Experts say it may point to alarming changes in groundwater dynamics, health of ecosystem
SHILLONG, April 22: A new analysis of satellite data by the Centre of Excellence for Natural Resource Management and Sustainable Livelihoods (CoE-NRM&SL) under the Meghalaya Basin Development Authority (MBDA) has revealed a striking 27% rise in the state’s water bodies over the past eight years.
Two independent studies, one from 2006 to 2017 and another from 2014 to 2022, confirmed a steady increase in surface water coverage across the state. Though this could be interpreted as a positive development in a water-stressed region, experts warn that it may point to alarming changes in groundwater dynamics and health of ecosystem.
Dr Subhash Ashutosh, IFS (Retd), Co-Chairman and Director of CoE-NRM&SL, told The Shillong Times that the increase in water bodies cannot simply be attributed to better rainfall or short-term fluctuations.
“This may actually point to impaired water percolation in hilly terrain, leading to waterlogging in low-lying areas. If that’s the case, it’s a red flag for the health of our ecosystems,” he said.
Another study, conducted in mid-2022, focused on areca nut plantations across seven 100 sq km grids but yielded an unexpected finding — a notable surge in water body areas across all grids. RiBhoi district, in particular, recorded an astonishing 631% increase.
To validate these findings, a comprehensive “wall-to-wall” study was conducted from October 2023 to March 2024 using LANDSAT imagery and the Normalised Difference Water Index. Researchers mapped water bodies larger than 0.36 hectares across the state during non-rainy months in 2014 and 2022, carefully eliminating cloud-related distortions. The study used over 60 satellite scenes.
The results showed a significant jump — from 11,350 hectares in 2014 to 14,432 hectares in 2022. While districts like South West Khasi Hills, West Khasi Hills, and East Garo Hills saw a steep rise, others such as Ri-Bhoi, East Khasi Hills, and East Jaintia Hills recorded a decline.
Ashutosh said, “At first glance, the increase in surface water might seem positive, but it could actually be a symptom of ecosystem degradation. It correlates with declining spring flows and dwindling groundwater levels — even in areas with high rainfall.”
Explaining the methodology and findings further, he said, “We mapped surface water for the entire state over an eight-year period during drier months — from October to March — to avoid seasonal bias. The findings were startling. They validated earlier indications from a smaller study and showed a significant spread of water in plain areas. This, we believe, is linked to degraded forest cover and diminished soil absorption capacity.”
Forest quality, rainfall patterns, and slope runoff are central to this trend.
“Rainfall intensity has increased, but it’s occurring over fewer days,” Ashutosh said, adding, “This leads to higher surface runoff, soil erosion, and less water percolation. Our forests are no longer absorbing water the way they used to.”
He also said that forest degradation, both in coverage and quality, has accelerated the shift. “In places like Garo Hills, for instance, you’ll see entire landscapes now dominated by areca nut plantations. These monocultures don’t support the same level of water absorption as natural forests.”
The implications extend beyond ecology. According to Ashutosh, this phenomenon affects everything including spring water availability and urban water supply schemes to flood patterns and agriculture. Even Mawphlang and Sohra, known for their rainfall, are now seeing water stress, he said.
The CoE-NRM&SL has urged the government to commission a third-party study through a premier institution like NESAC or IIT Guwahati to verify these findings.
“Such data has long-term policy implications. We need deep-dive studies because water is interconnected — with soil, forest, land use, and agricultural practices,” he said. While MBDA is actively working on watershed conservation, source sustainability, and drone-based micro-level planning, Ashutosh said macro diagnostics like this surface water study are crucial.
“You can think of this as a state-level X-ray. It gives you the big picture. Now, when we plan water supply schemes, we must also focus on preventing runoff, harvesting catchment water, and creating check dams wherever needed.”
He added that the state is now using GIS and drone technologies for identifying micro-catchments and planning infrastructure accordingly.
MBDA has also undertaken other landmark studies, including Meghalaya’s first bamboo resource assessment, covering over 7,000 sample plots. This has already spurred the establishment of what could be the country’s largest bamboo-based industry in Garo Hills.
The study was undertaken by Samuel Cooper Sungoh, Fettleman Dohling, and Norita Nongbet Sohlang under the direction and supervision of Subhash Ashutosh.