49.1. Causes of Water Logging

• Excessive application of water to agricultural fields beyond crop requirements causes percolation beyond the root zone. • This increases the groundwater table, leading to saturation of the root zone. • Common in regions with assured irrigation like canal command areas.

Over-irrigation occurs when farmers apply more water to their fields than the crops actually need. When too much water is added, it seeps down past the roots into the layer below, known as the root zone. This excess water raises the groundwater level, making the soil overly wet. This situation is often found in areas where irrigation practices are heavily relied upon, such as in regions supplied by irrigation canals.

Imagine pouring water into a sponge. If you keep pouring after the sponge is full, the water will simply run off the sides. Similarly, when too much water is added to soil, it cannot absorb all of it, which then causes water logging.

• Unlined or poorly lined irrigation canals and water bodies lead to seepage losses. • This seeped water accumulates underground and raises the water table. • The seepage becomes significant in areas with clayey or poorly drained soils.

When irrigation canals and ponds are not properly lined, water seeps through their walls and into the surrounding soil. This water can build up underground, particularly in areas where the soil is clayey or has poor drainage. As more water seeps in, it raises the water table and contributes to water logging.

Think of a leaky bucket placed in a bathtub. The water from the bucket seeps into the tub, filling it over time. Similarly, water from poorly managed canals seeps into the ground, causing the water table to rise.

• Lack of natural or artificial drainage systems prevents the removal of excess surface and subsurface water. • Stagnant water accumulates on the surface and within the soil profile. • In flat terrains or areas with heavy rainfall, poor drainage is a major contributor.

When there are no effective drainage systems in place—either natural waterways or artificial drains—excess water cannot escape the land. This leads to water pooling both on the surface and in the soil layers. This issue is worsened in flat areas where water cannot flow away easily, or in regions that receive a lot of rain.

Picture a towel that’s thrown in a puddle. If the towel doesn't have enough holes or is too heavy with water, it will soak up water but won’t allow any to drain out. Just like that towel, lands without drainage hold onto excess water.

• In regions with little or no land slope, water movement is restricted. • Soils with impermeable layers (like clay or hard pan) hinder percolation, causing water to accumulate above them.

In areas where the land is flat, water has a hard time moving away from where it falls. Additionally, if the soil below is made of materials that water cannot penetrate—like clay or hardpan—it causes water to pile up on top. This results in water logging as the water has no place to go.

Imagine water running into a flat tray with high sides; once it's filled up, the water can't escape. Similarly, flat land with hard subsoil holds onto water, leading to excessive saturation.

• Naturally high water tables due to geological conditions may result in water logging with minimal addition of water from external sources. • Seasonal rainfall or nearby irrigation activities can exacerbate this.

In certain regions, geological factors may lead to naturally high water tables, meaning the water is already close to the surface. When additional water from rainfall or irrigation is added, it can quickly saturate the soil, resulting in water logging.

Think of a sponge already soaked in water. Any additional water spilled onto it will just run off. Similarly, a high groundwater table means that the soil can’t absorb much additional water.

• Deforestation reduces the water-holding capacity of soil and increases runoff. • Urbanization leads to the replacement of permeable soil with impermeable surfaces, reducing natural infiltration and increasing surface accumulation.

When trees are cut down (deforestation), the soil loses its ability to hold water efficiently, leading to more water running off instead of soaking in. Similarly, in urban areas, impervious surfaces like concrete and asphalt replace natural soil, preventing water from being absorbed and leading it to accumulate on the surface.

Consider a sponge on a wooden surface absorbing water. Remove the sponge and replace the spot with a glass table; the water will simply pool on the table. Just like that, deforestation and urbanization prevent absorption of rainwater.

• Continuous cultivation of water-intensive crops (e.g., paddy) without rotation can saturate the soil profile. • Traditional flood irrigation methods waste water and raise the water table.

Monocropping refers to the practice of growing the same crop repeatedly, such as rice, which requires a lot of water. Without rotating crops to allow the soil to recover, the continued watering can saturate the soil. Additionally, older irrigation practices often lead to excess water use, which further raises the water table and compounds the problem of water logging.

It's like a kid filling the same cup with water for days without letting it dry—eventually, the cup will overflow. Just like that, repeated planting of water-heavy crops fills up the soil with water.

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