Unit 4 – Environmental Sustainability Part 3 – Water and Change

World Water Supply 70% of the earth is covered in water 97% of that water is salt water (oceans) Of the last 3% only 0.3% is found in rivers/lakes. The rest is frozen. FRESH WATER IS A SCARCE RESOURCE

World Water Supply

Access to Water Humans cannot survive for more than a few days without water Access to clean drinking water is a major problem (over 1 billion people don’t have it) One of the targets of the Millennium Development Goals

Access to Safe Drinking Water Means? Drinking Water = used for domestic purposes (drinking, cooking, personal hygiene) Access = source of water is less than 1 km away (0.6 miles), each person of the house can obtain at least 20 liters (5 gallons) per day Safe = characteristics meet WHO guidelines

Unclean Water Using unclean water = high risk of disease Diarrhea Cholera Hookworm Hepatitis 1.6 million people die each year from diarrhea and cholera caught from unclean water

Water Supply Water supply is unevenly distributed (within and between countries) UN estimates by 2025, 2/3 of world’s population will live in countries that experience moderate to high stress on water supply Additional demand will come from manufacturing Increase in demand comes from LEDCs

Water Scarcity Physical Water Scarcity = Demand for water exceeds supply. Common in arid, semi-arid places Economic Water Scarcity = Water is available but people can’t afford it. Common in LEDCs, especially urban poor in the shanty towns

Water Scarcity

Water Pollution Water often becomes polluted when used, which further limits the supply of fresh water Pollutants can seep into groundwater Diluting the pollutants is slow and purification is expensive This = big problem in countries (many Asian) that rely heavily on groundwater supplies

Water Management Solve problems between competing demands (rural vs. urban) Some charge higher prices for water Forces people to regard it as a valuable resource Not popular in LEDCs because water for farming is a basic need for survival

Water Management Many believe irrigation systems are out of date and inefficient Drip systems use much less water but only account for 1% of the world’s systems Low incomes and lack of education in LEDCs make it hard to fix the problems

Future Water Use Demand will continue to grow Increase expected to be greater in LEDCs Mostly for domestic, industrial and livestock uses Largest use today is for irrigating farmland Prices are likely to rise in the future