■with the yearly average. The UO.O^ isohaline then extends approx- 

 imately from Cape Naband northward to the delta of the Shatt. 



"Such a high salinity concentration in the Persian Gulf depends, 

 like in the Red Sea, upon the very high air temperatures and great 

 evaporation of water and upon the extremely small supply of fresh 

 water runoff. Considering this last point, one might naturally as- 

 sume that the highest salinity could he expected along the Arabian 

 coast in the deep hays of the Pirate Coast where no rivers reach 

 the sea, while along the Persian coast there are a few small rivers 

 that flow into the Gulf and besides, the Persian side . . . receives 

 quite an amount of rain, at least more than the Arabian side does. 

 However, these two factors are not decisive. Decisive is the flow 

 received frcm the sole large stream system, the Euphrates and Tigris, 

 whose quantities of fresh water due to the influence of the earth's 

 rotation ( Coriolos Force. Ed. ), flow exclusively southward along 

 the Arabian coast ( are deflected to the right. Ed. ), as might al- 

 ready have been guessed from the isotherms of the surface waters , . 

 The rxmoff from the Shatt al Arab affects the constantly present 

 strong pressure of the isohalines toward the east from the mouth, 

 where the salinity is about kO%c, while 35%, and even 30 %o appear 

 halfway between Fao and Kuwait Bay. The isohalines here, like the 

 isotherms, run from north to south instead of from west to east. 



"With these facts in mind the yearly fluctuations, especially 

 the freshening of the Gulf water in spring and early summer (May- 

 June), can be explained. In contrast to the Kile, which has its 

 high flood in October. and its low-water stand in April-May, the 

 Euphrates and Tigris taken together show their greatest runoff in 

 April at Hit and Baghdad resulting from the melting of snow in the 

 Armenian mountains. Both combined carry approximately 5^700 cubic 

 meters of water per second. In August flow has decreased, and in 

 October the combined flow of both streams returns to a minimum of 

 700 cubic meters. If we consider that the stream flow takes sev- 

 eral weeks after passing Baghdad until it reaches the Gulf, the 

 minimum salinity of the months May-June seems to fit pretty well 

 into the picture. Without the Euphrates and Tigris runoff, we 

 could analogously expect the salinity in the Persian Gulf area 

 not affected by the Indian Ocean, that is, approximately west 

 from Lingeh, to be the same as in the northern Red Sea (39^5Xo). 

 However in August-September, that is, during the period between 

 extremes, the 39.5^ isohaline runs exactly in the middle or along 

 the longitudinal axis of the Gulf from KW to SE, and the area in 

 which there is a noticeable general decrease of salinity, due to 

 the dispersion of the Shatt water, can be estimated to occupy a 

 little less than half of the Persian Gulf, that is, about 100,000 

 square kilometers. 



"It should be kept in mind that in this area, which borders 

 and is influenced by the Arabian Sea, salinities can be considered 



26 



