Groundwater Depletion and Associated CO₂ Emissions in India

Abstract

India, the world's largest groundwater user, withdraws about 230‐billion‐m3 groundwater annually for irrigation. Excessive groundwater pumping in India leads to rapid groundwater depletion and CO2 emissions. Here using multiple data sources (observation wells and Gravity Recovery Climate Experiment) to estimate groundwater depletion in India, as well as the associated chemistry and the pumping energy requirements, we provide the first estimate of the potential CO2 emissions due to bicarbonate extraction (CO2 release due to lowering of groundwater table) and groundwater pumping. We show that combined annual CO2 release due to bicarbonate extraction and pumping in India is approximately 32.01–131.74 million tons (31.29–131.02 million tons for pumping and 0.72 million tons for bicarbonate). The total estimated groundwater depletion in India is in the range of 122 to 199 billion m3 from the observation wells (1996–2016) and Gravity Recovery Climate Experiment (2002–2016). The CO2 emissions due to bicarbonate (~0.72 million tons/year) are dominated by those due to groundwater pumping (31.29–131.02 million tons/year) in India. However, the total (pumping and bicarbonate) estimated annual CO2 emission from groundwater is less than 2–7% of the total (annual) CO2 emission from India. Based on our unique data set collected from more than 500 farmers in Punjab, we show that a low‐cost intervention for irrigation scheduling based on soil moisture information can provide a sustainable solution by reducing groundwater pumping and CO2 emissions. The environmental problem of groundwater depletion in India is much more serious than the associated CO2 emissions, and hence, there is an urgent need for a regulation of groundwater use.

Flow velocity and nutrients affect CO2 emissions from agricultural drainage channels in the North China Plain

“…CO 2 emissions Description References 9.7 -13.5 Mt CO 2 y −1 Groundwater irrigation global estimate (Wood and Hyndman 2017) ∼ 10 Mt C y -1 Global groundwater extraction (Macpherson 2009) ~0.72 Mt CO 2 y -1 Groundwater irrigation in India (Mishra et al 2018) 1.7 Mt CO 2 y −1 Groundwater irrigation in the U.S. (Wood and Hyndman 2017) 0.52 ± 0.07 Mt CO 2 y −1 Groundwater depletion in the NCP this study 8.72 Mt CO 2 e y −1 GHG emissions of energy use for irrigation water pumping in the NCP (Qiu et al 2018) 120.87 Mt CO 2 e y −1 GHG emissions from agricultural production process in the NCP by life cycle assessment (Zhang 2019) 121 Mt CO 2 y −1 CO 2 emissions from central heating supply due to natural gas usage in the NCP (Cui et al 2019) 15…”

“…Thus, CO2 emissions from groundwater pumping should be considered in global carbon budgets (Currell et al 2010;Mishra et al 2018). This is especially relevant because groundwater depletion is expected to acceleration in the future (Zhao et al 2019).…”

Flow velocity and nutrients affect CO2 emissions from agricultural drainage channels in the North China Plain

“…A previous study indicates that groundwater loss in the NCP was approximately 50 km 3 within 8 years, which is greater than the capacity of China's Three Gorges Dam (39.3 km 3 ), the world's largest power station [7]. Thus, CO 2 emissions from groundwater pumping should be considered in global carbon budgets [72,73]. This is especially relevant, because groundwater depletion is expected to acceleration in the future [74].…”

“…This is especially relevant, because groundwater depletion is expected to acceleration in the future [74]. Groundwater irrigation global estimate [11] 10 Mt C year −1 Global groundwater extraction [9] 0.72 Mt CO 2 year −1 Groundwater irrigation in India [73] 1.7 Mt CO 2 year −1 Groundwater irrigation in the US [11] 0.52 ± 0.07 Mt CO 2 year −1 Groundwater depletion in the NCP This study 8.72 Mt CO 2 e year −1 GHG emissions of energy use for irrigation water pumping in the NCP [75] 120.87 Mt CO 2 e year −1 GHG emissions from agricultural production process in the NCP by life cycle assessment [76] 121 Mt CO 2 year −1 CO 2 emissions from central heating supply due to natural gas usage in the NCP [77] 15.99 Mt CO 2 year −1 Crop burning emissions during harvest seasons in the NCP [78]…”

Strong Influence of Changes in Terrestrial Water Storage on Flood Potential in India

“…Rapid groundwater depletion is one of the most critical sustainability‐related challenges in India (Asoka et al., 2017; Rodell et al., 2009; Tiwari et al., 2009). Assessments based on in situ and GRACE observations showed a considerable decline in groundwater storage in north India (Rodell et al., 2009; Tiwari et al., 2009), which is linked with groundwater pumping for irrigation and the changing characteristics of the summer monsoon (Asoka et al., 2017, 2018; Mishra et al., 2018). About 70% of food grain production comes from irrigated agriculture, which primarily depends on groundwater (Gandhi et al., 2009).…”