Which risk increases during prolonged saturation of a river levee's foundation soil?

💡 Explanation

When prolonged saturation occurs, increased pore water pressure reduces effective stress within the foundation because it counteracts the weight of the soil, potentially leading to reduction in soil's shear strength, resulting in instability. Therefore foundation failure risk increases, rather than primarily surface erosion,channel overtopping or true liquefaction which need differential shaking dynamics in addition to saturation.

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