Water, Forests and Soil Resources | CUET PG Geography | Notes

Water Resources

Water resources form a critical theme in physical and economic geography, dealing with the distribution, availability, utilization, and management of the Earth’s water in relation to human needs. Water is a renewable but finite resource, and although nearly 71% of the Earth’s surface is covered by water, only about 2.7% is freshwater, and of this, roughly 68.7% is locked in glaciers and ice caps, about 30% exists as groundwater, and merely a fraction of a percent is available as easily accessible surface water in rivers, lakes, and wetlands. This extreme scarcity of usable freshwater relative to total water on Earth underlies the global significance of water resource studies.

The Hydrological Cycle

The hydrological (water) cycle is the fundamental natural process governing the circulation and renewal of water resources, involving evaporation (from oceans, lakes, and rivers), transpiration (from plants, together termed evapotranspiration), condensation (formation of clouds), precipitation (rain, snow, sleet, hail), infiltration (percolation of water into soil, replenishing groundwater), and runoff (surface flow of water into streams, rivers, and eventually oceans). This cycle is solar-powered and ensures the continuous renewal of freshwater, making it a renewable resource at the planetary scale, even though it can be locally over-exploited and depleted faster than it is replenished.

Sources and Types of Water Resources

Water resources are broadly classified into surface water and groundwater. Surface water includes rivers, lakes, ponds, reservoirs, and wetlands, and is directly influenced by precipitation patterns, making it highly seasonal and variable, particularly in monsoon-dominated regions like India. Groundwater is water stored in the pore spaces and fractures of rock and soil formations known as aquifers; it is recharged through infiltration and is generally more stable and reliable than surface water but is vulnerable to over-extraction, which can lead to falling water tables, land subsidence, and in coastal areas, saline water intrusion. A distinction is also made between unconfined aquifers (where the water table is exposed to atmospheric pressure through permeable overlying material) and confined aquifers (trapped between impermeable rock layers, under pressure, sometimes giving rise to artesian wells when tapped).

Global and Indian Distribution

At the global level, water resources are highly unevenly distributed. Regions such as the Amazon basin, Congo basin, and Southeast Asia are water-abundant due to heavy rainfall, while regions such as the Middle East, North Africa (the Sahara), and Central Asia face chronic water scarcity. Brazil, Russia, Canada, Indonesia, China, Colombia, the USA, India, Peru, and Myanmar are often cited among the countries with the largest renewable freshwater resources in absolute terms, though per capita availability presents a very different picture, since it also depends on population size.

In the Indian context, water resources are dominated by the monsoon system, which delivers about 75% of the country’s annual rainfall within roughly three to four months (June to September), creating a highly seasonal pattern of availability. India’s major river systems are typically classified into the Himalayan (perennial) rivers — the Indus, Ganga, and Brahmaputra systems, which are fed by both monsoon rainfall and melting snow/glaciers, making them perennial — and the Peninsular (non-perennial or seasonal) rivers — such as the Godavari, Krishna, Kaveri, Mahanadi, and Narmada, which are rain-fed and therefore experience much greater seasonal fluctuation in flow. India’s per capita water availability has been steadily declining due to population growth, having fallen from over 5,000 cubic metres per capita per year at independence to roughly 1,400–1,500 cubic metres today, a level close to the internationally recognized “water stress” threshold of 1,700 cubic metres, with the more severe “water scarcity” threshold set at 1,000 cubic metres per capita per year (Falkenmark Indicator).

Uses of Water Resources

Water resources serve multiple competing uses. Agricultural use (irrigation) is by far the dominant consumer globally and in India, accounting for roughly 70% of global freshwater withdrawal and an even higher share (nearly 80–90%) in India, given the country’s dependence on irrigated agriculture for food security. Domestic use covers drinking water, sanitation, and household needs. Industrial use includes water for cooling, processing, and manufacturing. Additional uses include hydroelectric power generation, navigation and inland waterways, fisheries, recreation and tourism, and the maintenance of ecological flows necessary to sustain riverine and wetland ecosystems.