The findings of research conducted under this project are presented in NCHRP Report 533, "Handbook for Predicting Stream Meander Migration,"
NCHRP Web Document 67, "Final Report-Methodology for Predicting Channel Migration,"
and accompanying CRP-CD-48, and CRP-CD-49. NCHRP Report 533 presents, in the form of a handbook, an empirical methodology developed for predicting stream meander migration. NCHRP Web Document 67 consists of a final report documenting the entire research effort for Project 24-16.
Rivers prone to channel migration may be spanned by static structures and paralleled by fixed highway alignments and appurtenances. Channel migration (alluvial river meander, platform deformation) is a major consideration in designing bridge crossings and other transportation facilities in affected areas; it causes the channel alignment and approach conditions present during construction to deteriorate as the upstream channel location changes. Channel migration can result in the following: (a) excess bridge pier and abutment scour, (b) threats to bridge approaches and other highway infrastructure, (c) worsened debris problems, and (d) obstructed conveyance through bridge openings.
Channel migration is typically an incremental process. On meandering streams, the problem at a bridge site may become apparent two or three decades after the bridge is constructed. Channel migration is often evident throughout large sections of a drainage basin; it is not localized in the vicinity of a bridge. It is a natural phenomenon that occurs in the absence of specific disturbances, but may be exacerbated by such basin-wide factors as land use changes, gravel mining, dam construction, and removal of vegetation. Remedial action such as constructing guide banks or installing bank protection becomes increasingly expensive or difficult as the channel migrates. A methodology is needed to evaluate the potential for channel movement and predict future channel migration with and without the installation of appropriate countermeasures.
The research conducted under this project resulted in the development of a practical methodology to predict the rate and extent of channel migration (i.e., lateral channel shift and down valley migration) in proximity to transportation facilities. The methodology enables practicing engineers to evaluate and determine bridge and other highway facility locations and sizes and ascertain the need for countermeasures considering the potential impacts of channel meander migration over the life of a bridge or highway river crossing.
Research is complete.
As a result of the research conducted under NCHRP Project 24-16, three research products are available:
1) NCHRP Report 533: Handbook for Predicting Stream Meander Migration
. This report is the Task 9 photo comparison handbook referenced above. The handbook describes the application of the stream prediction methodology developed and provides illustrated examples for applying the methodology. NCHRP Report 533
includes a CD-ROM (CRP-CD-48) that contains an Arc View-based data logger and channel migration predictor.
2) The contractor's final report for NCHRP Project 24-16 is available as NCHRP Web Document 67: Final Report-Methodology for Predicting Channel Migration.
3) A companion product to NCHRP Web Document 67
, a four-set CD-ROM that contains all meander site data acquired for this research. The database includes 141 meander sites containing 1,503 meander bends on 89 rivers in the United States and will be of particular interest to those conducting research in the area of stream meander migration.