 is likely to be severely underestimated for many countries like India. Over-abstraction, where withdrawal exceeds recharge, is occurring in a number of Middle Eastern countries and also in Turkey and Mauritania. By 2000 some 25% of Mexico's aquifers were known to be overexploited in arid parts of the country. A similar picture is also expected to be true of India and China in certain regions. In India, Pakistan, China and Iran a significant proportion of the population depends on groundwater abstractions, through a high number of very small structures. In Asia this was part of the "green revolution" of the 1960/70s. In contrast, in Mexico and the United States there are fewer but larger structures controlled by a smaller number of people. Evidence shows that crop yields in areas using groundwater are invariably greater as these water sources tend to be more stable than surface sources. A recent EU study has highlighted the economic benefits of irrigation and the INFRASTRUCTURE TO 2030: TELECOM, LAND TRANSPORT, WATER AND ELECTRICITY - ISBN 92-64-02398-4 © OECD 2006 5. THE IMPACTS OF CHANGE ON THE LONG-TERM FUTURE DEMAND FOR WATER SECTOR INFRASTRUCTURE future challenges from the WFD and CAP (Vecino and Martin, 2004). In areas of Spain for example - where irrigation uses 80% of all water supplied, and for which 20% comes from groundwater - irrigation with the latter leads to crop production five times as economically productive, and provides three times the employment, compared with other areas where there is surface irrigation. The reliability of supplies is estimated to result in twice the economic value of simply increasing the volume; hence opening up groundwater access in India in the 1960/80s has led directly to a stabilisation of agricultural production and been a major part of India's economic development and decline in poverty of rural communities. In view of the lack of, or poor quality of, groundwater data in these "boom" areas, it is impossible to gauge the possible future macro-level implications of de