The Effect of Global Climate Change on Water Resourcestiffanyjebson.weebly.com/uploads/1/0/1/3/10137987/jebs…  · Web viewThe Effect of Global Climate Change on Water Resources.....Tiffany

The Effect of Global Climate Change on Water Resources............. Tiffany Jebson

Introduction

This chapter examines how water availability and quality may be affected by climate

change within the next century. Throughout this paper, five specific locations—the

western region of continental United States, The West Bank in the Middle East,

Tasmania, Bangladesh, and the Rhine River Basin—will be investigated in reference to

water quality and its capability of sustaining human life.

Freshwater is a necessity of human survival, and it is therefore important to

understand how global climate change might affect availability of water resources in the

future (EPA, 2009). As the global temperatures increases, concerns arise: water

availability may decrease as evaporation and transpiration increase, and human immune

system activity may slow as bacteria thrive in warm water (Justus, et al. 2006). This

paper addresses these concerns and other issues dealing with water sustainability and

water quality.

Water sustainability is the capability of water to support and maintain human life

(Weber. 2005). Water resources are already being overused and over-pumped. As

population increases problems with overuse may become worse. In this study, the effect

of climate change on water resources in several areas—the western region of continental

United States, The West Bank in the Middle East, Tasmania, Bangladesh, and the Rhine

River Basin—is examined. These locations were chosen due to their specific geography,

climates, and potential for climate change. For example, some areas of the western

United States obtain a large portion of freshwater from snowmelt (USGS. 2011). Figure 1

shows daily streamflow in the Northfork American River at North Fork Dam in

California in years 1998-2002. The high streamflow during the first part of each year is

thought to reflect snowmelt entering the river. During the years 1998-2001, it can be

interpreted that a large amount of snowfall occurred, thus resulting in a larger

streamflow. While a global temperature increase will initially promote more snowmelt,

temperature increase may limit the amount of future snowfall (USGS. 2011).

For the purpose of this study, water quality is defined by the physical, chemical,

and biological properties of water. More specifically, water quality describes the ability

of water to be ingested, to be applied agriculturally, and to be used by humans without

any harmful effects—long-term or short-term.

This paper will explain consequences and benefits of climate change in reference

to global water resources, and it will analyze specific areas in reference to their current

climate and how their water resources might change in response to changing climate.

Consequences of Climate Change on Water Supply

This section provides information about potential hazards and concerns regarding

the impact of climate change on the availability and quality of freshwater. For example,

when water quality is compromised, human health may be at risk; lack of freshwater in

the form of precipitation may diminish crop yield; and, higher temperatures cause algal

blooms, which may lead to areas of diminished oxygen. This section will deal

Figure 1. Hydrograph which shows daily mean streamflow (average streamflow for each day) for four years for the North Fork American River at North Fork Dam in California (USGS real-time streamflow data). http://ga.water.usgs.gov/edu/watercyclesnowmelt.html

specifically with issues concerning groundwater, weather patterns, algal blooms, hygiene,

and pollutants.

Groundwater: As climate change occurs, the water table, or the surface where the

water pressure is equal to the atmospheric pressure, may lower as a temperature increase

may cause clouds to retain more water. As the water table lowers to deeper levels,

drinking water wells must be drilled deeper in order to access the groundwater. This may

pose a problem as drilling deeper is more expensive and requires specialized equipment

not readily available in some areas. In addition, deeper drinking water wells may reduce

groundwater recharge. Groundwater recharge refers to the process of surface water

infiltrating the surface, moving downward, and reaching the level in which the

groundwater was before pumping.

Groundwater recharge can be induced by humans—for example, septic system

drain fields—or occur naturally via precipitation. A 15% reduction in precipitation has

been shown to drastically slow groundwater recharge by as much as 40-50% (Sandstrom,

1995).

Another issue, in addition to the reduction in recharge, is a potential increase in

groundwater discharge. Groundwater discharge is the process of water moving upward

from an aquifer to the surface or atmosphere. Similar to groundwater recharge, this

process occurs either artificially or naturally. Increased groundwater discharge can be

problematic, as it may cause a small rise in sea level due to the large amounts of water

stored in the ground being released and eventually ending up in the ocean (Sahagian et

al., 1994).

