Water Source & Sustainability
Water Water Everywhere
There is more than 1.4 billion cubic kilometres of water on the earth. If divided evenly enough to give every man, woman & child 230 million cubic meters. However 98% of that is saltwater and nearly 1% of it is locked as polar icecaps. Less than 1 percent of the Earth's freshwater is accessible in lakes, rivers, and groundwater aquifers. This vital 1 percent of available freshwater is con- stantly in motion, either flowing in rivers, evaporating and moving around the globe as water vapour, falling from the sky as rain or snow, or filtering slowly through the earth to emerge somewhere else. It is a renewable resource on which we all completely depend upon. It is the genesis and continuing source of all life on earth.
The most accessible water is that which flows in river channels or is stored in freshwater lakes and reservoirs. The major portion of the water diverted for human needs is taken from this renewable, readily accessible part of the world's freshwater resources. Although the total volume of water conveyed annually by the world's rivers is about 43,000 km3, most of this occurs as floods. The low river flows (base flows) make up only about 19,000 km3. Of this, about 12,500 km3 can be accessed, and present levels of withdrawal accounts for 4000km3. This withdrawal is expected to reach 5000 Km3 per year by the 2025. The demand for freshwater increased six-fold between 1900 and 1995 nearly twice the rate of population growth. One third of the world's population today already live in countries experiencing medium to high water stress.
Water Stress
Water stress for a river basin is defined as the water resources available in that basin. The water stress for a country is the summation of water stress for all its river basins. Water stress begins when the withdrawals of water of freshwater rises above 10 percent of renewable resources. Medium to high stress translates as water use that exceeds 20 percent of available water
There is more than 1.4 billion cubic kilometres of water on the earth. If divided evenly enough to give every man, woman & child 230 million cubic meters. However 98% of that is saltwater and nearly 1% of it is locked as polar icecaps. Less than 1 percent of the Earth's freshwater is accessible in lakes, rivers, and groundwater aquifers. This vital 1 percent of available freshwater is con- stantly in motion, either flowing in rivers, evaporating and moving around the globe as water vapour, falling from the sky as rain or snow, or filtering slowly through the earth to emerge somewhere else. It is a renewable resource on which we all completely depend upon. It is the genesis and continuing source of all life on earth.
The most accessible water is that which flows in river channels or is stored in freshwater lakes and reservoirs. The major portion of the water diverted for human needs is taken from this renewable, readily accessible part of the world's freshwater resources. Although the total volume of water conveyed annually by the world's rivers is about 43,000 km3, most of this occurs as floods. The low river flows (base flows) make up only about 19,000 km3. Of this, about 12,500 km3 can be accessed, and present levels of withdrawal accounts for 4000km3. This withdrawal is expected to reach 5000 Km3 per year by the 2025. The demand for freshwater increased six-fold between 1900 and 1995 nearly twice the rate of population growth. One third of the world's population today already live in countries experiencing medium to high water stress.
Water Stress
Water stress for a river basin is defined as the water resources available in that basin. The water stress for a country is the summation of water stress for all its river basins. Water stress begins when the withdrawals of water of freshwater rises above 10 percent of renewable resources. Medium to high stress translates as water use that exceeds 20 percent of available water