Water overuse is damaging the environment in many major basins. High overuse tends to occur in regions heavily dependent on irrigated agriculture, such as the Indo-Gangetic Plain in south Asia, the North China Plain and the High Plains of North America, and in areas undergoing rapid urbanization and industrial development. An estimated 1.4 billion people now live in river basin areas that are ‘closed’ (in that water use exceeds minimum recharge levels) or near closure. As millions of people in water-stressed areas are discovering, the environment is foreclosing on unsustainable water debts on an extensive scale. For example, farmers near Sana’a in Yemen have deepened their wells by 50 meters over the past 12 years, while the amount of water they can extract has dropped by two-thirds. Some people in water-stressed areas have the economic resources, skills and opportunities to leave their water problem behind. Many millions, such as small farmers, agricultural laborers and pastoralists in poor countries, do not (Human Development Report 2006).