A team of scientists has unearthed one of the most detailed climate records from peninsular India through sediment analysis of the Kondagai inland lake in Tamil Nadu’s Sivaganga district, offering new insights into monsoon patterns, ancient ecosystems and human settlement over nearly 4,500 years.
The study, conducted by researchers from the Birbal Sahni Institute of Palaeosciences (BSIP), an autonomous institute under the Department of Science and Technology, reconstructed past rainfall, vegetation shifts, lake levels and flood events using a combination of stable isotope analysis, pollen studies, grain-size measurement and radiocarbon dating.
Researchers collected 32 closely spaced sediment samples from just over a one-metre core beneath the lakebed, allowing unusually high-resolution climate reconstruction for inland Tamil Nadu — a region with limited well-dated lake records despite its sensitivity to the Northeast Monsoon.
The findings, published in the journal Holocene, identified three major climatic phases over the Late Holocene period: the 4.2 ka arid event, the 3.2 ka dry phase and the Roman Warm Period. According to the study, these phases had direct links to monsoon variability, lake hydrology and human activity in the region.
The lake lies close to Keeladi, an important archaeological site where evidence of an urban settlement linked to the Sangam era has been uncovered. Scientists said the environmental history of Kondagai provides valuable context for understanding how ancient communities responded to climatic stress, water scarcity and ecological change.
The study’s long-term monsoon baseline is seen as crucial for improving climate forecasting in Tamil Nadu, where droughts, extreme rainfall and floods pose recurring challenges. Officials noted that the findings could support water management strategies in districts such as Sivaganga and Madurai by guiding reservoir restoration, groundwater recharge, tank rehabilitation and climate-smart agricultural planning.
Researchers said the identification of ancient flood deposits, land destabilisation phases and sediment inflow patterns could also help in disaster risk mapping for the Vaigai basin, supporting predictions of flood vulnerability and land degradation.
From an ecological standpoint, the study provides data for wetland and lake restoration by tracking changes in aquatic productivity and oxygen conditions over millennia, aiding evidence-based biodiversity and conservation strategies.
Ministry of Science & Technology said the research strengthens archaeological interpretation, heritage planning and environmental policy by linking climate behaviour with cultural and ecological transformations in southern India.
