important as it is less polluted and has no
effects of evapotranspiration.
o The sensitivity of this zone depends on the
depth of the water table; shallow aquifers
are more vulnerable to cli-mate change
than deeper aquifers.
o This zone responds to climate change by
showing changes in its amount, quality and
flow of water depending on the trends of
precipitation, evapotranspiration, recharge
and discharge.
o It is generally observed that climate change
has less effect on this zone in comparison
to human activities on groundwater
exploitation, such as excessive
pumping, reduction in recharge rate and
contamination.
ZONE OF SATURATION

15. o Confined and unconfined will show
alterations in some of their properties during
climate change. It has been noticed that
severe dry periods can alter the properties of
aquifers such as transmissivity and
storativity.
o During dry periods, the conductive channels
such as fractures and fissures may become
desaturated and the pressure pulse of water
within the aquifer will be transmitted slowly,
whereas during the wet season, fractures
get fully saturated and transmit pressure
pulse rapidly. Thus, the changes in recharge
pattern will affect the specific storage of an
aquifer.
o In case of extreme aridity, their vulnerability
becomes higher if the potentiometric surface
falls below the upper confining beds and
results in converting confined aquifers to
unconfined aquifers.
EFFECT OF CLIMATE CHANGE ON AQUIFERS

16. Groundwater Recharge:
o The changes in recharge patterns will affect
discharge patterns, which will have a direct impact
on groundwater supplies and on surface water
availability.
o In a cold or wet and cold–wet scenario, the
relationship is directly proportion-al, i.e. high
temperature results in high precipitation and high
recharge.
o In case of dry scenario, the temperature and
precipitation are inversely related to each other, as
high temperature will result in less rainfall. Hence,
the effects in case of dry scenario will be severe,
implying that the aquifers of semiarid and arid
regions are more vulnerable to climate change.
o Changes in recharge patterns will also alter the
quality of water by affecting geochemical reactions
and movement of water in the vadose zone.
o Various types of aquifers will be recharged
differently. The main types are unconfined and
confined aquifers.
EFFECT OF CLIMATE CHANGE ON RECHARGE AND DISCHARGE

17. Groundwater Recharge:
o An unconfined aquifer is recharged directly by local
rainfall, rivers, and lakes, and the rate of recharge will
be influenced by the permeability of overlying rocks and
soils.
o Unconfined aquifers are sensitive to local climate
change, abstraction, and seawater intrusion. However,
quantification of recharge is complicated by the
characteristics of the aquifers themselves as well as
overlying rocks and soils.
o A confined aquifer, on the other hand, is characterized
by an overlying bed that is impermeable, and local
rainfall does not influence the aquifer. It is normally
recharged from lakes, rivers, and rainfall that may occur
at distances ranging from a few kilometers to thousands
of kilometers.
o Determining the potential impact of climate change on
groundwater resources, in particular, is difficult due to
the complexity of the recharge process, and the
variation of recharge within and between different
climatic zones.
DISCHARGE

18. Groudnwater Discharge:
o Under wet climate scenarios, run-off is considered as a most
sensitive component and the combined effect of in-creased
precipitation and high discharge will increase the risk of flooding.
o Under dry climate scenarios, recharge will be the most sensitive
component as evapotranspiration will increase while both
recharge and discharge will decrease in all seasons, resulting in
decline in ground-water level.
o Increased discharge from melting of glaciers in the Himalayas
will increase the risk of flooding in the catchment areas affecting
major parts of North India, Pakistan and Bangladesh.
o Due to changes in discharge, the quality of groundwater will be
adversely affected, since during high discharge all the pollutants
will be mobilized and may reach groundwater level.
o In the case of a dry climate scenario, generally the water level
will fall and this will affect the needs of the people and may
result in increased use of energy to ex-tract water.
o The increase in groundwater pumping and loss of groundwater
storage from aquifers resulted in land subsidence in many Asian
cities such as Osaka and Bangkok. In future, the increase in dis-
charge and decrease in recharge will make land subsidence a
much bigger problem
EFFECT OF CLIMATE CHANGE ON RECHARGE AND DISCHARGE

