Global Water Supplies: Are They Sustainable Part Five, Issue 11 Global Water Supplies: Are They Sustainable

Objectives After reading the assigned chapter and reviewing the materials presented the students will be able to understand: How much water do people need? How much water is used in agriculture? What effect will climate change have on water supplies?

Introduction In 1977, California was in the midst of a powerful drought. Residents were forbidden to water their lawns or wash their cars. Health officials have shown that cholera, an often deadly bacterial infection can be controlled by a simple and cheap cloth filtration system for drinking water. One in six of the planet’s 6.4 billion people presently lack access to safe water and at least 2.4 billion do not have access to adequate sanitation. Water demand is projected to grow by 40% over the next 20 years. If this issue is to be addressed, hundreds of billions of dollars must be invested globally in water infrastructure.

The Hydrologic Cycle The movement of water at the earth’s surface is called the water or hydrologic cycle. The components of the cycle are evaporation, precipitation, runoff, and infiltration (fig 11-2, page 117). Water that infiltrates into the soil is called groundwater. Glaciers and permanent snow have 68.70% of the earth’s freshwater and fresh groundwater has 30.10%. The earth’s oceans have 97.50% of all water.

How Available is Water Globally Eighty percent of all illness in developing countries are water related, according to the UN. By UN estimates two-thirds of humanity, or as many as 5 billion people will face shortages of clean freshwater by the year 2025. Some toxic organisms are already resistant to chlorination, the most widespread technique to purify drinking water.

Who collects and distributes the Planet’s Water? Sizeable investments are required to extract, purify, and distribute water. The UN estimates that at least US $180 billion will be required globally to expand supplies over the next two decades. There is a lot of waste due to leaking pipes. Lack of water will generate refugees, the cost will be borne by other segments of society or other nations. Governments typically build and operate water distribution systems.

Impacts of Contaminated Water According to the UN, as many as 3 million children die each year from polluted water or water scarcity. It is one of the major factors driving mass migration, creating increasing number of human refugees. Humans need 500,000 liters a year to meet minimum human hygiene demands.

Water Use in the United States The United States uses about 400 billion gallons each day. This figure includes both consumptive use (the water is not put back where it came from) and non consumptive use (the water is put back after use). About three-fourths of all water used in California, is by agriculture. Subsidized prices to agribusiness meant massive waste. Most irrigation ditches were made of unlined dirt. Up to a quarter of the water trickled into the soil before reaching its destination. Up to 25 % evaporated from the ditches in 100 degree heat.

Climate Changes and Water Demand in California Studies on ancient trees have yielded valuable insight into climatic variability in California. Such studies confirm that California’s climate over the past millennium have been extremely variable, with severe drought conditions persisting for decades to centuries. Incorporating this data into computer forecasts, shows that California’s climate is going to become more extreme than in the recent past. This will force agonizing choices for providing water consumed by industrial agriculture, commerce, and municipalities.

Water and Development: The People’s Republic of China Over half the population must use drinking water that fails to meet minimum drinking water quality standards in China. Three reasons account for China’s degraded water: 1. Rapid and unregulated expansion of industry. 2. Failure to invest in infrastructure to meet growing need. 3. Reliance on sewage effluent to irrigate crops.

Water and Geopolitics: Israeli/Palestinian Water Conflict Water is one of the major areas of disagreement between the Israelis and Palestinians. Future water needs cannot be met by increasing supply from existing sources. Thus conservation, new supplies, or a combination of both will be needed, along with measures to address population growth.

Summary One in six of the planet’s 6.4 billion people presently lack access to safe water and at least 2.4 billion do not have access to adequate sanitation. Water demand is projected to grow by 40% over the next 20 years. If this issue is to be addressed, hundreds of billions of dollars must be invested globally in water infrastructure. The movement of water at the earth’s surface is called the water or hydrologic cycle. The components of the cycle are evaporation, precipitation, runoff, and infiltration . Water that infiltrates into the soil is called groundwater. Eighty percent of all illness in developing countries are water related, according to the UN. By UN estimates two-thirds of humanity, or as many as 5 billion people will face shortages of clean freshwater by the year 2025. The UN estimates that at least US $180 billion will be required globally to expand supplies over the next two decades. Humans need 500,000 liters a year to meet minimum human hygiene demands. Studies on ancient trees have yielded valuable insight into climatic variability in California.

Home Work  1. What are the components of the water or hydrological cycle? 2. What percentage of all illness in developing countries are water related, according to the UN? 3. What is the minimum human hygiene demand for water?