Figure 2. Groundwater recharge and infiltration.

http://www.wellaware.ca/pages/GroundWater.php

Sea level rise, due to either an increase in groundwater discharge or melting ice

caps, may affect approximately one quarter of the world’s population who live in a

coastal region. These regions contain only 10% of the global renewable water supply, and

an increase in high salinity water may diminish already-limited freshwater sources

(Kundzewicz et al., 2007). Figure 2 shows the cycle of groundwater recharge and

discharge via infiltration and percolation, or the movement of water through a medium.

Another concern pertaining to drilling deeper wells is that the salinity and

temperature of groundwater may increase, resulting in a lower quality of water. This is

called saltwater intrusion, the movement of saline water to bodies of freshwater.

Weather Patterns: An increase in temperature poses many concerns regarding the

availability of freshwater for human consumption and use. Climate change may

drastically alter precipitation patterns globally. For example, climate change may increase

rainfall in areas of northern latitudes and the tropics, while decreasing rainfall in areas of

lower–mid latitudes (CCSP, 2008). In 2011, Green et al. published a paper modeling the

global changes in mean annual precipitation, evaporation, soil water content, and runoff

for the years 2080–2099. It was estimated that precipitation over land would increase by

about 5%, and precipitation over the ocean would increase by approximately 4%. This

estimated increase in average rainfall was attributed to a proposed increase in water

availability within clouds as they increase in temperature (Green et al. 2011). Similarly,

average evaporation was projected to increase over the ocean with variations related to

surface warming. Over terrestrial

areas, rainfall changes tend to be

controlled by both

evapotranspiration (ET), a term

used to combine total evaporation

and transpiration, and runoff.

Evapotranspiration is illustrated in

Figure 3. For example, average

Figure 3. Diagram of Evapotranspiration. http://www.westone.wa.gov.au/toolbox6/hort6/html/resources/visitor_centre/fact_sheets/images/et.jpg

runoff will decrease in southern Europe and increase in Southeast Asia and areas with

high latitudes (Meehl, et al. 2007).

The increase in runoff may lead to higher soil moisture content as well as

unpredictable runoff patterns. As a result of this changing runoff, flooding may ensue.

Flooding may cause problems in overflowing sewer systems, releasing toxins into the

groundwater. Furthermore, some of these toxins may be bacterial in composition, and if

allowed to flow into surface water, eutrophication, a term describing excessive nutrient

content in water, may occur—promoting too much algae growth.

Algal Blooms: Warmer temperatures create an environment in which algae

thrives. Algal blooms will grow rapidly and deplete available oxygen in surface waters.

Areas where this occurs are known as “hypoxic zones” (Osterman, 2009). Hypoxic zones

occur in oxygen-depleted areas that are density stratified, usually thermally controlled,

and combined with a high amount of nutrients. Neither plant nor animal life can sustain

in hypoxic zones.

Algal blooms may also be responsible for compromising animal health, including

that of birds and fish. According to the World Health Organization, the most common

ways humans are affected by algal blooms are via drinking water and recreational

activities. For example, swimming in the vicinity of algal blooms may lead to accidental

ingestion. Side effects of accidental ingestion are vomiting, liver disease, blistering and

skin irritation.

Hygiene: An increase in poor hygiene is another factor that may become a

potential health hazard. Without clean water, viruses and many types of diseases may

Figure 4. Map of improved water sources. (WHO, 2008.)

spread rapidly. With the continual ingestion of contaminated water, immune system

activity slows. Weakened immune systems, caused by contaminated water, is responsible

for over two million child deaths each year (Prüss-Üstün, 2008). The World Health

Organization, in partnership with UNICEF Joint Monitoring Programme, estimates that

1.1 billion people do not currently have access to clean water. If freshwater becomes less

available due to climate change, more people may lose access. This is especially true in

areas that lack improved water sources, or water sources that are designed to provide safe

and useable water. Figure 4 shows the percentage of people per country that have access

to clean water. Countries with higher population growth, such as India and China, have

less access to improved water sources.

