Which risk most directly reduces structural lifetime of terrace farming retaining walls during seasonal torrential rains?

💡 Explanation

When torrential rains saturate the soil behind terrace retaining walls, increased hydrostatic pressure occurs because water fills pores, increasing the force on the wall leading to potential collapse. Therefore hydrostatic pressure is critical, rather than thermal expansion, root penetration, or wind, which are secondary and slower acting degradation mechanisms.

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