Coastal Erosion in Southern California Enhanced by the El Niño By Zachary Moody

Outline  Background on Erosion  Background on El Niño  Measuring Coastal Erosion  LiDAR Technology  Case Examples from  Human Involvement

Typical California Coastline

El Niño

El Niño Global Effects  Began earlier than normal and peaked in January  Temperatures >4 o than normal in eastern Pacific and in some areas >9 o  Drought and wildfires in Indonesia  Increased number of hurricanes off of Mexico’s coast  2100 deaths and $33 billion in property damage worldwide

El Niño Effects in the United States  Killer tornadoes in the Southeast U.S.  Massive blizzards in the upper Midwest U.S.  Flooding in the Ohio river valley  California received 2x the normal rainfall which caused flooding and landslides El Niño related landslides along the California coast.

El Niño Impacts Larger and More Violent Storms  More Powerful Waves  Greater Coastal Erosion

Measuring Coastal Erosion Methods:  Surveys  Aerial Photography  Light Detection and Ranging (LiDAR)

LiDAR  Scanning Laser  Stream of Light Pulses Emitted Side-to-Side  Acquires Location and Elevation Data  GPS Receivers and Satellites used to indicate location as data is collected

LiDAR Advantages  Saves Time, Money, and Manpower  Greater Coverage Area  Water Depth Information  Integrated with GPS/GIS  Capable of mapping steeped sloped regions, shadowed areas, and inaccessible areas (such as mud flats and ocean jetties).

El Niño Effects in Southern California

Monty Hampton, USGS January, 1998 February 1998

Sea cliffs in Pacifica, CA  13 meters of cliff erosion in one year  El Niño accounted for about 50 years of cliff erosion at this location  12 houses were condemned  7 were undercut and fell into the ocean

Southern Pacifica Northern Pacifica

Analyzing LiDAR Data Landslides Longshore Transport Overwash River Breakthrough

San Diego 1

2 October, 1997 April,

San Diego 3

Ventura 1

2 October, 1997 April,

Human Interaction  Erosion is a natural process that is inevitable. Humans can intervene but this only deters erosion to alternate areas.  Examples -Jetties-Seawalls-Groins -Beach Renourishment

Questions? Sources  Griggs, G.B. (2002). Coastal Cliff Erosion in San Diego County. Sea Grant California Coastal Ocean Research, R/CZ-157:  Sallenger Jr. A.H. et al. (2002). Sea-cliff erosion as a function of beach changes and extreme wave runup during the El Niño. Marine Geology 187, no.3-4 p  Storlezzi C.D. and Griggs G.B. (2000). Influence of El Niño-Southern Oscillation (ENSO) events on the evolution of Central California's shoreline. Bulletin of the Geological Society of America 112, no.2 p  (2/20/07)  (2/20/07)  (2/20/07)  (2/20/07)