Geomorphic Effects of Stream Channelization on The Rio Puerco Near La Ventana, New Mexico, USA
— Kevin M. Hobbs

In 1965, the New Mexico Department of Transportation channelized a 3.4-km section of the Rio Puerco near La Ventana,
Sandoval County, New Mexico, with an artificial, straight 1.7-km-long channel to facilitate new highway construction. The channelization
nearly doubled the slope of the stream while reducing the hydraulic radius of the channel. Geomorphic adjustments in the channelized
reach were drastic and rapid, including incision, widening, and development of meanders. In 2006, after the channelized reach had incised
to depths of at least 15 m, widened to at least 105 m, and developed a meander that threatened U.S. Route 550, the river was rerouted back
into its natural channel. During the four-decade lifespan of the channelization, an estimated 6.2 × 105 m3 of sediment was removed via
erosion and delivered down the Rio Puerco. The sinuosity of the channelized reach increased from 1.000 to 1.093. Headward migration of
a knickpoint in the channelized reach was retarded only by the presence of resistant bedrock underneath alluvium. A 1997 geological investigation
of the then-active channelization accurately estimated sediment removal and predicted future geomorphic responses that were later
observed. Geomorphic adjustments in the channelized reach and the Rio Puerco’s natural channel continue at present and include stream
slope adjustment in the natural channel, channel widening due to bank collapse, and development of soil piping leading to considerable
sediment transport and likely perpetuating arroyo widening. The changes to the Rio Puerco fluvial system caused by the channelization will
continue into the future until the river reaches new geomorphic equilibrium.