Rainwater Harvesting Around The World - India

About Rajasthan:

Rajasthan is the largest Indian state by area and the seventh largest by population, compromising mostly of the harsh and inhospitable Thar Desert (also known as the Great Indian Desert). Even though Rajasthan is the largest state, it possesses just 1.2% of the total surface water and only 1.7% of the groundwater available in India. Known as one of the most challenging and arid habitats in Asia, there are no main rivers running through Rajasthan and it has a turbulent climate, with erratic rainfall and long periods of drought. This means civilians have always had to be super smart and strategic about harvesting rainwater!

Modern interventions and water systems implemented by the state’s government in recent decades, like massive dams and piped systems, have largely underperformed or even failed. It’s the tried and trusted rainwater harvesting techniques listed below, that have been around for centuries, that have kept Rajasthan families and farms hydrated, and have proven themselves to be more cost-effective, easy, and beneficial than more modern systems.

2. Taanka

This rainwater harvesting system dates back to at least 1607 AD and is traditionally found in most houses and temples in the city of Bikaner in Northern Rajasthan (see map above). A ‘taanka’ is a small underground tank, built right next to the main house or in the courtyard where rainwater from the roof and surface run-off is caught. They are built by digging circular holes in the ground of 3-4 metres in diameter, before lining it in cement plaster and polished lime tiles, which helps keep the water cool and the lime acts as a disinfectant. The water stored in tankaas is used for drinking and domestic purposes, and more modern-day ones have a capacity of around 21,000 litres.

4. Johad

Johad’s are small earthen check dams that capture and conserve rainwater runoff. These catchment dams are still widely used throughout Rajasthan today, especially in the city of Alwar (see map above), and offer many benefits to the local people and environment. First and foremost, Johad’s provide locals with access to reliable, clean water for drinking, washing and irrigation. They also greatly improve and promote downward percolation through the soil (making the land more fertile), and recharge ground water in this extremely dry region. Johad’s are very simple and low-cost structures that require no large equipment or expensive materials to build, just local tradesmen and basic materials found in the surrounding environment. Workers simply dig a pit, building a semicircular mud barrier with the excavated soil, and add a stone drain to allow the excess water to seep into the ground (or to connect with other johads nearby).

Between 1984-2000 over 3,000 johads were revived in 650 villages in Rajasthan, and the impact on the local environment was astounding. Locals have measured a 6m rise in the groundwater level since, and the area saw a 33% increase in forest cover. Five local rivers that used to dry up and disappear straight after monsoon season are also now flowing strong all year round!