Pollutants: A pollutant is defined as a substance that is present in concentrations

that may harm living organisms or exceed an environmental quality standard. The term

is frequently used synonymously with contaminant. The United States Environmental

Protection Agency (USEPA) has put certain drinking water standards in place to inform

citizens about potential pollutants. Testing parameters include nitrogen, mercury, arsenic,

fecal coliform (E. Coli), and many other chemical and biological constituents. These

constituents are essential to the quality assurance of water, and if consumed in amounts

greater than the EPA standards, these pollutants may prove hazardous.

As the amount of available groundwater decreases due to soil evaporation,

pollutants that are already present in the water become more concentrated (Backlund et

al. 2008). Higher concentrations of unwanted chemical constituents may lead to lower

quality freshwater. In addition, using water of a different chemical composition will

affect applications in which the water can be used. For example, water with a high

salinity may only be used in industrial settings, as it is deemed non-potable. In addition,

high salinity waters have a higher density, which may limit use in steam-driven turbines

for the manufacturing of energy (Jonas. 1984).

While it is clear that climate change may have negative effects on water supply

and quality, in some cases climate change may improve the water supply and/or quality.

As temperature increases, especially in northern latitudes characterized by snow-covered

terrain, snowmelt may increase. Although a higher amount of snowmelt may increase the

chance of flooding, the excess runoff may provide more water to infiltrate groundwater

aquifers (Green et al. 2011). Groundwater is dominantly controlled by precipitation—

rather than by temperature—making it possibly less susceptible to climate change than

other water sources.

Some Specific Examples

Western United States: The climate in the western region of the United States

shown in yellow in Figure 5—is arid to semi-arid and in some particular places,

temperate. This portion of the U.S.

averages approximately 400mm of

annual precipitation;

however, this number does vary

significantly with elevation (CCPS, 2008).

Average precipitation in the Western U.S. is

relatively low compared to the eastern region,

which averages approximately 1100 mm of precipitation

annually.

Freshwater from this region

is mainly obtained from streams

that have been altered by reservoir management. Much of the runoff in this area is

directly sourced from snowmelt, which may be diminished with climate change.

Groundwater aquifers in this region are dependent on the type of geologic features

and rock types present. For example, in the eastern section of this area, the subsurface is

made up of sedimentary rocks. Generally, sedimentary rocks, such as sandstone and well-

jointed limestone, compose the most effective aquifers. Moving inland, the subsurface is

made up of igneous and metamorphic rocks, which have visible outcrops along the Rocky

Mountains. Igneous and metamorphic rocks are not usually great aquifers unless they are

faulted, which creates space for groundwater to occupy.

Mean annual precipitation in this area is predicted to decrease which could mean

less available water in this area. An increase in temperature may also lead to the earlier

melting of snow in the Rocky Mountains. Early spring streamflow of rivers in this area,

Figure 5. Map of Western Region of United States.http://www.mytowagent.com/images/map.gif

may increase due to the snowmelt and average summer streamflow may decrease. Areas

located along the coast may also be at risk for saltwater intrusion, an effect of lowering

water table and slower recharge rates (Bates et al. 2008).

The West Bank: The West Bank is located in the Middle East, near the

Mediterranean Sea, as shown by Figure 6. The landscape of the West Banks can be

divided into three distinct locations: the west, an area characterized by plains, the central

mountainous area, and the Jordan Rift valley in the east. The climate for this area is

temperate; temperature and precipitation vary with elevation, has warm to hot summers,

and cool to mild winters. Although there are

three distinct regions, climate change effects

will be averaged to create a single scenario for

The West Bank. Droughts are the

biggest natural disaster that affects the

West Bank and issues with sewage

treatment as well as adequacy of

freshwater are problematic.

Agriculture occupies 5% of cultivated

land but utilizes approximately 52% of

the available water resources (Mizyed.

