The Blue Planet: Water Resources

Water Coverage and Availability

• More than 70% of the Earth's surface is covered by water, earning it the nickname "Blue Planet".
• Only 3% of the Earth's water is freshwater, useful for human and animal consumption.
• Most of the freshwater is held in ice and groundwater, leaving only 10% in rivers, lakes, and wetlands, making it a finite resource.

Characteristics of Water

• Hydrology is the study of water.
• Limnology is the branch of science dealing with the characteristics of freshwater.
• Oceanography is the science that deals with about 97% of all Earth's water (ocean).

Distribution of Water on the Earth

• Water is the most abundant compound on Earth, covering nearly three-fourths of the planet's surface.
• More than 97% of the world's total supply of water is found in oceans and is too salty for drinking, irrigation, and most industrial and household needs.
• Approximately 2% of the Earth's water is in the form of glaciers and polar ice caps.
• Most of the rest is found underground (groundwater), and much of that is too difficult or too expensive to tap.
• Less than 0.01% of the Earth's total water is in lakes and rivers, which are the major sources of the world's drinking water.

Freshwater and Groundwater

• Freshwater is the term used to denote natural waters that have low concentrations (less than 500 ppm) of dissolved salts and solids.
• Freshwater includes the waters of lakes, rivers, ponds, and streams.
• Approximately 20% of the world's freshwater is under the soil, in the form of groundwater.
• Groundwater resides in aquifers, which are layers of porous rock that hold water.
• Seawater is often referred to as saline water, with a salinity of the mass in grams of dry salts present in 1 kg of seawater.