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Zorluk: Çok zorEnvironmental Hazards and Degradation

In highland regions prone to severe environmental degradation, unsustainable land clearing on steep slopes can set off a cascading eco-geomorphic hazard sequence. Arrange the following stages of this slope failure and hydrological hazard chain in their correct chronological order, from initial human trigger to final downstream impact:

  1. 1Deforestation and clear-cutting of deep-rooted forest vegetation on steep hillside slopes
  2. 2Rapid infiltration of heavy seasonal rainfall, leading to elevated pore-water pressure and reduced shear strength
  3. 3Gravitational failure and downslope displacement of saturated regolith as a catastrophic landslide
  4. 4Deposition of mass movement debris into the narrow valley drainage line, impounding streamflow behind a natural dam
  5. 5Structural outburst of the unstable debris barrier, releasing a destructive downstream flash flood surge

Cevap

The correct chronological order of the environmental hazard progression is: Deforestation and clear-cutting of deep-rooted forest vegetation on steep hillside slopes → Rapid infiltration of heavy seasonal rainfall, leading to elevated pore-water pressure and reduced shear strength → Gravitational failure and downslope displacement of saturated regolith as a catastrophic landslide → Deposition of mass movement debris into the narrow valley drainage line, impounding streamflow behind a natural dam → Structural outburst of the unstable debris barrier, releasing a destructive downstream flash flood surge.
The hazard cascade follows a direct cause-and-effect physical sequence: initial vegetation removal destabilizes slope soils; subsequent heavy rainfall saturates the exposed regolith, causing high pore pressure; gravitational slope failure (landslide) displaces soil into the valley river bed; the resulting sediment dam obstructs water flow; and hydraulic pressure ultimately bursts the temporary dam, triggering a downstream flash flood wave.

Adım Adım Çözüm

1
Identify the primary human land-use modification that initiates slope instability.
Deforestation on steep slopes strips root cohesion and canopy protection.
Vegetation removal is the foundational trigger altering the physical equilibrium of the hillside.
2
Determine the hydrological mechanism following canopy removal.
Unsheltered soil absorbs intense rainfall, building up high pore-water pressure in the regolith.
Without tree interception and root absorption, rainwater rapidly saturates unanchored surface material.
3
Trace the primary geomorphic response to soil saturation.
The overburdened, saturated regolith slides downslope under gravitational force (landslide).
High pore-water pressure reduces internal shear strength below the threshold of gravitational stress.
4
Analyze the immediate channelized physical consequence in the valley bottom.
Landslide sediment accumulates in the riverbed, forming a temporary debris dam.
Displaced slope mass settles directly across narrow drainage channels, obstructing natural river flow.
5
Evaluate the ultimate secondary hydrological hazard produced downstream.
Hydraulic head pressure behind the debris dam breaches the barrier, sending a surge downstream.
Unconsolidated landslide dams are structurally unstable and collapse rapidly under water pressure.

Anahtar Kavram

Cascading geomorphic and hydrological environmental hazards (mass wasting to debris dam outburst floods)
Tahmini Süre:2m 30s
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Konular

Environmental Hazards and Degradation

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