’ s message : The sunk cost fallacy of deep drilling

At the beginning of 2008, I visited a watershed located in Karkinatam village in the state of Karnataka, South India. There, crops are intensively irrigated using groundwater. The water table has been depleted from 5 m-depth to 50 m-depth in a large part of the area. Now, 42 % of a total of 158 water wells in the watershed are dry. Speaking with the farmers, I have been amazed to learn that they were drilling down to 500 m to tap water. This case is, of course, not isolated. Large regions, for example in South America, Africa and South Asia, are constituted by crystalline rocks. The same regions face water scarcity under arid to semi-arid conditions. Therefore, fractured crystalline aquifers constitute groundwater reserves that are exploited in many parts of the world. In India, groundwater pumped from hard rocks represents the main resource for irrigation and has been sustaining the Green Revolution (Swaminathan 2007) for several decades. The mining of groundwater resources leads to lowering of the water table. As a reaction, the farmers are ready to pay more for deeper boreholes which, most of the times, are found to be dry. This trend is not restricted to rural areas, as private well development in the cities faces the same trend. A detailed study of groundwater extraction in the world shows that the examples of deepening of wells up to hundreds of meters for water exploration in hard rocks are not limited to India but are also found in large numbers in other regions of the world (USA, Africa, etc).