Author(s): Fangwei Xing; Jian Sun; Yuanyi Li; Dekuai Yuan; Jianhua Tao
Linked Author(s): Dekui Yuan, Jianhua Tao
Keywords: Bohai Sea; Water exchange; Half-life Time; Age; Mathematical Model
Abstract: In Bohai Sea, which is a semi-closed sea, the water exchange is an important property for the water quality and ecosystem. The environmental pressure is further intensified with the increasing development of the economy and society in this region. What ability Bohai Sea has to accommodate the pollution load is influenced or even determined by the characteristics of the water exchange. The concepts of age and half-life time are two useful tools to describe the water transport characteristics in natural waters. In this paper, using this two time scales, the water exchange properties in Bohai Sea have been investigated based on a numerical model which includes the hydrodynamic model and convective-diffusion model. This model was verified against historical records and recent field survey investigation. The half-life times are given to present the characteristic times interval of water ’s leaving the four sub-regions, including the Bohai Bay, Liaodong Bay, Laizhou Bay and the Bohai Center. It is shown that the longest half-life time is in Liaodong Bay, about 1. 5 years, followed by Bohai Bay, about 0. 7 years while the shortest one is in Laizhou Bay about 0. 5 years. It takes a long period of 8. 5 years for the water in Bohai Bay to leave from the Bohai Sea, while for Laizhou Bay, this period is only about 2. 5 years, which is the shortest time among the three bays. In contrasts to the half-life time, age is simulated to measure the time interval of water entering Bohai Sea. The distribution of age shows that it takes difference periods for water to reach different positions in this gulf. The value of water ’s age is shortest in the Liaodong Bay, approximately 2-6 years, while it is about 10 years in Bohai Bay. The variations of half-life time and age of the water body reflect the characteristics of water exchange in various points of view, which is related to the circulation in Bohai Sea.
Year: 2013