Research Task: 8327CKY.4.0
Task Manager: Pat Shafroth
Managers of riparian lands across the West seek to remove stands of the invasive shrub, tamarisk (Tamarix spp., or saltcedar), for purposes such as reducing water lost to evapotranspiration, improving wildlife habitat, or restoring native vegetation. However, removing what is now the dominant riparian tree in the Southwest could have unintended consequences, including accelerated erosion; indeed, stabilizing sediment was a primary rationale for the original introduction of tamarisk. Many of the streams currently targeted for tamarisk control could become geomorphically unstable if the woody vegetation is removed, and subsequent floods could cause substantial sediment erosion and transport, potentially increasing flood hazards for communities downstream and accelerating the filling of reservoirs with sediment. Despite these risks, the effect of tamarisk control on erosion has received little attention. Much of the tamarisk is on Tribal lands, whose managers must balance the need for water and traditional wildlife habitat with concerns about erosion and herbicide application. The overall objectives of this task are to (1) document the changes in channel geometry resulting from tamarisk removal along the Rio Puerco west of Los Lunas, New Mexico; (2) document channel change at a site in the Southwest where tamarisk has been removed and subsequent high flows have already occurred, and (3) enhance our existing hydraulic model for the Rio Puerco to calculate the effect of tamarisk removal on flood attenuation and sediment transport.
For more information contact Pat Shafroth