19. o The groundwater quality relates to the physical, chemical and biological
properties of the aquifers, which are controlled by climatic fluctuations.
o changes in the recharge rate and the groundwater temperature in the
vadose zone affect its pore water chemistry, contaminant transport and
residence time, thus affecting the quality of water.
o Under a climate change scenario, the following events can deteriorate the
groundwater quality. During the wet scenario, increased infiltration can
mobilize large pore-water chloride and nitrate reservoirs in the vadose zone
of semiarid and arid regions.
o Increase in recharge leads to the dissolution of carbonates; increase in Ca
content may increase the hardness of groundwater.
o During a dry scenario, the increase in total dissolved solids may deteriorate
the groundwater quality by increased salt content
EFFECTS OF CLIMATE CHANGE ON GROUNDWATER QUALITY

20. The three major reasons for the sea-level
rise are: expansion of oceans on warming,
increase in discharge due to melting of
glaciers and excessive pumping due to
human settlements along the coasts.
The rise in sea level is said to have a great
impact on the man-grove forests of the
world and aquatic life, affecting the fish
stocks and planktons1,28. It is estimated
that 30% of coral reefs could be lost in the
next 10 years, which will affect the food web
of the aquatic environment.
EFFECT OF CLIMATE CHANGE ON SEA-WATER INTRUSION

21. India’s groundwater status and
utilization
o India accounts for 2.45% of land area and
16% of the world population, whereas
only 4% of freshwater re-sources of the
world are available in India, of which
38.5% is groundwater.
o India was utilizing less groundwater
compared to USA and Europe, but by
2000, India utilized around 220–230
billion m3 year-1, over twice that the USA
.
o The per capita water availability is
continuously declining from 5176 m3 in
1951 to 1820 m3 as on 1 March 2001 and
1703.6 m3 on 1 March 2005.
EFFECT OF CLIMATE CHANGE ON
GROUNDWATER RESOURCES OF INDIA

22. Climate change effect on Indian groundwater resources
o The levels are continuously falling down. Groundwater level in Gujarat,
Rajasthan, Punjab, Haryana and Tamil Nadu has shown a critical decline.
o Groundwater decline has been registered in 289 districts of India. The water
table in Ahmedabad is falling at a rate of 4–5 m every year; in some parts of
Delhi a lowering of 10 m has been noticed.
o Due to melting of the Himalayan glaciers, the Indo-Gangetic Plains will
experience increased water dis-charge till 2030s but will face gradual
reductions thereafter.
o Sea-water intrusion has been observed in several coastal states of India, such
as Tamil Nadu, Puducherry and Gujarat (Saurashtra), which is not only
engulfing the land but also the groundwater reservoirs
o India is highly sensitive to climate change in terms of its effect on water supply
for irrigation needs.
EFFECT OF CLIMATE CHANGE ON
GROUNDWATER RESOURCES OF INDIA

23. Behavioural and structural adaptations:
o using buckets and not showers for bathing and use of recycled water for agriculture.
o Structural adaptation implies building infrastructure or techniques that can minimize
the risk of climate change on groundwater and increase storage capacity of aquifers.
o rainwater harvesting, artificial recharge of aquifers, underground dams, reservoirs
and check dams, etc.
Defining groundwater risk zones and climate change mapping:
o Spatiotemporal effect of climate change on aquifers should be assessed and based
on this risk assessment of each aquifer should be rated and actions and policies
should be designed accordingly.
o Climate change mapping on different resources will give better results and answers
about the vulnerability and risks involved over time for a specific area
MITIGATION STRATEGIES TO REDUCE
EFFECTS OF CLIMATE CHANGE

24. Promoting afforestation:
o Trees are the sinks for CO2 on the Earth, and to minimize the effect of global warming,
afforestation is the best way, with the aim of reducing deforestation.
o Land-use development planning should emphasize on planting more trees and
increasing recharge area.
CO2 sequestration:
o Due to unusually large amounts of CO2 added to the atmosphere, carbon cycle is
insufficient to maintain the balance.
o annual carbon emissions from the use of fossil fuels in USA accounts for 1.6 giga tons,
whereas the natural annual uptake is only about 0.5 giga tons, i.e. 1.1 giga tons per
year remains in the atmosphere.
o This extra CO is responsible for global warming, which can be trapped in forests,
grasslands, oceans and in the sedimentary formations such as coals.
o this sequestration processes is also beset with many environmental issues and
concerns
MITIGATION STRATEGIES TO REDUCE
EFFECTS OF CLIMATE CHANGE

