Feishayan

Feishayan, or the Flying Sand Weir, is a long, low-lying dike that stretches about two hundred forty meters along the bank of the inner river within the Dujiangyan Irrigation System. It appears as a modest, simple stone structure, yet it acts as the primary safety valve for this ancient, two-thousand-year-old engineering marvel. When floodwaters rise or sediment builds up, this spillway automatically diverts the excess volume and debris away from the irrigation channel and back into the main river flow.