Ganderbal, Nov 10: Lake Ahansar in central Kashmir’s Ganderbal district has preserved a record of nearly 750 years of environmental change, offering important insights into how human activities and changes in river connectivity may have transformed the Valley’s wetlands, rivers and agricultural landscape.
A study published in the international scientific journal Catena in 2026 has identified a significant environmental shift around 1600 CE, when the lake’s sediment composition changed from being predominantly mineral-based to deposits containing a greater proportion of organic matter.
Titled “Historical Floodplain Transformation of the Kashmir Valley Recorded by Sedimentological and Geochemical Analyses of Lake Ahansar Sediments,” the study was conducted by Aasif Mohmad Lone, Debajyoti Paul, Elodie Brisset, Anchana Pulikkal, Hema Achyuthan and Vincent Rinterknecht.
According to the researchers, the transition indicates a weakening hydrological connection between Lake Ahansar and the Jhelum River, alongside changes in land use and floodplain management. However, the study cautions that the available evidence does not establish any single human intervention as the direct cause.
The research team reconstructed the lake’s environmental history by analysing a 268-centimetre-long sediment core collected in September 2023. The investigation involved geochemical measurements, carbon and nitrogen isotope analyses, radiocarbon dating and historical records.
The findings identify two distinct environmental phases. Between 1285 and 1600 CE, the lake sediments were largely dominated by mineral material transported from the surrounding watershed, indicating stronger river influence and greater sediment inflow.
However, after around 1600 CE, organic matter became increasingly prominent, suggesting higher biological productivity within the lake and a reduced delivery of mineral sediments from the surrounding landscape. The estimated timing of this transition carries a calibrated uncertainty range of 1510 to 1635 CE.
Researchers have linked this transformation partly to extensive landscape changes during the Mughal period, suggesting that agricultural expansion, land reclamation and water-management activities may have altered drainage patterns, reduced floodwater inflow and weakened the lake’s connection with the Jhelum.
Historical maps dating back to 1859 and 1945 also indicate a gradual decline in the lake’s hydrological connectivity with the river.
Spread over approximately 0.17 square kilometres at an elevation of around 1,583 metres, Lake Ahansar is considered a remnant of an older river-lake system shaped by changes in the course of the Jhelum. The lake currently has an artificial outlet on its western side to regulate the discharge of excess water into the river.
The researchers also examined climate variability, particularly the Little Ice Age, as a possible factor behind the environmental transition. However, the sediment record did not support climate change as the sole explanation, pointing instead to the combined influence of land-use changes and declining river connectivity.
An increase in lead enrichment was also detected in the sediments after around 1600 CE, potentially reflecting growing human and economic activity, although the study could not establish its specific source.
The authors acknowledged that limited archaeological evidence and the absence of high-resolution palaeoecological indicators restrict their ability to determine precisely how historical human interventions transformed the lake.
The study highlights how changes in river channels, wetlands, drainage systems and surrounding land use can produce long-lasting ecological consequences. It also underlines the importance of understanding historical environmental transformations when developing conservation and restoration strategies for Kashmir’s vulnerable water bodies.
The researchers, however, cautioned against automatically generalising the findings to every lake in the Valley, while emphasising that sediment records provide valuable scientific evidence for understanding long-term environmental changes and guiding future wetland conservation efforts. (CNS)
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