25. Bouraoui et al. (1999)
o Presented a general approach to evaluate the effect of potential
climate changes on groundwater resources.
o A general methodology is proposed in order to disaggregate outputs
of large-scale models and thus to make information directly usable
by hydrologic models.
o Two important hydrological variables: rainfall and potential
evapotranspiration are generated and then used by coupling with a
physically based hydrological model to estimate the effects of
climate changes on groundwater recharge and soil moisture in the
root zone.
STATUS OF RESEARCH & CASE STUDIES

26. Sherif and Singh (1999)
o Investigated the possible effect of climate change on sea water intrusion
in coastal aquifers.
o Using two coastal aquifers, one in Egypt and the other in India, this
study investigated the effect of likely climate change on sea water
intrusion.
o Under conditions of climate change, the sea water levels will rise which
will impose additional saline water heads at the sea side and therefore
more sea water intrusion is anticipated.
o A 50 cm rise in the Mediterranean sea level will cause additional
intrusion of 9.0 km in the Nile Delta aquifer.
o The same rise in water level in the Bay of Bengal will cause anadditional
intrusion of 0.4 km
STATUS OF RESEARCH & CASE STUDIES

27. Ghosh Bobba (2002)
o Analysed the effects of human activities and sea-level changes on
the spatial and temporal behaviour of the coupled mechanism of
salt-water and freshwater flow through the Godavari Delta of India.
o The density driven salt-water intrusion process was simulated with
the use of SUTRA (Saturated-Unsaturated TRAnsport) model.
o The results indicate that a considerable advance in seawater
intrusion can be expected in the coastal aquifer if current rates of
groundwater exploitation continue and an important part of the
freshwater from the river is diverted for irrigation, industrial and
domestic purposes.
STATUS OF RESEARCH & CASE STUDIES

28. Brouyere et al. (2004)
o Developed an integrated hydrological model (MOHISE) in order to
study the impact of climate change on the hydrological cycle in
representative water basins in Belgium.
o This model considers most hydrological processes in a physically
consistent way, more particularly groundwater flows which are
modelled using a spatially distributed, finite-element approach.
o The groundwater model is described in detail and results are
discussed in terms of climate change impact on the evolution of
groundwater levels and groundwater reserves.
o Most tested scenarios predicted a decrease in groundwater levels in
relation to variations in climatic conditions.
STATUS OF RESEARCH & CASE STUDIES

29. Holman (2006)
o Described an integrated approach to assess the regional impacts of
climate and socio-economic change on groundwater recharge from East
Anglia, UK.
o Important sources of uncertainty and shortcomings in recharge
estimation were discussed in the light of the results.
o Changes to soil properties are occurring over a range of time scales,
such that the soils of the future may not have the same infiltration
properties as existing soils.
o The potential implications involved in assuming unchanging soil
properties were described.
STATUS OF RESEARCH & CASE STUDIES

30. Mall et al. (2006)
o Examined the potential for sustainable development of surface water and
groundwater resources within the constraints imposed by climate change
and future research needs in India.
o He concluded that the Indian region is highly sensitive to climate change.
o The National Environment Policy (2004) also advocated that
anthropogenic climate changes have severe adverse impacts on India’s
precipitation patterns, ecosystems, agricultural potential, forests, water
resources, coastal and marine resources.
o Large-scale planning would be clearly required for adaptation measures
for climate change impacts, if catastrophic human misery is to be
avoided.
STATUS OF RESEARCH & CASE STUDIES

31. Ranjan et al. (2006)
o Evaluated the impacts of climate change on fresh groundwater
resources specifically salinity intrusion in five selected water resources
stressed coastal aquifers.
o The annual fresh groundwater resources losses indicated an increasing
long-term trend in all stressed areas, except in the northern
Africa/Sahara region.
o They also found that precipitation and temperature individually did not
show good correlations with fresh groundwater loss.
o They also discussed the impacts of loss of fresh groundwater resources
on socio-economic activities, mainly population growth and per capita
fresh groundwater resources.
STATUS OF RESEARCH & CASE STUDIES

