Question

Difficulty: EasyEnvironmental Hazards and Degradation

In dry agricultural zones, poor irrigation management can lead to land degradation through soil salinization. Arrange the following stages of soil salinization in the correct sequential order from initial human cause to final environmental consequence.

  1. 1Application of excessive irrigation water to agricultural fields with inadequate drainage.
  2. 2Elevation of the underground water table and accumulation of stagnant water near root zones.
  3. 3Upward movement of salt-laden water toward the surface through capillary action due to high surface evaporation.
  4. 4Formation of a dense saline crust on topsoil, rendering the land toxic for crop cultivation.

Answer

The correct sequence begins with the application of excessive irrigation water, followed by the elevation of the water table, then the upward capillary movement of salt-laden water during evaporation, and concludes with the formation of a toxic saline crust on the topsoil.
The sequence correctly reflects the physical stage progression of salinization: over-irrigation adds excess water, causing the water table to rise; high evaporation then draws salt-laden water upward via capillary action; finally, water evaporates leaving a toxic crust of salt on topsoil.

Step-by-Step Solution

1
Identify the initial anthropogenic cause.
Excessive irrigation water is applied to farmlands without effective drainage.
Human water management practices initiate the degradation cycle.
2
Determine the immediate subsurface hydro-geological change.
The local water table rises, saturating the topsoil root zone.
Undrained excess water collects underground near the surface.
3
Trace the physical transport mechanism of minerals.
Capillary action draws dissolved subterranean salts upward as surface moisture evaporates under hot weather.
High evapotranspiration creates a vertical suction force carrying dissolved salts.
4
Identify the ultimate land degradation outcome.
A white saline crust accumulates on topsoil, inhibiting plant growth.
Water evaporates completely into the atmosphere, leaving solid mineral salts deposited on top of the soil.

Key Concept

Process of Soil Salinization
Rate this question