Water Inventory.docx

WORLD’S WATER The world's total water supply of about 332.5 million mi3 of water, over 96 percent is saline. Of total freshwater, over 68 percent is locked up in ice and glaciers. Another 30 percent of freshwater is in the ground. Rivers are the source of most of the fresh surface water people use, but they only constitute about 300 mi3 (1,250 km3), about 1/10,000th of one percent of total water.

DISTRIBUTION OF EARTH’S WATER Source of water

Volume of water in km³ (cu mi)

% total water

1,338,000,000 (321,000,000)

96.5

Ice and snow

24,364,000 (5,845,000)

1.76

Glaciers

24,064,000 (5,773,000)

1.74

Groundwater

23,400,000 (5,600,000)

1.69

Saline groundwater

12,870,000 (3,090,000)

0.93

Fresh groundwater

10,530,000 (2,530,000)

0.76

Lakes

176,400 (42,300)

0.013

Saline lakes

85,400 (20,500)

0.0062

Fresh water lakes

91,000 (22,000)

0.0066

Soil moisture

16,500 (4,000)

0.0012

Oceans

Atmosphere

12,900 (3,100)

0.00093

Swamps

11,470 (2,750)

0.00083

Rivers

2,120 (510)

0.00015

Biological water

1,120 (270)

0.000081

OCEANS

Volume of water in km³ (cu mi)

% total water

Pacific Ocean

669,880,000 (160,710,000)

48.3

Atlantic Ocean

310,410,900 (74,471,500)

22.4

Indian Ocean

264,000,000 (63,000,000)

19.0

Southern Ocean

71,800,000 (17,200,000)

5.18

Arctic Ocean

18,750,000 (4,500,000)

1.35

Continent or region

River runoff (km³/year)

% of total world

North America

7,800

17.9

South America

12,000

27.6

Europe

2,900

6.7

Middle East and North Africa

140

0.3

Sub-Saharan Africa

4,000

9.2

Asia (excluding Middle East)

13,300

30.6

Australia

440

1.0

Oceania

6,500

14.9

Hydrological CycleProcess of hydrological cycle starts with oceans. Water in oceans, gets evaporated due to heat energy provided by solar radiation and forms water vapor. This water vapor moves upwards to higher altitudes forming clouds. Most of the clouds condense and precipitate in any form like rain, hail, snow, sleet. And a part of clouds is driven to land by winds. Precipitation, while falling to the ground, some part of it evaporates back to atmosphere. Portion of water that reaches the ground, enters the earth’s surface infiltrating various strata of soil and enhancing the moisture content as well as water table. Vegetation sends a portion of water from earth’s surface back to atmosphere through the process of transpiration. Once water percolates and infiltrates the earth’s surface, runoff is formed over the land, flowing through the contours of land heading towards river and lakes and finally joins into oceans after many years. Some amount of water is retained as depression storage.

DITRIBUTION OF WATER IN INDIA

India has 2.45 per cent of the world’s landmass supporting 16 per cent of the world’s population whereas the freshwater resources are only 4 per cent of that of the world. Total Precipitation- 4000bcm Total water availability- 1869 bcm Total utilizable water- 1123 bcm Total surface water- 690bcm Total ground water- 433bcm

The rivers of IndiaThe average annual water availability in the river-systems of the country is assessed at 1,869 bcm.

Rainfall in IndiaAverage Annual Rainfall

- 1170 mm

Maximum Average Annual Rainfall - 11000 mm (Cherrapunji) Minimum Average Annual Rainfall - 100 mm (Western Rajasthan)