32. Toews (2007)
o Modeled the impacts of future predicted climate change on groundwater
recharge for the arid to semi-arid south Okanagan region, British
Columbia.
o Climate change effects on recharge were investigated using
stochastically-generated climate from three GCMs.
o Spatial recharge was modelled using available soil and climate data
with the HELP 3.80D hydrology model.
o A transient MODFLOW groundwater model simulated rise of water table
in future time periods, which is largely driven by irrigation application
increases.
STATUS OF RESEARCH & CASE STUDIES

33. o These studies are still at infancy and more data, in terms of field
information, are to be generated. This will also facilitate appropriate
validation of the simulation for the present scenarios.
o In summary, climate change is likely to have an impact on future
recharge rates and hence on the underlying groundwater resources.
The impact may not necessarily be a negative one, as evidence by
some of the investigation.
o Quantifying the impact is difficult, and is uncertainties present in the
future climate predication.
o However, it is clear that the global warming threat is real and the
consequences of climate change phenomena are many and alarming.
CONCLUDING REMARKS ON THE RESEARCH STUDIES

34. The methodology consists of three main steps.
1. To begin with, climate scenarios can be formulated for the future years such as 2050
and 2100.
2. Secondly, based on these scenarios and present situation, seasonal and annual
recharge are simulated with the UnSat Suite (HELP module for recharge) or Wet
Spass model.
3. Finally, the annual recharge outputs from UnSat Suite or Wet Spass model are used
to simulate groundwater system conditions using steady-state groundwater model
setups, such as MODFLOW, for the present condition and for the future years
METHODOLOGY TO ASSESS THE IMPACT OF CLIMATE CHANGE ON
GROUNDWATER RESOURCES

35. The influence of climate changes on groundwater levels and salinity, due to:
a. Sea level rise
b. Changes in precipitation and temperature
Methodology
1. Develop and calibrate a density-dependent numerical groundwater flow model
that matches hydraulic head and concentration distributions in the aquifer.
2. Estimate changes in sea level, temperature and precipitation downscaled from
GCM outputs.
3. Estimate changes in groundwater recharge.
4. Apply sea level rise and changes in recharge to numerical groundwater model
and make predictions for changes in groundwater levels and salinity distribution.
METHODOLOGY TO ASSESS THE IMPACT OF CLIMATE CHANGE ON
GROUNDWATER RESOURCES

36. oDivide the globe into large
size grids
oPhysical equations
oLots of computing
oPredict the climatological
variables
GLOBAL CLIMATE MODELS (GCM)

37. Five step process outline by Glieck & Frederick (1999)
o Look at several Global Climates Models (GCMs) and look for
consensus & ranges
o Downscale to level needed (statistical and dynamical
methods)
o Apply impact ranges to hydrologic modeling
o Develop systems simulation models
o Assessment of the result (historic and GCMs) at
representative time frames
GLOBAL CLIMATE MODELS TRANSLATED TO
LOCAL IMPACTS

38. o Threats:- quality and quantity of the groundwater resources.
o GHGs:-its effect on continental surface water, oceans, ocean
productivity, vegetation, etc. In addition, it has a significant effect on the
energy cycle and groundwater.
o We perceive the immediate climate change effects in terms of floods,
drought conditions, glacial melts, etc. The effect of climate change is
significantly more on the semiarid, arid and coastal aquifers of the
world.
o In India, the vulnerability is extremely high because of overexploitation
of the groundwater and accompanied land subsidence in urbanized
areas.
o Groundwater is one of the most utilized resources in India for drinking
and irrigation purposes. better planning and management of this vital
resource.
CONCLUSION

39.  IPCC, Climate Change 2007 Synthesis Report, An Assessment of the
Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge,
UK, 2007, p. 73.
 Global warming, 2010; http://earthobservatory.nasa.gov
 Frederick, K., Climate Issues, Brief No. 3, Water Resources and Climate Change.
Resource for the Future, 1997, pp. 1–11.
 Todd, K. D., Groundwater Hydrology, John Wiley, New York, 1980, 2nd edn, p. 527.
 Singh, R. D. and Kumar, C. P., Impact of climate change on groundwater resources,
2010; www.angelfire.com/nh/cpkumar/ publication
 Kumar, R., Singh, R. D. and Sharma, K. D., Water resources of India. Curr. Sci., 2005,
89, 794–811.
 Climate change policies in the Asia-Pacific, re-uniting climate change and sustainable
development. IGES, 2008, pp. 159–180.
 Carbon sequestration to mitigate climate change, 2008; www. usgs.gov
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