Addressing Groundwater Scarcity and Arsenic Pollution with Potential Solutions in India

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Episode recorded on September 19, 2023
Episode released on December 14, 2023

Abhijit is a professor at the Indian Institute of Technology in Kharagpur, close to the city of Kolkata, formerly Calcutta, in eastern India.

Highlights  |  Transcript

1. India, one of the most intensive groundwater using countries globally, using ~ 240 km³ of groundwater each year (Ministry of Jal Shakti, 2022; link). 
2. India after independence in 1947 focused on food security, initially with canal irrigation, then shifting to groundwater fed irrigation using tubewellls (~25 million by 1990s).

3. Irrigation linked to Green Revolution in India (Mukherjee, 2018). 

4. GRACE satellite data reveals widespread groundwater depletion, especially in NW India (Rodell et al., 2019; Long et al., 2016; Bhanja et al., 2020). 
5. World Bank Report: 50% urban dwellers, 80% rural dwellers (domestic use) rely on groundwater, 65% of irrigation depends on groundwater (World Bank, Wijnen et al.,2012).
6. India: diverse geology and geomorphology: Himalayas in North, Northern Indian Plains to the south (~30% of landmass, 70% of groundwater stored), very thick sediments, kms thick from mega-rivers (Indus, Ganges, Brahmaputra) with basement rocks in Peninsular India (~70% of landmass, ~ 30% of groundwater storge) (Mukherjee et al., 2015).  .
7. Thick aquifers in the north with up to 500 m usable groundwater, thin aquifers to south (~ 10 m regolith) underlain by crystalline fractured aquifers (50 – 100 m deep) (Malakar et al., 2021).
8. Similar distribution of aquifers in Africa, thick sedimentary aquifers in north (e.g., Nubian Aquifer etc) with think regolith aquifers underlain by crystalline basement in south.
9. India achieving food security, ~ 400 million people moved out of extreme poverty 2005 – 2019 (The Times of India, Jul 12, 2023). 
10. Groundwater in India linked to many of 17 sustainable development goals, food production, poverty alleviation, gender gap, eduction etc. 
11. Population density in India among highest globally (~477 people/km2 in 2022) (population density 2022). 
12. What Africa can learn from India: as groundwater demand increases in Africa, manage groundwater and surface water conjunctively, “one water”. 
13. Unlike Africa, India is becoming an economic powerhouse. 
14. In India, within the past seven years all water resources were placed under single ministry (Ministry of Jal Shakti). 
15. Water access is linked to energy. India is leader in solar power, ranking 4^th globally. Solar energy may lead to overexploitation of groundwater. 
16. The concept behind the Ganges Water Machine and Bengal Water Machine is that use of groundwater for irrigation creates space for recharge of high rainfall during monsoon, but it depends on subsurface geology, may be complicated by heterogeneity (Mukherjee et al., 2023). 
17. Heliborne EM surveys used to map subsurface geology in six pilot areas, reveal details of subsurface geology (National Aquifer Mapping Mission, NAQUIM) 
18. GRACE satellite data showed overexploitation of groundwater in NW India in late 2000s. MacAllister et al. (2023) showed net increase in groundwater storage in NW India and Central Pakistan attributed to canal irrigation over much of last century (~ 350 km³). Need space in subsurface to accommodate increased recharge from canals, may work in arid areas with deep water tables. 
19. Water quality issues: arsenic, largest mass poisoning in human history in E India and W Bengal, 21^st century (Smith, 2000). An estimated total of 250 million people exposed to arsenic. 
20. Shallow aquifers polluted with arsenic but deeper aquifers considered safer. Restrict irrigation pumpage to shallow aquifer and limit municipal water use to deeper aquifers. This concept works in multi-layered aquifers. Overexploitation of deep aquifer could cause arsenic laden shallow groundwater to move into deeper zones (Mukherjee et al., 2011; Khan et al., 2019). 
21. World Bank programs: Atal Bhujal Yojana (World Bank, 2020) 450 M USD to thousands of communities to manage water. This program began in 2020 (Mukherjee et al., 2021). 
22. Jal Jeevan mission, basically Waterlife, provide functional household tap connections in every rural home by 2024. 
23. ~ 50% of people in most parts of India do not have access to clean water. 
24. Estimated ~ 260 million people could be exposed to fluoride in groundwater (Sarkar et al., 2022). 
25. GRACE satellite data, increasing water storage in peninsular India (Bhanja et al., 2017), attributed to rural people digging pits in rural work program (social employment scheme, 100 days minimum work).. 
26. Future moving toward more sustainable groundwater development: should reduce groundwater use and ration electricity to limited time periods.