526 



Currents in a Strait 



V, cm /sec 



20 40 60 80 



V, cm/sec 

 20 40 



. 40 



Fig. 243. Vertical current distribution in the northern part of Bosporus (to the left) and of 



the Dardanelles (to the right); H \ 1 , according to the observations; 



. — . — • — , according to the theory. 



the middle of the strait must be due to piling-up of water in the narrowest part of the 

 strait. 



Table 141. Sea surface and slope of the internal boundary surface, as well 



as frictional coejficients in the Bosphorus and the Dardanelles, 



calculated from current profiles 



Wind conditions 



{Sea surface 

 boundary 

 surface . 



Turbulent coeflRcient 



(cm^/'sec) 



Bottom friction k . 



Bosphorus 



Northern 

 part 



NE-SW 

 101 



36 



298 

 0017 



Middle 

 part 



NE.j 

 5-6 



36 



371 

 0-155 



Southern 

 part 



NE and SSW 

 2-4 cm/30 km 



36 m/30 km 



485 

 015 



Dardanelles 



Northern 

 part 



NE.3. 

 7-6 



10 



82 

 0109 



Middle 

 part 



SW 



12-2 



12 



28 

 0038 



Southern 

 part 



NE.3_, 

 7-2 cm/65 km 



19 m/65 km 



420 

 0-388 



The turbulent coefficient is of the same order of magnitude as in tidal currents. 

 The coefficient of bottom friction has a mean value of 0-12 which is very large. The 

 individual values are strongly scattered but are around 50 times larger than the values 

 found for natural channels and about 5 times larger than those found for rivers. The 

 rolls with horizontal axis produced by the very irregular bottom and which cannot be 

 observed by means of current measurements may simulate a bottom friction larger 

 than actually present. 



(h) Water Interchange Between North Sea and Baltic 



This takes place in the area between the Kattegat in the north and the Darsser and 

 Drogden ridges in the south. These give access to the Baltic at depths of 18 and 7 m, 

 respectively. The annual inflow of fresh water into the Baltic averages about 500 km^ 

 of which 467 km^ is the inflow from rivers and 206 — 1 82 = 24 km^ is the excess of 



