Water Availability and Potential in India

Water Availability and Potential

Water exists on Earth in two primary forms: surface water and groundwater.

Surface Water:

Surface water is found in various forms such as rivers, lakes, ponds, and canals. Among these, rivers are the most significant source of surface water. India is fortunate to have a multitude of major, medium, and small rivers. The collective annual flow in all Indian river basins is approximately 1,869 cubic km. However, due to geographical, hydrological, and other limitations, only around 690 cubic km (32 percent) of available surface water can be effectively used. Among these rivers, 13 are categorized as major rivers, covering a total catchment area of 252.8 million hectares. The largest river system is the Ganga-Brahmaputra-Meghna, spanning about 110 million hectares. Other major rivers with catchment areas exceeding 10 million hectares include the Indus, Godavari, Krishna, and Mahanadi. Medium-sized rivers have a combined catchment area of approximately 25 million hectares, with around 40% of utilizable surface water resources found in the Ganga-Brahmaputra-Meghna System.

Groundwater:

Part of the rainwater seeps into rocks and soil, forming groundwater. The latest assessment indicates that India's annual replenishable groundwater resource is estimated at 433 billion cubic meters (bcm), with 399 bcm deemed available for development across various applications. The Ganga and Brahmaputra basins account for about 46% of the total replenishable groundwater resources. Groundwater recharge mainly occurs through precipitation infiltration to the water table, natural recharge from streams, lakes, and ponds, as well as recharge from irrigation, reservoirs, and other systems. Groundwater discharge encompasses evaporation from the capillary fringe in areas with shallow water tables, transpiration by vegetation, natural discharge via seepage and spring flow to water bodies, groundwater outflow, and artificial discharge through pumping or drainage.

Groundwater utilization is notably high in northwestern river basins and parts of southern India. States such as Punjab, Haryana, Rajasthan, and Tamil Nadu have substantial groundwater utilization, while others like Chhattisgarh, Odisha, and Kerala utilize a smaller portion of their groundwater potential. States like Gujarat, Uttar Pradesh, Bihar, Tripura, and Maharashtra are moderately utilizing their groundwater resources. The exploitation of groundwater resources is limited in areas dominated by hard rocks in the peninsular plateau region.

Water Demand and Usage:

India's historical economy has been agrarian, with around two-thirds of its population relying on agriculture. At present, the primary driver of water demand in India is irrigation for agricultural purposes. Agriculture accounts for the majority of both surface water (89%) and groundwater (92%) utilization. While the industrial sector's water usage is limited to 2% of surface water and 5% of groundwater, the domestic sector's contribution is higher (9%) in surface water utilization compared to groundwater.

The world's water resources are predominantly composed of oceans, accounting for 96.5% of the total volume, while only 2.5% exists as freshwater. Most of this freshwater, around 70%, is found in ice sheets, glaciers, and mountainous regions, with almost 30% stored as groundwater in aquifers. India receives roughly 4% of global precipitation and ranks 133rd worldwide in terms of water availability per person annually. Its renewable water resources are estimated at 1,897 square kilometers per year. However, it's projected that significant parts of India will experience absolute water scarcity by 2025.

India faces significant challenges in its water sector due to rapid industrialization and urbanization. Supply augmentation potential is limited, groundwater levels are dropping, and water quality problems are becoming more prominent. Deeper drilling for water leads to contamination from fluoride and arsenic, while rivers and groundwater are polluted by untreated waste. Climate change adds complexity with increased rates of precipitation and evapotranspiration intensifying flood and drought impacts. Conflicts over water use are growing, and agricultural water use efficiency stands at just 38%, far lower than other countries. Demand for water in India is rising due to population growth and economic expansion.

Estimates of available water for human use vary, with Ministry of Water Resources figures suggesting adequate availability. However, more realistic calculations considering evapotranspiration predict a strained demand-supply balance due to population and economic growth. The 2030 Water Resources Group predicts that, if current demand patterns persist, about half of the water demand will go unmet by 2030.

A paradigm shift is needed in water resource management in India. This shift involves transitioning from an engineering-focused approach to a multidisciplinary, participatory one for irrigation projects. There's an emphasis on improving water use efficiency, sustainable groundwater management through aquifer mapping, watershed restoration, and groundwater recharge. Rural drinking water, sanitation, and urban water supply projects need innovative approaches, while recycling and reuse of water by industries should adhere to international standards. Flood management should emphasize non-structural methods, and water-related data collection and transparency should improve. Adaptation strategies for climate change impacts and a new legal-institutional framework for water are essential. Rivers suitable for inland waterways could be utilized for environment-friendly transportation.

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