Effect of Rainfall on Salinity Changes in Coastal Waters

These studies showed the change process of salinity in the marine bay and the effect of rainfall on its process, which clearly explain its change reasons. By the survey data on the waters of Jiaozhou Bay in August, September and October 1980, by computing the statistical methods, in this paper studied was the horizontal distribution and regional variation of salinity in its surface waters. The results present that in August, September and October, its variation range in the waters was 24.67–31.48‰. The salinity in the water body was the lowest in August. In August, September and October, it increased in the water body. From August to October, the salinity in the northwestern coastal waters presented an upward trend and at the same time, the low-salinity zone appeared in the northwestern coastal waters transferred to the high-salinity zone. From August when the rainy season was strong to the end of the rainy season in October, a large amount of land surface runoff flowed into the coastal waters and was greatly reduced. In this way, the transport of fresh water from the surface runoff of coastal waters was transformed into a large amount of evaporation. Therefore, rainfall determined the changes in salinity of coastal waters. From August to October, the surface ocean currents existed in every month and brought high salinity to Jiaozhou Bay all the way. At the same time, the high salinity brought by surface ocean currents to Jiaozhou Bay presented an upward trend with the variation range of 31.16–31.48‰. The interval length of its changes in the seawater was 0.32‰, which indicated that the variation of high salinity brought by surface ocean currents to Jiaozhou Bay was stable. In September, in the estuary water area of Loushan River, it reached the lowest level, 30.68‰. Therefore, the fresh water transported by rivers resulted in its decreasing in the estuary water area of rivers. In September, a low-salinity zone with the salinity of 30.37‰ appeared in the southeastern wharf area, which was the only one low-salinity zone appeared in August, September and October, revealing that the discharge of ballast water from a large number of ships would also reduce the salinity of local waters.