Both faces of an embankment dam must be protected against structural damage. In normal circumstances the downstream will only be subject to the forces of nature. The upstream face must be protected against erosion or disturbance by wave action, ice or by impact of floating debris. Various methods of protection include large rocks (rip-rap), precast concrete forms, soil cement or the waterproofing membrane of the dam. Protection must be well above and below the operating range of the reservoir.
Soil Cement Slope Protection
Rip-rap size : Mass of individual rock = 1000 x (Wave Height Hs)3 (kg)
The rip-rap must be durable, weatherproof and of good quality sound rock to enable it to withstand the changing harsh conditions.
(C) Thomas, Henry H. The Engineering of Large Dams