The purpose of this module
Source: International Women’s Tribune Centre, New York
The earth is gasping as much for fresh air as it is for water, and as the most essential natural resource for life, it is likely to become a critical scarce resource in many regions of the world in the coming decades. The source of all water on earth is precipitation in one form or another be it solid, liquid or gaseous), and is constantly on the move along the paths of the hydrological cycle, but man has little control over these.
Assessment of the run off, along with precipitation, infiltration and evaporation, becomes a prerequisite for the use management of the water resource, which is fast becoming scarce. The growing global concern that very soon the demand for water will outpace its supply capability, largely because of the streamrolling universal impact of urbanisation and industrialization, necessitates an urgent need for a reliable assessment of this valuable resource - water, locationwise, regionwise, countrywise, and so on.
When viewed from space the world is really a globe of water. Oceans cover 71% of the earth's surface, and polar ice and mountain glaciers cover a further 3.18%. If we add the small proportion (0.4% or 2.058 million sq.km.) covered by continental lakes, this leaves only one quarter of the earth's surface as land, including rivers and marshes.
The volume of water in the world would be sufficient to enclose the entire globe in a layer of water 2,718m deep. In the course of the earth's history this was prevented only by the fact that high and low areas were irregularly arranged on the solid surface of our planet as a result of geophysical processes and tectonic movements of the earth's crust.
Growing a day's food for one adult takes about 1,700 gallons of water (National Geographic Society, 1993)