Paper No. 39-4
Presentation Time: 2:35 PM
FOREDUNE GROWTH ENHANCED BY EUROPEAN BEACH GRASS IN OREGON - IMPORTANT NATURAL TSUNAMI BARRIERS
Foredunes are an important part of beach systems. Along the coast in Oregon and Washington, they are growing because of the introduction of European Beach Grass in the 1930's to stabilize dunes. The grass is everywhere today. Before the 1930's the foredunes were low with a maximum size of 2 m and the major sand spits along the Oregon coast were a maximum of 3-4 meters high. Today, the foredunes are up to 20 m hight and the spits have dunes on them up to 25 m elevation. The grass entraps sand blown off of the beaches and grows upward thereby increasing dune height and stabilizing it. Foredunes have become natural barriers along the coast protecting homes in back, especially from winter storm surges and distant tsunamis which can get up to 2-3 meters high. I have completed a 45 year study on foredunes on the Salishan Spit near Lincoln City, Oregon. They have grown approximately 7 cm/yr during that period of time. I recomend that homes along the coast do not knock down these new large dunes in order to see the beach from the homes. One is losing Mother Nature's protection barrier from storm surges and distant tsunamis.