I traveled a hundred miles along the river, setting up sieves amidst the waves at various points to examine th…
I traveled a hundred miles along the river, setting up sieves amidst the waves at various points to examine the changes in sediment and currents.
My findings: the surface of the river flows swiftly, while the riverbed moves slowly. Where the river winds, the concave bank is deep and rapid, whereas the convex bank is shallow and gentle. Between the concave and convex, there are backflows that churn the silt, depositing it upon the convex shore. The "Flying Fish" weir of Dujiangyan utilizes this very principle to separate sand, and it is indeed effective.