2008). An estimated 2.3 million people

live in the West Bank. The expected

growth rate for the West Bank is

between three and four percent.

Freshwater is this area is obtained mostly from groundwater aquifers. Irrigation is

prevalent in this area due to lack of surface water.

The temperature increase in the West Bank is estimated to be from 1.7 to 6.5

degrees Celsius (Mizyed. 2008). From Mizyed, published in 2008, it is expected that an

increase in temperature may cause a six to seven percent increase in evapotranspiration.

The Sandstrom paper, published in 1995, estimates that this area may experience

approximately 16% loss in precipitation that could result in as much as a 30% decrease in

the groundwater recharge rate. With the location of the West Bank being in an area of

Figure 6. Map of the West Bank. http://israelipalestinian.procon.org/files/IsPal%20Images/westbank.jpg

political conflict, shortages in water may escalate existing tensions between different

extremist groups.

Tasmania, Australia: Located in the Pacific Ocean, shown by Figure 7, Tasmania

is an island approximately 240 km south of mainland Australia. Tasmania has a maritime

climate, meaning mild winters and warm summers with high annual rainfall.

Approximately 50% of Tasmania is native vegetation, 22% is forestry, 22% is grazing,

and 2% is irrigated agriculture (Post et al. 2012). The population is approximately

510,560 people and has a 0.33% growth

rate. Average rainfall for Tasmania is

approximately 1266mm annually.

However, there is a large discrepancy

between rainfall of the east and west

coasts of Tasmania. The west coast usually

receives approximately 4200mm of rain

annually, whereas the east coast receives

only 700mm (Post et al. 2012).

Using different models for climate change in Tasmania can yield very different

results. According to a paper written by Post et al. in 2012, there are three distinct models

used when predicting future water availability. The first model represents a wet climate

and predicts a 1% increase in precipitation and a 10% increase in groundwater recharge.

The second model, representing the median between wet and dry values, predicts a 2%

decrease in precipitation and yields current recharge rates. The final model, representing

a dry scenario predicts a 6% decrease in rainfall and a 5% decrease in groundwater

recharge. Runoff for each of these scenarios will be directly related to the amount of

annual precipitation, increasing with precipitation.

Bangladesh: Bangladesh lies between India and Burma shown on Figure 8 in red.

A humid, warm, tropical climate is characteristic of Bangladesh and is primarily

influenced by monsoon cycles. Monsoon cycles are dependent upon wind circulation; air

Figure 7. Map of Tasmania. http://media.web.britannica.com/eb-media/58/64358-004-54829D52.gif

rising over heated land in summer months creates a

low-pressure system then, comes in contact with a

cooler air mass that condenses warm air, thus creating

heavy rainfall. Bangladesh is used agriculturally and

approximately 85% of its population depends on these

agriculture activities. Bangladesh is characterized by

flat plains with occasional hills. Topography as well

as geographic location make Bangladesh prone to

natural disasters such as cyclones, flooding, erosion,

tornadoes, droughts, and earthquakes (Agrawala et al.

2003). Approximately 151,000,000 people live in

Bangladesh with a 2% growth rate (CIA World

Factbook. 2012).

A majority of freshwater for agriculture comes from tube wells. Tube wells are

essentially what is used in the United States as groundwater monitoring wells at landfill

sites. A schematic diagram of a tube well is illustrated in Figure 9. Tube wells are lined

with a polyvinyl chloride (PVC) pipe and have a screened interval at the bottom portion

of the well. Gravel and a type of clay called Bentonite line the well as a natural screen

and deterrent for large particles. When a well is installed, it needs to be developed. This

means that water must be purged from the well until it is clear. Since the well was not

dewatered during installation it may contain sediment and other particulate matter.

Hossain et al. published in 2011, uses current water table data and trends to model

future water availability. Depth to water table

may double around the year 2060. This will

increase pumping costs and environmental

problems may arise, which is common for

deeper drilled water wells. Overuse of

groundwater is occurring and pumping has

already surpassed the recharge rate, therefore

lowering the water table indefinitely.

