Flow pattern at a river diffluence at the alluvial system of the Paraná River

This communication presents field and numerical data depicting the flow pattern formed at a diffluence of the Colastiné River, Argentina, where one branch accesses the local harbour. The harbour has been in decline since the 1970s due to costly maintenance dredging of the access channel. The objective of this work is thus twofold: to show the persistence of the flow pattern developed at the diffluence despite recent morphological changes seen at the site, and to test a possible solution to the access channel sedimentation problem. Knowledge gained during the execution of the study helped to validate a code developed to process field data captured with two acoustic Doppler current profilers (ADCPs). The results confirm that both branches are prone to developing secondary currents. Simulations show that an engineering intervention downstream of the bifurcation can establish a self-dredging flow reversal along the access channel, turning the actual diffluence into a stable confluence.

本研究呈现了阿根廷科拉斯蒂内河分流口的野外实测与数值模拟数据，该分流口的一条支流通往当地港口。自20世纪70年代起，由于进港航道维护疏浚成本居高不下，该港口运营状况持续衰退。本研究的目标兼具双重性：其一，验证尽管该区域近期发生了地貌形态变化，分流口处形成的水流格局仍保持稳定；其二，针对进港航道淤积问题测试可行的解决方案。本研究过程中获取的相关认知，有效验证了一套用于处理两台声学多普勒流速剖面仪（acoustic Doppler current profilers, ADCP）采集的野外实测数据的程序代码。研究结果证实，两条支流均易形成次生环流。数值模拟结果表明，在分流口下游实施工程干预，可在进港航道形成自疏浚的水流反向格局，将该实际分流区域转变为稳定的汇流区域。