Determination of water renewal rates in the Paranaguá estuarine complex

ABSTRACT This work investigates the water renewal in the Paranaguá Estuarine Complex (PEC), located in the state of Paraná, Brazil, using the SisBaHiA® computer modelling system. A hydrodynamic circulation model, for the definition of hydrodynamic circulation patterns, and an Eulerian transport model, for the computation of the water renewal rate, water age and residual circulation, were implemented. The water renewal rate, water age and residual circulation were computed for different hydrodynamic scenarios, with representative summer and winter periods and, consequently, with different forcings (tide, river flow or wind), in order to identify possible stagnation areas. Results show that the tide and the river flows are the most important forcings in the water renewal of the PEC. Two possible stagnation areas were identified in all scenarios, which presented lower renewal rates and higher water ages when compared to the other regions, namely, the Pinheiros bay region and the region near to Paranaguá city. During the summer and taking into account all the forcings, renewal rates in the Pinheiros Bay region and near the city of Paranaguá are less than 95% whereas in the other regions of the PEC, the values are higher than 95%.

摘要 本研究采用SisBaHiA®计算机建模系统，对位于巴西巴拉那州的巴拉那瓜河口复合体（Paranaguá Estuarine Complex, PEC）的水体更新过程开展研究。研究构建了用于确定水动力环流格局的水动力环流模型，以及用于计算水体更新速率、水体年龄与余流的欧拉输运模型。针对包含典型夏季与冬季时段的不同水动力情景（各情景配置有不同强迫力：潮汐、径流或风力），研究计算了水体更新速率、水体年龄与余流，以识别潜在滞流区域。结果表明，潮汐与径流是巴拉那瓜河口复合体水体更新的最主要强迫力。所有情景中均识别出两处潜在滞流区域，相较于其他区域，这两处区域的更新速率更低、水体年龄更高，分别为皮涅鲁斯湾（Pinheiros Bay）区域与巴拉那瓜市周边区域。在夏季且考虑全部强迫力的情景下，皮涅鲁斯湾区域及巴拉那瓜市附近区域的水体更新速率均低于95%，而巴拉那瓜河口复合体其他区域的更新速率则高于95%。