River basins losing resilience India’s reservoir decline is being mirrored by the deteriorating condition of its major river basins. Water availability in the Ganga Basin has fallen from nearly 50 per cent to 43.34 per cent of normal storage conditions. The Godavari Basin has declined to 36.52 per cent, while the Narmada Basin stands at 34.96 per cent. Among the most vulnerable systems is the Krishna Basin, where only 19.31 per cent of water storage remains available.
Eastern India’s Barak Basin also continues to show significant stress, while the Brahmani-Baitarani, Cauvery and Mahanadi-Pennar basins are reporting below-normal conditions. The shrinking of river basin storage carries implications far beyond reservoir management. River basins function as complex hydrological systems that support agriculture, groundwater recharge, fisheries, biodiversity, industries and millions of livelihoods. Declining storage therefore reflects a weakening of the broader ecological resilience of India’s freshwater systems.
Environmental geographer Dr. Pravat Kumar Shit observed that the current crisis is the result of several interconnected climatic and anthropogenic pressures acting simultaneously. “Below-normal rainfall during recent months prevented adequate replenishment of reservoirs and river systems,” he explained. “At the same time, heatwaves and rising temperatures associated with climate change are increasing evaporation losses from reservoirs and surface water bodies. Excessive water extraction for irrigation, drinking water and power generation is further intensifying the decline.” According to him, the present trend reveals how climate variability is interacting with unsustainable water use patterns to create cumulative hydrological stress across India. Heatwaves and evaporation losses One of the least visible but most critical dimensions of the crisis is the role of extreme heat in accelerating water loss.
Large reservoirs lose substantial quantities of water through evaporation, particularly during prolonged heatwave conditions. Over the last decade, India has witnessed increasing frequency and intensity of extreme heat events. Surface temperatures exceeding 45 degrees Celsius are now common across several regions during pre -monsoon months. Such high temperatures significantly increase evaporation rates from reservoirs, rivers and open water bodies. Scientists note that reservoirs located in dry and semi-arid zones are especially vulnerable. As water surfaces expand across large shallow reservoirs, evaporation losses rise dramatically during summer.
In some areas, the amount of water lost through evaporation rivals agricultural consumption. This process creates a dangerous feedback loop. Lower reservoir levels expose more shallow margins, increasing surface heating and further accelerating evaporation. Simultaneously, shrinking water storage reduces the ability of reservoirs to buffer drought conditions later in the season. Climate researchers warn that rising global temperatures are likely to intensify this pattern in coming decades. Even where annual rainfall remains stable, increasing heat may substantially reduce effective water availability. Groundwater: IndiaÊs invisible crisis The reservoir emergency is unfolding alongside a far deeper groundwater crisis that many experts believe represents the greatest long-term threat to India’s water security.
Groundwater has become India’s primary freshwater reserve, supporting irrigation, drinking water supply and industrial activities across both rural and urban regions. Yet decades of excessive extraction have severely depleted aquifers in many parts of the country. Studies conducted by the Central Ground Water Board between 2003 and 2014 analysed groundwater conditions from more than 19,000 observation wells across India. The findings revealed widespread decline in groundwater levels, particularly in shallow unconfined aquifers that are highly dependent on rainfall recharge. Satellite-based observations over the last 25 years further demonstrate severe groundwater depletion trends.
Northern India has experienced depletion rates ranging between zero and minus five centimetres annually. Western and southern India are recording groundwater decline between zero and minus two centimetres per year. West Bengal itself is witnessing an average groundwater decline of nearly minus four centimetres annually, raising concern over long-term water sustainability in the state. The Ganga-Brahmaputra Basin remains among the most vulnerable regions. Studies indicate groundwater depletion exceeding 0.4 cubic kilometres per year in parts of the basin.
Given that this region supports one of the highest population concentrations in the world, continued groundwater decline poses a direct threat to food production and rural livelihoods. Experts warn that India’s groundwater crisis has remained largely invisible because depletion occurs beneath the surface and often escapes public attention until wells begin to fail. However, the falling reservoir levels now reveal how both surface and subsurface water systems are simultaneously under pressure. Deficient rainfall deepens uncertainty Recent rainfall trends have further intensified concern. According to data from the India Meteorological Department, nearly 27 per cent of India’s districts experienced deficient rainfall during the pre-monsoon period between March and May 2026.
Earlier, between January and February, nearly 70 per cent of the country recorded deficient or negligible rainfall. These prolonged dry conditions significantly reduced river discharge and reservoir inflow. In many agricultural regions, farmers became increasingly dependent on groundwater extraction to sustain pre-kharif cultivation. Hydrologists note that rainfall deficiency affects water systems in multiple ways. Reduced precipitation lowers direct reservoir inflow, decreases soil moisture, weakens groundwater recharge and diminishes river discharge. The cumulative impact gradually weakens the hydrological stability of entire river basins.
In recent years, rainfall variability has also become increasingly erratic. Instead of evenly distributed seasonal precipitation, many regions now experience concentrated extreme rainfall events separated by long dry spells. Such rainfall patterns generate rapid runoff but contribute relatively little to groundwater recharge or long-term reservoir storage. Climate scientists believe this emerging rainfall behaviour represents one of the clearest hydrological signatures of climate change across South Asia. Water becoming a political question As water scarcity intensifies, the issue is increasingly moving beyond environmental discourse into the centre of India’s political and economic landscape. Interstate river disputes, groundwater conflicts, irrigation allocation and dam management are now shaping regional politics across multiple states.
Questions surrounding river interlinking, hydropower expansion and transboundary water sharing are also becoming more contentious under conditions of increasing scarcity. Experts warn that future water conflicts may emerge not merely from absolute shortage but from unequal access, ecological degradation and competing developmental priorities. The growing pressure on India’s reservoirs therefore reflects a much larger transformation underway within the country’s environmental systems. Reservoirs, once viewed primarily as engineering structures for irrigation and flood control, are now becoming indicators of climate vulnerability, ecological stress and resource insecurity. As India waits anxiously for the monsoon, the rapidly declining reservoir levels across the country are serving as a stark warning that the nation’s water future may become increasingly unstable unless long-term ecological and hydrological reforms are urgently undertaken.
(The writer is a senior staff reporter with The Statesman)