Macrotidal tropical rivers are dynamic systems where wet‐season floods and tidal flows cause significant riverbank erosion and sediment transport. This study aimed to explore patterns of riverbank erosion and deposition in a large, tropical, macrotidal river in Northern Australia; the Daly River. In particular, we aimed to determine if recreational boat use was impacting bank erosion in this dynamic river. Erosion pins were installed at multiple levels on both banks at 10 sites along a 34 km reach of the river. Measurements were made every four to six weeks during the low water dry season, and opportunistically during the wet season (flooding period) and seasonal transition periods. A bank geotechnical assessment, riverbed cross‐sections and site bathymetry were undertaken. Whilst the wet season was a period of substantial erosion (mean rate of 0.64 mm day⁻¹), the highest mean erosion rate (3.6 mm day⁻¹) was observed in the early dry season (April to May), a period of stabilizing water levels but greatest boat traffic. Bank erosion at this time was measured on both sides of the river and the inside of meander bends, which is atypical of normal riverine bank erosion patterns, and indicative of erosion due to boat wash. As the dry season progressed, significant spatial differences in erosion rates were evident, where erosion was observed at sites upstream of a large shallow sand bar, while sites downstream from the sand bar gained material through the deposition of tidally transported sediment. This study highlights the importance of understanding the significance and interaction of various erosive factors in tropical tidal rivers and has demonstrated that boat wash may be an important contributor to dry season bank erosion in these systems. We encourage management agencies to consider the role of boats in any future river management program in these systems.

中文翻译：

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潮汐热带河流的河岸侵蚀：探索洗船对河岸侵蚀的相对影响

大型潮汐热带河流是动力系统，在这些系统中，湿季洪水和潮汐流会引起河岸侵蚀和泥沙输送。这项研究旨在探讨澳大利亚北部一条大型热带巨潮河中河岸侵蚀和沉积的模式。戴利河。特别是，我们旨在确定休闲船的使用是否正在影响这条动态河流的河岸侵蚀。在这条河的34公里处的10个站点的两岸上，都在多处安装了侵蚀钉。在淡水干旱季节每四到六周进行一次测量，并在雨季（洪水时期）和季节性过渡时期进行机会测量。进行了银行岩土评估，河床横截面和工地测深。雨季是一个严重侵蚀的时期（平均率为0。^-1），最高平均腐蚀速率（3.6毫米天^-1在干旱的早期（4月至5月），水位稳定，但船流量最多。此时测量的是河两岸和弯道内侧的河岸侵蚀，这是正常河岸河岸侵蚀模式的不典型现象，并指示了因洗船而引起的侵蚀。随着干旱季节的进行，侵蚀速率的空间差异明显，在大型浅沙洲上游的站点发现了侵蚀，而沙洲下游的站点通过潮汐沉积物的沉积获得了物质。这项研究强调了理解热带潮汐河流中各种侵蚀因素的重要性和相互作用的重要性，并表明洗船可能是这些系统中旱季河岸侵蚀的重要因素。