Beauty, but at what cost? Ornamental weirs fragment China's streams

In rivers across China, ornamental weirs are being installed to facilitate rural revitalization and promote eco‐tourism. Despite the goal of improving landscape aesthetics, these structures have ecological impacts—particularly on river connectivity—that may be substantial but are largely undocumented. In this study, we use Chinese social media and high‐resolution satellite images to quantify river fragmentation caused by ornamental weirs. These structures are present in at least 87 sub‐basins across China and result in intensive river fragmentation, with a median density of 0.95 barriers per kilometer and a dendritic connectivity index of 18.0 (95% confidence interval: 10.0–21.0). Notably, as compared with large dams, ornamental weirs occur in significantly higher densities and cause greater reductions in connectivity. While landscape aesthetics undoubtedly benefit local tourism, developers of ornamental weirs should seek not to jeopardize effective river connectivity, which supports the freshwater biodiversity and fisheries on which local communities depend.