In this week’s edition of Nature is a paper which using recently gathered satellite data shows that groundwater in the Indian states of Rajasthan, Punjab and Haryana is being depleted at an alarming rate. The region concerned borders India’s long-time foe Pakistan.
Observations from NASA’s Gravity Recovery and Climate Experiment satellites, together with modelled soil-water variations, are reported by Matthew Rodell and others to show that the water table in the region which includes the capital Delhi is falling at an average rate of four centimetres per year, which equates to a volume of around 18 cubic kilometres per year. During the six year study period from 2002 to 2008, the net loss was some 109 cubic kilometres, which is double the capacity of India’s largest surface-water reservoir.
Rainfall throughout the period was normal, and the scientists show that soil moisture, surface water, snow, glaciers and biomass could not have contributed significantly to the observed decline. Rodell et al. conclude that unsustainable consumption of groundwater for irrigation and other industrial uses is the likely cause of the water loss. They also note that the consequences for the 114 million residents of the affected region may include a reduction in agricultural output and shortages of potable water, leading to extensive socio-economic stresses.
Extensive socio-economic stresses is something of an understatement when one considers the sensitive political geography of the region, and the fact that India and Pakistan are nuclear powers which have long been in armed conflict. The 20th century will be remembered for its ideology-driven wars, but the 21st century will likely see increasingly bloody conflicts arising from natural resource scarcity. Wars over water and other life essentials are inevitable, unless states develop ways of sharing resources across borders for the mutual benefit of their populations.
Rodell et al., “Satellite-based estimates of groundwater depletion in India”, Nature (2009)