Figure 9. Schematic Diagram of Tube Well. http://www.fhwa.dot.gov/bridge/tunnel/pubs/nhi09010/images/fig_15_29.gif

Figure 8. Map of Bangladesh. http://world.unomaha.edu/files/Image/cropped%20bangladesh_map.jpg

According to Agrawala et al. 2003, cyclone frequency is modeled. Peak

intensities of cyclones are predicted to increase by 5-10% and precipitation is expected to

increase by about 20-30%. This will increase the risk for flooding, which Bangladesh is

already prone to. Another risk for Bangladesh is sea level rise. Bangladesh is a low-lying

country and any changes to sea level will greatly affect Bangaladesh. Furthermore,

saltwater intrusion may also be another imminent threat.

Rhine River Basin, Europe: The Rhine River, located in Western Europe, is

shown in Figure 10. The Rhine River flows through seven countries and is essential for

hydropower generation, agriculture, industry, and domestic water use. The Rhine River

Basin is highly populated with

many large cities dependent upon

it.

The Rhine River starts in

the Swiss Alps and flows

downstream towards the low-lying

Netherlands. Many dams are built

along the Rhine River and the swift

current allows for rapid erosion.

When the river reaches the

Netherlands, the water begins to

slow, creating an environment that

allows rapid sedimentation, or the settling of sediment that was suspended (Middelkoop

et al. 2001).

Effects from climate change vary along this vast river basin. Middelkoop et al.,

published in 2001, identify the effects on the Rhine River from climate change. In the

alpine region of Switzerland, snow accumulation during the winter months will decrease

which will increase the amount of runoff. Warmer temperatures during the summer will

increase evaporation. With this increase in evaporation, this region may experience a

decrease in net runoff water. In the German-middle mountains area, evapotranspiration

along with precipitation determine the water availability. Evapotranspiration is estimated

to overcompensate the increase in annual precipitation, therefore giving this area a net

Figure 10. Map of the Rhine River Valley. http://3.bp.blogspot.com/_A0lijzs4VO4/TJBVwVN7_tI/AAAAAAAAAK0/BnOdweLIrbQ/s1600/Rhine+River.jpg

decrease in runoff water. Finally, in the lowland area of the Rhine River Basin,

streamflow is estimated to increase by approximately 20% due to an increase in

precipitation. During the summer months, evaporation will take up a large portion of

water, possibly causing a water deficit for a given amount of time during the summer.

Conclusion

Using mathematical models and present examples, water sustainability due to

climate change can be investigated. Advancing technology, to more efficiently clean and

distribute freshwater, needs to continue in order to keep up with the growing demand of

clean water. By reducing greenhouse gas emissions and humankind’s carbon footprint,

the adverse effects of climate change may be impeded. More efficient water management

programs need to be initiated. By looking at specific examples, effects on water resources

from climate change can be better understood. The only thing that is certain is that water

is vital and without it, life will not continue.

Bibliography

American Society for Testing and Materials. (1991) Annual Book of ASTM Standards.

Designation: D5092-90 Standard Practice for Design and Installation of

Groundwater Monitoring Wells in Aquifers.1081-1092.

CIA. (2012) Central Intelligence Agency: Bangladesh. The World Factbook.

https://www.cia.gov/library/publications/the-world-factbook/geos/bg.html

Congressional Research Service (2006) Global Climate Change. CRS Issue Brief for

Congress. Received through the CRS Web.

http://fpc.state.gov/documents/organization/67128.pdf

CORROSION. (1984) Steam turbine corrosion.

http://www.steamcycle.com/steam_turbine_corrosion.pdf

Emori, S., and S. J. Brown. (2005) Dynamic and thermodynamic changes in mean and

extreme precipitation under changed climate, Geophys. Res. Lett., 32

Green, T., Taniguchi, M., Kooi, H., Gurdak, J., Allen, D., Hiscock, K., Treidel, H.,

Aureli, A. (2011) Beneath the surface of global change: Impact of climate change

on groundwater. Journal of Hydrology, 405, 532-560.

