Properties of Water and

its Global DistributionPresented by-

Md. Inzamul Haque SazalChanchal Biswas

Department of Geography and EnvironmentShahjalal University of Science & Technology, Sylhet-3114,

Bangladesh

Basic properties of Water

• Polar molecule• Cohesion and Adhesion• High Specific Heat• Density-Greatest at 4 degree• Universal Solvent of Life

Polarity of WaterA water molecule is a polar molecule with opposite ends of the molecule with opposite charges.• Oxygen is more electronegative, the region around oxygen has a partial negative charge.• The region near the two hydrogen atoms has a partial positive charge.

Cohesion and AdhesionEssentially, cohesion and adhesion are the "stickiness" that water molecules have for each other and for other substances.

• Cohesion refers to the sticking together of alike molecules, such as water molecule being attracted to another water molecule.

• Cohesion also causes water molecules to form drops.

• Adhesion may refer to the joining of two different substances due to attractive forces that hold them.

High Specific HeatSpecific Heat is the amount of heat that must be absorbed or lost for one

gram of a substance to change its temperature by 1oC.

• Because water has a high specific heat, it can absorb large amounts of heat energy before it begins to get hot.

• It also means that water releases heat energy slowly when situations cause it to cool.

• The specific heat of water is 1 cal/g/ºCSanta Barbara 73°

Los Angeles(Airport) 75°

Pacific Ocean 68°

Santa Ana 84°

Burbank90°

San Bernardino100°

Palm Springs106°

Riverside 96°

San Diego 72°40 miles

70s (°F)80s90s100s

Density of Water• Most dense at 4oC• Contracts until 4oC• Expands from 4oC to 0oC•Ice is about 10% less dense than water at 4oC.•Density of water prevents water from freezing from the bottom up.•Ice forms on the surface first—the freezing of the water releases heat to the water below creating insulation.

Water- The Universal Solvent of Life

• Water is a versatile solvent due to its polarity, which allows it to form hydrogen bonds easily

• Most biochemical reactions occur in water– When an ionic compound is dissolved

in water, each ion is surrounded by a sphere of water molecules called a hydration shell

– This feature also enables water to carry solvent nutrients in runoff, infiltration, groundwater flow, and living organisms

Three States of Water• Water molecules are the

only substance on Earth that exist in all three physical states of matter: solid, liquid, and gas.

• In terms of heat being transferred into the atmosphere, approximately 3/4's of this process is accomplished by the evaporation and condensation of water.

Distribution according to volume

The total volume of water on Earth is estimated at 1.386 billion km³ (333 million cubic miles), with 97.5% being salt water and 2.5% being fresh water. Of the fresh water, only 0.3% is in liquid form on the surface. In addition, the lower mantle of inner earth may hold as much as 5 times more water than all surface water combined (all oceans, all lakes, all rivers).

So We Can Study the Earth’s Water Into Two Distinct Categories

• Salt Water Resource- oceans, salt water lakes etc.

• Fresh water Resource- ground water, river etc.

Distribution of Salt water Resources•Continental crust contain large quantities of easily eroded salts of the alkali and alkaline earth metals. •Salt has, over billions of years, accumulated in the oceans as a result of evaporation returning the fresh water to land as rain and snow.•As a result, the vast bulk of the water on Earth is regarded as saline or salt water, with an average salinity of 35% (or 3.5%, roughly equivalent to 34 grams of salts in 1 kg of seawater).

Distribution of Fresh Water ResourcesSurface water:Surface water is water in a river, lake or fresh water wetland. Surface

water is naturally replenished by precipitation and naturally lost through discharge to the oceans, evaporation, and sub-surface seepage.

Ground Water:Sub-surface water, or groundwater, is fresh water located in the pore

space of soil and rocks. It is also water that is flowing within aquifers below the water table.

Frozen Water:Several schemes have been proposed to make use of icebergs as a

water source, however to date this has only been done for novelty purposes. Glacier runoff is considered to be surface water.

• Desalination:Desalination is an artificial process by which saline water (generally

sea water) is converted to fresh water.

Distribution of River Water The total volume of water in rivers is estimated at 2,120 km³ (510 cubic miles), or 2% of the surface fresh water on Earth. Rivers and

basins are often compared not according to their static volume, but to their flow of water, or surface runoff.

Interesting Facts•Rain is the main source of all fresh water in the earth.•Fresh water journey starts from the high of the mountains; biggest source: Tepius of Venezuella•Worldwide lakes held 20 times more freshwater than all rivers.•Only East Africas Rift Vally holds three of the worlds largest lake: Malawi, Tangniyika and Victoria.•Bikal lake in eastern Siberia-the oldest lake of the world, carry 1/5 of all fresh water.•Amazon-the biggest river in the world can carry as much as water of next top ten biggest river combined.•Pantanal is the world largest wetland.•2 thousand million tones of sediments eroded to the Himalayas delivered to the Bay of Bangal via Bangladesh in every year.