Why in the News
A global study published in Nature on 14 January reports widespread land subsidence across India’s major river deltas, driven largely by human activities and observed using Sentinel 1 satellite data.
Study at a Glance
- Data source Interferometric Synthetic Aperture Radar from ESA Sentinel 1
- Period 2014 to 2023
- Coverage 40 major global deltas including 6 Indian deltas
- Spatial resolution 75 metres
- Population relevance Deltas support over 340 million people globally
Indian Deltas Confirmed to be Sinking
- Ganges Brahmaputra Delta, Brahmani Delta, Mahanadi Delta, Godavari Delta, Cauvery Delta and Kabani Delta.
- More than 90 percent area affected in Ganges Brahmaputra, Brahmani and Mahanadi deltas.
Key Quantitative Findings
- Brahmani delta: 77 percent area sinking at more than 5 mm per year
- Mahanadi delta: 69 percent area sinking at more than 5 mm per year
- In Ganges, Brahmani, Mahanadi, Godavari and Kabani,
Subsidence rate exceeds regional sea level rise - Godavari delta: Even 95th percentile subsidence exceeds projected global sea level rise under worst climate scenario
- Kolkata: Subsidence equals or exceeds delta average due to urban load and resource extraction
Major Human Drivers Identified
- Unsustainable groundwater extraction: Ganges Brahmaputra and Cauvery deltas
- Rapid urbanisation: Brahmani delta
- Reduced sediment flux: Mahanadi and Kabani deltas
- Population pressure: Intensifies compaction and land lowering
| [2018] Which of the following is/are the possible consequence/s of heavy sand mining in riverbeds?
1. Decreased salinity in the river 2. Pollution of groundwater 3. Lowering of the water-table Select the correct answer using the code given below: (a) 1 only (b) 2 and 3 only (c) 1 and 3 only (d) 1, 2 and 3 |
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