Qualitative evaluation of rock weir field performance and failure mechanisms

River spanning loose-rock structures provide sufficient head for irrigation diversion, permit fish passage over barriers, protect banks, stabilize degrading channels, activate side channels, reconnect floodplains, and create in-channel habitat. These structures are called by a variety of names including rock weirs, alphabet (U-, A-, V-, W-) weirs, Jhooks, and rock ramps. These structures share the common characteristics of:

1. Loose rock construction materials (individually placed or dumped rocks with little or no concrete);
   
2. Extents spanning the width of the river channel; and
   
3. An abrupt change in the water surface elevation at low flows.