India, April 19 -- T ehran is currently in the midst of its sixth consecutive year of extreme drought (a combination of critically low rainfall, empty reservoirs and high temperatures). Satellite images show vast water bodies across the country shrinking into thin trickles. About 750 km from the capital, Urmia, once the Middle East's largest lake, has dwindled to less than 10% its former size. From about 6,000 sq km, it now covers just 581 sq km. Beneath the ground, the crisis runs deeper. As Iran, like so many countries, overuses groundwater, falling levels, combined with changing rainfall patterns and extensive dam construction, have led to the shrinking of wetlands and lakes. Adding to the problem is the prevalence of water-intensive crops such as rice and watermelon. Things could have been different. Over the past 70 years, Iran - again, like so many others, including India - neglected and abandoned ancient water management systems. In Iran's case, the qanat or water-tunnel system had helped support the arid country for thousands of years. These sloping, covered tunnels were dug into hillsides and built along plains to channel rainwater and springwater, protecting it from the region's harsh heat. Dams did the opposite, exposing reservoirs to temperatures that routinely cross 50 degrees Celsius. With the qanats quietly crumbling, when scarcities hit, people dug wells and tapped into groundwater instead. The vicious cycle had begun as far back as the 1950s. Water management and agricultural reform will be the keys to the path forward, says Kaveh Madani, the Iranian director of the United Nations thinktank on water, who also worked within the environment ministry in Iran until his views caused him to be alienated. "Modern management can learn from the Persians, whose qanats helped societies thrive in some of the driest places in the world, for thousands of years." The very definition, he adds, of sustainable....