Penn StateNASA

Module 8: Water Resources and Climate Change

Introduction

There is a new generation of super-rich and highly influential people who are starting to really invest massive amounts of money and influence in truly important causes. Bill and Melinda Gates in global health, Warren Buffett in reproductive health and food, the Jolie-Pitts in community development and the Katrina recovery effort. Now enter Matt Damon and Gary White who have co-founded water.org, an organization dedicated to developing and delivering solutions to the global water crisis. Visit the Water.org website and you will find an impressive array of information and programs. Here are direct facts from that site which convey the magnitude of the current global water emergency.

  • Nearly 1 billion people are living without accessible water
  • 2.5 billion without adequate sanitation
  • 440 million school days lost
  • 220 million hours each day are spent collecting water
  • 3.7 miles walked each day by women and children
  • 4100 children under five die each day from preventable water-related illness
  • 3.4 million people die each year from preventable water-related disease

More than any other resource, with the exception of food, water is crucial for human survival. Ancient civilizations were repeatedly forced to deal with the threat of diminishing water supply. Now, climate change presents a new threat by causing the supply and distribution of water to change over coming decades and centuries. This situation will be made significantly more dire by explosive population growth in parts of the world where water is scarce and by pollution that will continually limit the supply of clean drinking water. The IPCC (2007) stated the situation very clearly: “Water and its availability and quality, will be the main pressures on, and issues for, societies and the environment under climate change.”

Because groundwater systems recover very slowly from human impacts, remediation can be extremely difficult and expensive. In this module we begin by examining the distribution and behavior of water close to the Earth’s surface; next we consider how climate change will alter the supply of water and how population growth will change the demand. Finally, we present management strategies that will hopefully preserve the supply of water for humans around the globe.

Ancient civilizations developed in some of the driest realms of the planet. Populations in Egypt and Mesopotamia (an area that includes parts of modern Iran, Iraq, Syria and Turkey) learned how to survive in an arid environment. For example, ancient Egyptians and Mesopotamians constructed an extensive network of canals to transport water away from the Nile River for irrigation. Shadufs, which are contraptions consisting of buckets at the end of a boom which could be lowered with a rope, were used to haul water out of the canals and onto the fields. These civilizations routinely had to live with highly irregular precipitation consisting of periods when large amounts of rainfall flowed through the canals and flooded large areas, alternating with times of almost no rainfall.

Examples of Ancient Civilizations

Satellite image of the Nile river valley and delta region in Egypt Irrigation in the Nile River valley Person using a Shaduf to extract water from the Nile River

Click the images above to see full size images and to see complete source information.

As population has increased, and, especially with the rise of industry in developed nations, so has demand for water soared. Moreover, industry has increased competition often for the cleanest drinking water supplies.

Nowhere has the interplay between increasing demand and limited supply of water been more complicated than in the desert southwest of the US. The city of Los Angeles receives a meager 38 cm (15 in) of rain a year. Yet, the city has the highest water usage in California and some of the highest use rates in the country. You would never know by looking at the number of golf courses and car washes, and the abundance of lush, green lawns that the city is located in a desert. The same is true for Las Vegas, which receives significantly lower rainfall.

Los Angeles uses much more water than it receives from precipitation and thus it imports water from the northern part of California and from states to the east via the Colorado River. In fact, much of the development of Los Angeles was fueled by this supply of water from the Owens Valley in the Sierra Nevada and the Colorado River to the east. Water from the Colorado began to flow into Los Angeles in the 1920s and 1930s and included the construction of Parker Dam and the Colorado River Aqueduct.

Water Supply and Demand

LANDSAT image of Las Vegas showing the contrast between irrigated areas in the city and the surrounding desert The Los Angeles River, now a concrete channel fed by storm drains Parker dam on the border between California and Arizona Colorado River Aqueduct in the Mojave Desert

Click on the images above to see full size versions and complete source information.

Growth of other cities that lie in arid locations closer to the Colorado River, including Denver and Phoenix, will likely lead to bitter litigation over water rights in the southwest in coming decades. Overseas, countries in arid parts of the globe, for example Turkey, Iraq and Syria, have also had major disputes about water rights and management. Turkey, which lies at the source of the Tigris and Euphrates rivers, has constructed dams on both rivers for irrigation purposes as well as for hydroelectricity, and this has led to long conflicts with countries downriver including Syria and Iraq.

With projections for increasingly rapid growth of world population and coupled demand for water for drinking and agriculture, as well as for industry, maintaining a clean water supply looks to be one of the grand challenges of the 21st century. The goals of this module are to learn about how water is cycled on the Earth’s surface and how climate change coupled with growth of population will accentuate the global water crisis.