Water Resources and the Changing Needs

Abstract

Only 3% of the total water on Earth is fresh water, out of which underground water constitute 29% and less than 1% is in the form of lakes and rivers on the Earth’s surface. The total freshwater resources in the world are estimated to be in the order of 43,750 km3 year−1, distributed throughout the world. In the coastal areas, fresh groundwater is present as a lens over the sea water. Due to increasing human population, urbanization and intensification of agriculture freshwater demand have been increasing. At the same time industrial and domestic use is growing relative to that for agriculture. Global assessment points to the fact that the demand for water is influenced by population growth, industrial development, and food production besides climate change. Total global freshwater withdrawal is estimated at 3800 km3 in which 70% for irrigation, with huge variations across and within countries. Since the balance between water demand and water availability has reached critical level in many regions of the world and increased demand for water and food production is likely in the future, a sustainable approach to water resource management has become imperative. This chapter highlights various sources, demand, and supply and management of fresh water with special reference to coastal freshwater resources.