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El-Niño/La-Niña Coastal Comparison Photography - Oregon

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Dennis Krohn
  Click on any numbered location on the map above to view the photo set and data for that location.

La-Niña Mapping, May, 1999

A Follow-on Experiment to the El-Niño Coastal Mapping, October 1997 / April 1998

In the fall of 1997 and the spring of 1998, a USGS-NASA-NOAA consortium successfully mapped 1200 km of the Pacific Coast to document coastal effects from the El-Niño storm conditions. (See lidar and aerial photography web sites). A small follow-on experiment was attempted in the spring of 1999 to document coastal changes by photography the year after the El-Niño storm season. Aerial photography is used as a reconaissance tool to see how often repeat mapping missions are required. Sea surface temperatures were abnormally cool in the spring of 1999 indicative of La-Niña conditions. In addition considerable snowpack remained on the peaks of the Cascades and Sierra Nevada mountain ranges at the time of the overflights, so additional coastal effects may have occurred after the photography was acquired.

Related Links:
» El-Niño Coastal
» El-Niño Lidar

Map of west coast El-Niño photography areas, indicated by red boxes. Area of above follow-on map of Oregon is indicated by the blue box.
A hypothesis was developed after the El-Niño missions based on the sedimentation patterns observed at the river mouths (Edgar and Krohn, 1998). The hypothesis states that precipitation seasonality is a major factor influencing sedimentation. In the 1997/1998 El-Niño storm season, the largest difference between low and high precipitation occurs in Central California, which also shows some of the largest sedimentation effects.

A sample of the La-Niña sedimentation patterns for southern Oregon can be observed here. The site showing some of the largest changes during the El-Niño missions (site 1) shows little change for La-Niña conditions. Some streams show a remigration to pre El-Niño conditions (site 2). The configuration of streams in the area blanked in 1998 by coastal fog seem to remain fairly constant as well (site 3). The one exception to this pattern of little change seems to be around the Siletz River (sites 4 and 5). A large amount of sedimentation occurs in the La-Niña conditions that were not observed pre or post El-Niño. While the cause of this sedimentation is unknown at this time, an extreme amount of rainfall was recorded in May, 1999 at the Laurel Mountain rain gauging station (Fig 1).

Photo acquisitions were attempted for the central and southern California coasts to complement this data set, but coastal fog from the La-Niña conditions prevented acquisition of more aerial photography.

Coastal and Marine Program > St. Petersburg Coastal and Marine Science Center > Research by Theme > Hazards > Hurricane and Extreme Storm Impact Studies > El-Niño/La-Niña Coastal Comparison Photography - Oregon
U.S. Department of the Interior, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center
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Updated April 15, 2014 @ 01:01 PM (THF)
Location 1 Location 2 Location 3 Location 4 Location 5 Laurel Mountain Station