Why in News?
A study by University of Delhi (DU) and Indian Institute of Science Education and Research (IISER), Bhopal, published in the Journal of the Geological Society of India, found that the Yamuna’s floodplains in Delhi have shrunk by nearly one-third over the last century, increasing flood vulnerability.
Key Highlights
- Study Area: 50-km stretch of the Yamuna in Delhi.
- Methodology: Historical maps (1799 onwards) and satellite imagery (up to 2024).
- Major Findings:
- River channel narrowed by ~68%.
- Formative discharge declined by ~89%.
- Around 45 sq km (one-third) of floodplains disconnected by embankments.
- Sediment deposits reduced from 20 sq km (1985) to 4 sq km (2020).
- Major Causes:
- Barrages (Hathnikund, Wazirabad, Okhla).
- Embankments.
- Rapid urbanisation and floodplain encroachment.
Key Term: Formative Discharge
- Also called Channel-Maintaining Discharge.
- The long-term river flow that shapes the river channel, transports sediment, and maintains its flood-carrying capacity.
- Floodplains: Flat, low-lying areas adjacent to a river that are periodically inundated during floods. Act as natural buffers by storing excess floodwater, recharging groundwater, and supporting biodiversity.
- Encroachment and embankments reduce their flood-moderating capacity.
[2026] Consider the following assertion:
In the Pleistocene period either the Yamuna once flowed into the Indus, or the Sutlej flowed into the Yamuna and one major tributary of either had shifted from the Ganga to the Indus or vice versa.
Which of the following is/are the basis of the above assertion?
1. The Nadi-Sukta of the Rigveda
2. The explorations of the Sutlej and the Yamuna by Robert Bruce Foote
3. The presence of the same species of dolphins in both the Indus and the Ganga river systems
Select the answer using the code given below:
[A] 1 only
[B] 2 only
[C] 1 and 2
[D] 3