DEMISE OF DHOLAVIRA (INDUS VALLEY SITE): CONNECTIONS TO CLIMATE CHANGE

The Dholavira site is located in the low lying Rann of Kutch. Latest accelerator based radiocarbon dating suggests the beginning of occupation at least from 3,500 years BCE (pre Harappan), and continuation until 1,800 years BCE (early part of the Late Harappan period). However, the settlement possibly started earlier since the oldest settlement level could not be dated due to lack of datable material.

The city expanded very rapidly from 2,900 BCE to 2,400 BCE when the inhabitants of Dholavira switched over from use of mud bricks to stone bricks for making houses and fortification walls. They built citadel, bailey, lower and middle town much like what are found in most other contemporary cities like Harappa and MohenjoDaro. These were probably due to social hierarchy where people from different segments of the society engaged in different activities used to live. During this peak period, their craftsmanship – making of potteries, ornaments – rapidly improved. Probably they started long distance trade with other IVC sites, even to Mesopotamia. This is known as urban Harappan period when it reached its acme.

Dholavira is the most spectacular IVC site in India and the fifth largest in the sub-continent in terms of area. It is the largest excavated Harappan site in India which can be seen by tourists. All other sites were buried and covered up after the excavation was over. But Dholavira is unique because it records continuous settlement at one given place for over 1,700 years. It shows excellent city planning, wide roads, architecture with geometric precision. More importantly they adopted a very advanced water conservation and harvesting system from building series of connected reservoirs, stone and terracotta drainage pipes to wells. They also built dams on the two rivers Mansar and Manhar which flowed around this city during this time. The dry river beds of these rivers can be seen even today. During this long period, the climate changed severely from a good monsoon to weak monsoon. But they sustained themselves by adopting water conservation techniques, suggesting their resilience and participatory nature of the society. The only thing that is yet to be studied is their burial history.

The demise of this site was connected to climate change. It was analysed high resolution oxygen isotopes in mollusc shells. These are found aplenty in Dholavira, many of them were finely cut by humans and being consumed for food. These molluscs typically grow in mangrove suggesting that the people were harvesting them from nearby mangroves. The isotopes tell about the sources and the seasonality of water in which these animals grew. Surprisingly, after analysis of the Early to Mature Harappan molluscs (2,700 year BCE old), it looked that they grew in a water that is only possible if glacial meltwater mixes in the mangrove. The seasonality was high. This clearly suggested that a glacier fed river was debouching in the Rann of Kutch. But then isotopes in the molluscs from terminal part of Mature to late Harappan from 2,300 to 2,100 years BCE indicated that the glacial contribution disappeared and seasonality reduced. This is the time that exactly coincides with the decadence and fall of the city of Dholavira, as indicated by the archaeological evidence and the onset of the newly-proposed Meghalayan stage (a division of geological time) by an international body of geologists and stratigraphers. The monsoon was anyway declining. When the Meghalayan drought came lasting a few centuries, the whole city collapsed. The collapse of Harappan Dholavira was near-synchronous to the decline at all the Harappan sites in India like Kalibangan, Lothal, Rakhigarhi as well as Mesopotamia, and the Old Kingdom of Egypt and China.

Harappans emerged at a time when monsoon was good and they sustained their cities by agriculture in fertile river banks. When monsoon started decreasing, the Harappans displayed genius to adopt water conservation. Not only this, they changed their crop pattern from water intensive crops like rice to millets. Just think about their modern outlook. Even today we cannot change the crop pattern in drought prone areas with all our mighty technology, satellite surveys and communications. The final blow to the Harappans, however, was the Meghalayan stage of global drought. It caused the collapse of all major ancient cityscapes across the globe. This seems like fiction but it teaches us two important lessons. One, we must learn quickly how to cope up with the reduced monsoon and water deficit due to climate change, specially our agriculture. Second, if we do not learn then a catastrophe is waiting for us.

Matter referenced:

Anindya Sarkar , Professor of Geology and Isotope Geochemistry at IIT, Kharagpur, Times of India, Ahmedabad, Wednesday, 26th February, 2020.

By: Dr. Bhawana Asnani.

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