Tidal irrigation is the subsurface irrigation of levee soils in coastal plains with river water under tidal influence. It is applied in (semi) arid zones at the mouth of a large river estuary or delta where a considerable tidal range (some 2 m) is present. The river discharge must be large enough to guarantee a sufficient flow of fresh water into the sea so that no salt water intrusion occurs in the river mouth.^[1]

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The irrigation is effectuated by digging tidal canals from the river shore into the main land that will guide the river water inland at high tide.^[1]

For the irrigation to be effective the soil must have a high infiltration capacity to permit the entry of sufficient water in the soil to cover the evapotranspiration demand of the crop.^[1]

At low tide, the canals and the soil drain out again, which promotes the aeration of the soil.^[1]

• Tidal irrigation at Abadan island, Iran