Hossain, A., Abustan, I., Rahman, A., Haque, A. (2011) Sustainability of Groundwater

Resources in the North-Eastern Region of Bangladesh. Water Resources

Management, 26, 623-641.

IPCC (2007) Global Climate Projections. In: Climate Change 2007: The Physical Science

Basis. Contribution of Working Group I to the Fourth Assessment Report of the

Intergovernmental Panel on Climate Change.

http://www.cgd.ucar.edu/ccr/knutti/papers/AR4WG1_Pub_Ch10.pdf

IPCC (2008) Climate Change and Water. Technical Paper of the Intergovernmental Panel

on Climate Change. http://www.ipcc.ch/pdf/technical-papers/climate-change-

water-en.pdf

Middelkoop, H., Daamen, K., Gellens, D., Grabs, W., Kwadijk, J., Lang, H., Parmet, B.,

Schadler, B., Schulla, J., Wilke, K. (2001) Impact of Climate Change on

Hydrological Regimes and Water Resources Management in the Rhine Basin.

Climatic Change, 49, 105–128.

Mizyed, N. (2008) Impacts of Climate Change on Water Resources Availability and

Agricultural Water Demand in the West Bank. Springer Science, October 31.

Published Online.

Organization for Economic Co-operation and Development (2003) Development and

climate change in Bangladesh: Focus on coastal flooding and the sundarbans.

http://www.oecd.org/dataoecd/46/55/21055658.pdf.

Osterman, L., Poore, R., Swarzenski, P., Senn, D., DiMarco, S. (2009) The 20th-century

development and expansion of Louisiana shelf hypoxia, Gulf of Mexico. Geo-

Marine Letters. 29, 405-414.

P. Backlund, A. Janetos, D. Schimel, J. Hatfield, K. Boote, P. Fay, L. Hahn, C.

Izaurralde, B.A. Kimball, T. Mader, J. Morgan, D. Ort, W. Polley, A. Thomson,

D. Wolfe, M.G. Ryan, S.R. Archer, R. Birdsey, C. Dahm, L. Heath, J. Hicke, D.

Hollinger, T. Huxman, G. Okin, R. Oren, J. Randerson, W. Schlesinger, D.

Lettenmaier, D. Major, L. Poff, S. Running, L. Hansen, D. Inouye, B.P. Kelly, L.

Meyerson, B. Peterson, R. Shaw. (2008) The effects of climate change on

agriculture, land resources, water resources, and biodiversity in the United

States. A Report by the U.S. Climate Change Science Program and the

Subcommittee on Global Change Research. U.S. Department of Agriculture,

Washington, DC, USA. 362, 1-242.

Post, D., Chiew, F., Teng, J., Viney, N., Ling, F., Harrington, G., Crosbie, R., Graham,

B., Marvanek, S., McLoughlin, R. (2012) A robust methodology for conducting

large-scale assessments of current and future water availability and use: A case

study in Tasmania, Australia. Journal of Hydrology, 412-413, 233-245.

Sahagian, D., Schwartz, F., and Jacobs, D. (1994) Direct anthropogenic contributions to

sea level rise in the twentieth century. Nature (London), 367, 54-57.

Sandstrom, K. (1995) Modeling the effects of rainfall variability on groundwater

recharge in semi-arid Tanzania. Nordic Hydrology, 26, 313-330. 

United States Geological Survey. February 25, 2012. The Water Cycle: Snowmelt

Runoff. http://ga.water.usgs.gov/edu/watercyclesnowmelt.html

Weber, W. (2006) Distributed optimal technology networks: an integrated concept for

water reuse. Desalination, 188, 163-168.

World Health Organization. (2008) Safer water, better health: costs, benefits and

sustainability of interventions to protect and promote health.

http://whqlibdoc.who.int/publications/2008/9789241596435_eng.pdf

World Health Organization. (2012) Water-related diseases.

http://www.who.int/water_sanitation_health/diseases/cyanobacteria/en/