Tropical Geography ›› 2013, Vol. 33 ›› Issue (4): 496-499.

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My Opinion on Salt Tide in the Pearl River Estuary

LI Chunchu   

  • Online:2013-07-18 Published:2013-07-18

Abstract: Salt tide is designated as the low salinity (0.5-10) water body mixing salty and fresh water on landward side of the estuary. The estuary “salt water” and oceans “brine” should not be equivalent or confused. It is inappropriate to take “salt tide tracing” as “saltwater intrusion”. The salt tide tracing upstream is that the estuarine material moves with the tide movement, that is essentially a passive act. The dynamic mechanism of salt tide tracing is relevant to the circular motion process that estuarine water and salt substance move in and out with the tide, or drain and retain in a month or a day. During the period from neap tide to moderate tide (in a month ) and that at the beginning of tide ebb (in a day), estuary is in the phase from retaining (moving in) to draining (moving out). Freshwater drains at surface layer, while salt water at bottom layer, forming an obvious stratification structure. Affected by the density current, salt tide at the bottom further traces upstream rapidly, and its salinity reaches the maximum. Best result can be achieved for lowering the salinity when spring tide is transforming into moderate.

Key words: salt tide traces upstream, dynamic mechanism, fend against salt water with fresh at an opportune moment, transferring fresh water to lower the salinity, Pearl River Estuary