Chapter 3 Solutions — Water Resources

Freshwater is mainly obtained from surface run off and ground water that is continually being renewed and recharged through the hydrological cycle.

Because all water moves within the hydrological cycle, it is constantly recharged, ensuring that water is a renewable resource.

In the semi-arid and arid regions of Rajasthan, particularly in Bikaner, Phalodi and Barmer, almost all houses traditionally had underground tanks or 'tankas' for storing drinking water. A tanka could be as large as a big room; one household in Phalodi had a tank 6.1 metres deep, 4.27 metres long and 2.44 metres wide.

The tankas were part of a well-developed rooftop rainwater harvesting system and were built inside the main house or the courtyard, connected to the sloping roofs of the houses through a pipe. Rain falling on the rooftops would travel down the pipe and be stored in these underground tankas.

The first spell of rain was usually not collected, as it would clean the roofs and the pipes; the rainwater from the subsequent showers was then collected. This water could be stored till the next rainfall, making it an extremely reliable source of drinking water, especially in the summers. This rainwater, called 'palar pani', is considered the purest form of natural water. Some houses even built underground rooms adjoining the tanka to beat the summer heat.

Water scarcity is the shortage of water. Even areas with ample water resources can face it — for example many of our cities.

Its main causes are over-exploitation, excessive use and unequal access to water among different social groups. It also results from a large and growing population and consequent greater demand (for domestic use and food production), over-exploitation to expand irrigated agriculture, industrialisation and urbanisation, and bad (polluted) quality of water.