Rajasthan is the most water-scarce state in India. Its main geographical features are the Thar desert and the Aravalli Range. The Aravalli Range, running through the state from southwest to northeast, lies parallel to the direction of the oncoming monsoon winds, leaving the north-western part of the state in a rain shadow.
Around three-quarters of Rajasthan’s population of almost 69 million (2011 census) live in rural villages, relying for their livelihoods on agriculture, livestock and forestry. These communities are at the mercy of the monsoon, which often fails or is scanty. In the areas where we work, large-scale schemes such as pipelines or water towers, far from meeting rural communities’ water supply needs, are at best delivering infrequent, unreliable supplies (e.g. once per month), and at worst carry the precious resource of water away from rural areas to serve growing urban populations.
The monsoon season
The monsoon season in India officially runs from 1st June to 30th September. The rains typically arrive in Kerala first and gradually work their way north, reaching the south-west parts of Rajasthan around 15-20th June and the westernmost parts of the state by mid July. In 2018, the monsoon reached east Rajasthan on June 27th. Over the last four years, the rains have arrived in the state between June 24th and June 30th. During the winter, there can be a small amount of rain, called the ‘Mahavat’ due to the shallow cyclonic depressions originating over the east Mediterranean Sea.
On average, in total Rajasthan gets around 60cm of rain a year. The easternmost parts receive the highest amount of rainfall (sometimes around 100cm) and the regions in the Aravali hills see around 50cm, but the western regions of Rajasthan such as the Thar desert and the Kutch region of Gujarat receive less than 20cm of rain annually. The south-west monsoon, arriving between June and September, accounts for 90% of rainfall in Rajasthan. This compares to the 88cm in the UK and 133 days of rain spread throughout the year. However, it goes without saying that averages can be misleading and, in 2018, our project in the Kutch region in Gujarat received virtually no rainfall. Our projects in Jaisalmer also saw a very limited amount of rain. Conversely, 2019 saw a very strong monsoon in most places.
Rural water availability
Traditionally, rural people survived with very little water. They knew a lot about capturing and storing rainwater. Nowadays, however, the traditional wisdom is dying out as large-scale government-led schemes such as pipelines or water towers promise modern methods of water delivery. Sadly, far from meeting rural communities’ water supply needs, these schemes tend to deliver infrequent, unreliable supplies (e.g. once per month). In the worst cases, they carry the precious resource of water away from rural areas to service growing urban centres.
Increasingly unpredictable weather patterns
Rajasthan, along with much of the world, is seeing increasingly unpredictable weather patterns. Eleven of India’s fifteen hottest years on record have been since 2004. The heatwave this year once again raises the question of the impact of climate change on the people of Rajasthan and how we can further adapt our water harvesting structures to capture as much rain as possible. Firstly, we design our project schedules so that as many tanks as possible are ready in time for the monsoon rains. Secondly, we design the tanks to catch as much of the rain as possible. We ensure that all the taanka have three inlet pipes in the catchment area into the main tank, to ensure that as much water runs in as possible and doesn’t soak away. Where possible, we also have concrete catchment areas, as the run-off from these is higher than from the more traditional sand and earth surfaces. We also ensure that the catchment area is large enough to fill the tank. In our Barmer project, where houses have pukka (not thatched) roofs, we have combined roof rainwater harvesting with the more traditional catchment area to increase the rain caught. Furthermore, the simple design of the tank means that if rains come unexpectedly they will catch that rain: nothing extra needs to be done.