Current Affair 1:

Why in the news?

Geological events have been on the rise since 2017 in the Sedongpu Gully watershed drained by the Yarlung Tsangpo River on the Brahmaputra in Assam.

A recent study has highlighted the high frequency of pollution, especially since 2017, in Sedongpu Bay in the Tibetan Plateau.

More about the news

1. These events are associated with extreme heat waves in the region, where temperatures rarely exceeded 0º C prior to 2012.
2. Mass dissipation is the movement of rocks and soil down a slope by gravity. Flow caused by splashes, crowd movement, or both.
3. Studies suggest that this change could have a negative impact on India, especially on the Northeast region.

Sedongpu Gully:

It is located in the Sedongpu Glacier and its valley. The valley is 11 kilometers long and covers an area of ​​66.8 square kilometres. Near Great Bend, it flows into the Yarlung Zangbo (Tsangpo) River.

What is Mass Wasting?

Mass wasting is the downslope movement of rock, soil, and debris under the influence of gravity. It includes various types of slope movements such as rock falls, slumps, and debris flows.

Key Triggers for Mass Wasting:

Heavy rainfall can saturate soil, increasing its weight and making it more prone to movement.

1. Quick melting of snow can add significant amounts of water to the soil, leading to instability.
2. Earthquakes (Seismic activity) can shake the ground and initiate landslides.
3. Volcanic Eruption can destabilise slopes through eruptions and associated seismic events.
4. Erosion by water bodies can undercut slopes and lead to mass wasting.

Types of Mass Wasting Events:

1. Rock Fall or Topple: This involves the falling, bouncing, and rolling of rock debris down a slope. It can occur suddenly and with significant impact.
2. Landslides and Rock Slides: These events involve large masses of soil and rock sliding down a slope.
3. Debris Flows: A debris flow is a rapid downslope movement of water-saturated rock debris and soil, resembling wet cement. It moves quickly and can be very destructive.
4. Avalanche: An avalanche is a sudden mass movement of rock or ice under gravity. It can occur in both mountainous and glacial regions.
5. Slope Creep: This is a gradual, slow movement of soil and rock down a slope, often imperceptible over short periods but significant over longer timescales.

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