Drainage of Waterlogged Soils - 1 | Agriculture Optional Notes for UPSC PDF Download

What is Water Logging?

Waterlogging is the condition where the soil in a specific area becomes completely saturated with water, leading to a rise in the water table.

• Effects of Waterlogging:
  • Waterlogging can result in soil displacement, impeding the normal flow of air through soil pores and hindering plant growth.
  • Reduced airflow in the soil leads to decreased oxygen levels and increased levels of carbon dioxide and ethylene.
• Causes of Waterlogging:
  • Waterlogging can be triggered by various factors, including: a. Excessive irrigation b. Abundant rainfall c. Flooding d. Poor drainage systems
• Consequences of Waterlogging:
  • Waterlogging severely restricts plant growth and productivity, particularly in anaerobic conditions, often leading to the death of certain crops and plants.
  • The excess water in the soil profile weakens plant roots, causing them to wither or rot.
• Ongoing Issue:
  • Waterlogging can persist as an ongoing problem even when there is no visible excess water on the soil surface, making it a hidden but detrimental issue.

Causes of Water Logging

Physiography

• Waterlogging can be influenced by the topography, slope, shape, and drainage patterns of a location.
• The physiography of an area determines the speed of surface runoff and the time it takes for soil to drain surface water.
• Low-lying areas like valleys, depressions, and flat lowlands are more prone to waterlogging as surface water tends to accumulate in these areas, forming natural swamps and waterlogged lands.
• Water cannot easily flow downhill due to gravity in such regions, leading to water buildup over time.

Weather Conditions

• Weather is a natural factor contributing to waterlogging, with regions experiencing continuous or heavy rainfall being more susceptible to temporary or permanent waterlogging.
• Intense and prolonged rainfall can elevate the water table, causing waterlogging.

Soil Type

• Waterlogging is more likely in heavy clay soils, such as black cotton soils, and soils that are prone to surface sealing as they can retain rainwater for extended periods, leading to rapid waterlogging.

Geology

• Presence of an impermeable layer beneath the topsoil hinders rainwater infiltration, resulting in a false water table or perched water table.
• Areas with shallow soils, surface hardpans, and high water tables are more prone to waterlogging, particularly during heavy rainfall.

Seepage Inflows

• Waterlogging can result from seepage and inflow from neighboring water sources like lakes, shallow aquifers, canals, and rivers.
• Subsurface flows from higher to lower areas can also contribute to waterlogging.

Excessive Irrigation and Poor Drainage System

• This is a human-induced cause of waterlogging, and it can be exacerbated by ineffective irrigation and drainage practices.
• Irrigation, in addition to natural rainfall, can introduce water to the soil profile.
• Waterlogging may occur due to excessive irrigation, inadequate drainage, poor irrigation management, obstruction of natural drainage, and seepage from canals.

Types of Water Logging

Waterlogging can be categorized into the following types:

Riverine Flood Waterlogging

• This type of waterlogging occurs during the rainy season when excess water from rivers floods the surrounding areas, resulting in waterlogging.
• The water accumulates on the land, causing damage to various plants and crops.

Oceanic Flood Waterlogging

• Oceanic flood waterlogging, as the name suggests, is characterized by ocean waters overflowing onto nearby lands and causing waterlogging.
• This often happens during significant weather events like hurricanes and tsunamis.

Seasonal Waterlogging

• Seasonal waterlogging occurs during the rainy season when runoff water accumulates in low-lying areas and depressions, leading to waterlogging.

Perennial Waterlogging

• Perennial waterlogging occurs when rainwater collects in deep water bodies or swamps and then flows into adjacent fields, resulting in persistent waterlogging.

Sub-soil Waterlogging

• This type of waterlogging occurs when water tables rise significantly, especially during the rainy season, causing waterlogging in the soil.