The groundwater storage levels of the Ganga Basin, home to one of the world’s largest groundwater reservoirs, have been on a steady decline, depreciating by 2.6 centimeters per annum. This alarming revelation comes from a recent report titled “Estimation of Groundwater Storage Loss for the Indian Ganga Basin Using Multiple Lines of Evidence.”
Findings from the Report
The study detailed that between 1996-2017, groundwater levels decreased at an average rate of 2.6 cm per year. A notable tool used to gather this data was the Gravity Recovery and Climate Experiment (GRACE) satellites. Launched in 2002, these satellites evaluate Earth’s water bodies over land, ice, and ocean. Their findings showed that there had been an average annual loss of about 1.7 cm.
The average storage decline for the states of Uttar Pradesh, Bihar, and West Bengal was calculated to be about 2 cm per year, 1 cm per year, and 0.6 cm per year respectively. However, the impacts were drastically more severe in areas like Rajasthan, Haryana, and Delhi. Here, the average storage declines were estimated to be roughly 14 cm per year, 7.5 cm per year, and 7.2 cm per year, respectively.
These significant declines are due in large part to high groundwater abstraction rates particularly seen in places like Delhi and Haryana. The worst hits were felt in areas such as the West and southwest regions, agriculturally intensive regions, and urban locations like Delhi and Agra. The Brahmaputra basin is also noted as having a greater groundwater level reduction than both the Ganga and Indus basins.
Ganga River System Overview
The Ganga River, extending over 2,510 km of mountains, valleys, and plains, is known for its status as India’s longest river and most sacred river in the eyes of Hindus. The Ganga basin sprawls across India, Tibet (China), Nepal, and Bangladesh, spanning an area of 10,86,000 Sq. Km.
In India, the Ganga basin’s reach extends to encompass areas in Uttar Pradesh, Madhya Pradesh, Rajasthan, Bihar, West Bengal, Uttarakhand, Jharkhand, Haryana, Chhattisgarh, Himachal Pradesh, and Union Territory of Delhi, draining nearly 26% of the country’s total geographical area.
The river originates from the snowfields of the Gangotri Glacier in the Himalayas and descends the valley to Devprayag where it joins with the Alaknanda and is then known as Ganga. This river is joined by multiple other rivers such as Yamuna, Son, Ramganga, Ghaghra, Gandak, Kosi, Mahananda, Chambal, and Betwa.
One notable inhabitant of this river is the endangered Ganges River Dolphin. After flowing into Bangladesh and joining the Brahmaputra (Jamuna), the river continues as Padma, widening into the Ganges Delta in the Sundarbans swamp of Bangladesh before flowing out into the Bay of Bengal.
Groundwater Levels and their Categories
The groundwater levels across the country can be categorized under three segments: Over-exploited, Critical, and Semi-critical. Over-exploited refers to scenarios where groundwater extraction exceeds recharge, i.e., it is more than 100%. Subsequently, the critical category denotes areas where extraction ranges between 90-100% of recharge, while semi-critical represents extraction rates between 70%-90%.
As per the National Compilation on Dynamic Groundwater Resources of India, 2017 report, just over a third of assessment units are classified as Over-exploited (17%), Critical (5%), or Semi-Critical (14%). However, these statistics have shifted slightly with the 2020 report listing 16% of units as Over-exploited, 4% as Critical, 15% as Semi-critical and 1% as Saline, with the remaining considered safe.
The Central Groundwater Authority (CGWA) was established under Section 3(3) of the Environment (Protection) Act, 1986 to control and regulate the development and management of groundwater resources. As per the Food and Agriculture Organization (FAO) of the UN, India has the greatest extent of areas equipped for irrigation using groundwater (39 million ha).
Namami Gange and National Mission for Clean Ganga (NMCG)
The Namami Gange and National Mission for Clean Ganga (NMCG) are programmes designed to address issues around water scarcity and river preservation, but they have had mixed results. To better preserve the river Ganga, there is need for quantum leaps beyond incremental inputs.