Read the following passage and answer the questions given after it.
A great water scarcity looms over India; by 2025 Indians will get just over half the water they get today. This grave problem has a simple solution. Catch the rain as it falls, and the water crisis will disappear. However, about 80 per cent of India’s rainfall buckets down during the three months of the monsoons. As yet, no government programmer has discovered how to store this water. ‘Dying Wisdom’, a seven-year countryside study by Delhi’s Centre for Science and Environment, reveals that ruins of amazing ancient technologies survive in every corner of India. Drip-irrigation systems of bamboo pipes in Meghalaya; ‘kunds’, underground tanks in Rajasthan; ‘pynes’, water channels built by tribals in Bihar; and thousands of open-water bodies down south are all superb examples of rain water harvesting systems. Even today, tanks called ‘eris’ in Tamil Nadu water one-third of the state’s irrigated area. Unfortunately, governmental planners mostly refuse to acknowledge the potential of these low-cost systems, concentrating on costly dams and canals. Few cities have lost touch with their ecological traditions as fast–and with as damaging results–as Bangalore. Only 17 of its water bodies struggle to survive in a city where once 200 lakes, ponds and wetlands cooled the city and recharged its ground water. The threats continue unabated as the relentless march of urbanization shows no sign of stopping.
What, according to the passage, is the primary reason for the water shortage?