A Lesson
There was a thirsty crow. It peered into an earthen pitcher. There was water at the bottom. "Dregs," it cawed alarmed. But it was thirsty. It began to drop pebbles into the pitcher. Drop by drop, the water rose to the top. The crow drank and flew away sated. It could have used a pneumatic drill to smash through to the water. It didn't.

This water harvester of a crow could teach us a thing or two.

The water arithmetic.

We stare at the dregs of our ingenuity, at a resource scientifically misutilised. We are cawing alarmed. But we only keep cawing, raucously at that. Lets get on, like the crow. Fashion a pebble-by-pebble approach to meet our needs.

First recognise that the source of all water on earth is not the river, is not the underground aquifer, is not the lake, well or stream. Rain is the source of all water.

, recognise that in India the monsoon is a deluge. Rain spatters the earth. Fills ponds. Lakes brim. Rivers heave. But the monsoon is also brief. We receive most of its rainfall in just 100 hours out of 8,760 hours in a year. But this is enough to meet our water needs, provide food security and eradicate rural poverty.
Water Balance in India
According to a study, India receives 400 million hectare meters (mham) of rain and snowfall. Another 20 mham flow in as surface water from outside the country. This total 420 mham provide the country with river flows of 180 mham. Another 67 mham is available as groundwater. About 173 mham is lost as evaporation or becomes soil moisture - which can be captured directly as rainwater or as runoff from small catchments in and near villages or towns. If even 20 - 3- mham can be captured through rainwater harvesting, tremendous pressure can greatly extend the availability of clean water. Why is Cherrapunji today short of drinking water when it gets more than 11 meters of rainfall annually? Simply because it does not capture the rain that falls over it.

Third, recognise the rainwater needs to be harvested through capturing, storing and recharging it and later using it during prolonged parched periods. The key component of water management is 'storage' especially in India. Small means even more water. Michael Evenari, an Israeli scientist's study clearly demonstrates that ten dams with one hectare catchment will store more water than one dam of ten hectare. Several other studies conducted by the Central Soil and Water Conservation Research Institute in different parts of the country revealed similar results.

Any land can be used to harvest rainwater. (See potential) In tune with the terrain, with nothing imposed. It is just a matter of using material locally abundant - stones, mud, bamboo etc.

The hidden link: The most beautiful thing about water harvesting is that there is a human-rain-land synergy. What the table shows clearly is that rainwater harvesting is possible in all human-land-rain scenarios.

Synergies exist between rainfall, human population density and land availability

Annual level of rainfall
Rain yield potential from one hectare of land (*)
Human population density
Land availability for water harvesting
Surface quality for water collection efficiency
Number of people whose water needs can be met at 100 litres per person per day from one hectare of land

100 mm

1 million litres





2,000 mm
20 million litres
Very high
Very low
More rooftops and built-up surfaces available with high runoff
(*)Assuming rainwater collection efficiency of 100 per cent

Water is what we make of it. COLLECTIVELY, promoting environmental self-reliance.

Find more about water harvesting systems
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