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Why must irrigation projects include drainage systems?
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Irrigation
Specialized irrigation equipment watering crops in a field.
Irrigation projects must include drainage systems to ensure the long-term productivity of agricultural land and to prevent soil degradation. The primary reasons for this necessity include:12
- Salinity Control: Irrigation water naturally contains dissolved salts. As water evaporates from the soil, these salts accumulate in the root zone. If left unchecked, this high salinity inhibits plant growth by causing dehydration and preventing nutrient uptake. Drainage systems allow for the leaching of these salts by flushing the soil with excess water, which is then carried away through the drainage network.3425
- Water Table Management: In many irrigated areas, the application of water can cause the water table to rise to levels that harm crop development. Subsurface drainage systems are essential for controlling the water table, ensuring that water can move through the soil profile rather than stagnating.5
- Sustained Productivity: Irrigation and drainage are often required together to maintain high-level crop production. While irrigation provides necessary moisture, drainage prevents the negative consequences of waterlogging and salt buildup, which would otherwise render the land unproductive over time.145
By managing water movement and salt balance, drainage systems protect the soil environment and ensure the viability of irrigated agriculture.35