MUNCH* PETERSEN'S LITTORAL DRIFT FORMULA 



Professor T.funch-Petersen carried on research in the field of 

 material drift along the ocean coasts for nearly 4-0 years. As a young 

 engineer working with the Ifanicipal ViTater-building Service in Thyboron 

 he studied this important question in cooperation with his two close 

 friends. Engineer Palle Bruum and Harbor Engineer P, Vedel, Vedel 

 became interested in the idea of the two engineers,, that it is wave 

 energy and not the ordinary ocean currents , that is the chief cause of 

 material drifting along ocean coasts. Ifr. Vedel held this view when 

 he wrote his excellent paper regarding island harbors » 



Professor Jfunch-Petersen wishes to share the honor with his two 

 late friends for development of the theory in its first form, Howevsr, 

 the following development of the theory must be credited to Professor 

 TAinch-Petersen alone . The first theory was made public at the Baltic 

 Engineer Congress in Malmo, Sweden, in I914.0 lifunch-Petersen's formula 

 when applied to different coasts has given results which are consist- 

 ent with direct observations, and abroad, as well as in Denmark, it 

 has been recognized as the best theory for predetermination of sand 

 drift at project sites on sand-drift coasts o 



Material drift along the ocean coast is defined as the movetrent 

 of coastal material (stone, gravel, sand and clay, etCo), which 

 can be observed directly, or through successive measurements at re- 

 latively short periods of time. The material drift defined above, 

 does not include the bottom material drifting at great depths under 

 the influence of different kinds of currents such as tide and other 

 gravitation currents, temperature currents, salinity currents, T;ind 

 currents, etc. In the long run, these currents have a rather great 

 influence on the coasts, and are not without interest, but acr a rule 

 their effect is subordinate in comparison to the material drift which 

 occurs along the coasts. Furthermore, it is very seldom possible 

 to control the bottom material moving at great depths, and consequent- 

 ly, this movement does not interest the engineer so much as the coast- 

 al material drift. In general the currents caused by the wind do not 

 have any influence upon the material drift along the Danish coasts, 

 although these currents are of a greater importance than the deep- 

 water currents o The primary cause of coast material drift is the wave 

 movement and associated wave currents. 



In connection with the problem of material drift, it is essen- 

 tial to find out how the waves affect the coast when they approach 

 it. There are two main kinds of waves, deep-water waves and ground- 

 water waves. In certain respects, these kinds of waves are of a 

 quite different nature . 



The deep-water wave, or the wave which turns in circles (tro~ 

 choidal), is the v«ave which occurs m deep water after leaving 



