Srinagar, Oct 15: Lake Ahansar in Kashmir’s Ganderbal district has preserved a record of nearly 750 years of environmental change, offering fresh insights into how human activity may have altered the Valley’s rivers, wetlands and agricultural landscape.

A study published in the journal Catena in 2026 identifies a major shift around 1600 CE, when lake sediments changed from being dominated by mineral material carried from the surrounding landscape to deposits richer in organic matter produced within the lake.
Researchers attribute the transition partly to a weakening hydrological connection between the lake and the Jhelum River, alongside changes in land use and floodplain management. However, they caution that the available evidence does not establish any single intervention as the direct cause.
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.
The team reconstructed the lake’s environmental history by analysing a 268-centimetre sediment core collected in September 2023. The investigation combined geochemical measurements, carbon and nitrogen isotopes, radiocarbon dating and historical records.
The findings identify two distinct phases. Between 1285 and 1600 CE, sediments were largely composed of mineral material transported from the surrounding watershed, suggesting stronger river influence and greater sediment inflow.
After around 1600 CE, organic matter became more prominent, indicating increased biological productivity within the lake and reduced delivery of mineral sediments from the surrounding landscape. The estimated timing of the transition carries a calibrated uncertainty range of 1510 to 1635 CE.
The shift coincided with extensive landscape changes during the Mughal period. Researchers suggest 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 from 1859 and 1945 further indicate a gradual decline in the lake’s hydrological connection with the river.
Covering approximately 0.17 square kilometres at an elevation of around 1,583 metres, Lake Ahansar is a remnant of an older river-lake system shaped by the Jhelum’s changing course. It now has an artificial outlet on its western side to regulate excess water discharge into the river.
The researchers also examined climate variability, particularly the Little Ice Age, as a possible explanation. However, the sediment record did not support climate as the sole driver, suggesting that changes in land use and river connectivity also played a significant role.
Changes in lead enrichment were detected after around 1600 CE, potentially reflecting growing human and economic activity. The study, however, could not establish the specific source.
The authors acknowledge that limited archaeological evidence and the absence of high-resolution palaeoecological indicators prevent them from determining precisely how human interventions transformed the lake.
The findings underline how alterations to river channels, wetlands, drainage systems and surrounding land can produce lasting ecological changes. They also highlight the importance of understanding historical environmental shifts while developing conservation strategies for Kashmir’s lakes.
The researchers caution that the findings cannot automatically be generalised to every lake in the Valley. Nevertheless, the study demonstrates how lake sediments can provide valuable evidence of long-term environmental change and help guide future wetland conservation.