Mapping Flow‐Obstructing Structures on Global Rivers

To help store water, facilitate navigation, generate energy, mitigate floods, and support industrial and agricultural production, people have built and continue to build obstructions to natural flow in rivers. However, due to the long and complex history of constructing and removing such obstructions, we lack a globally consistent record of their locations and types. Here, we used a consistent method to visually locate and classify obstructions on 2.1 million km of large rivers (width ≥30 m) globally. We based our mapping on Google Earth Engine’s high resolution images, which for many places have meter‐scale resolution. The resulting Global River Obstruction Database (GROD) consists of 30,549 unique obstructions, covering six different obstruction types: dam, lock, low head dam, channel dam, and two types of partial dams. By classifying a subset of the obstructions multiple times, we are able to show high classification consistency (87% mean balanced accuracy) for the three types of obstructions that fully intersect rivers: dams, low head dams, and locks. The classification of the three types of partial obstructions are somewhat less consistent (61% mean balanced accuracy). Overall, by comparing GROD to similar datasets, we estimate GROD likely captured >90% of the obstructions on large rivers. We anticipate that GROD will be of wide interest to the hydrological modeling, aquatic ecology, geomorphology, and water resource management communities. Plain Language Summary Many obstructions (e.g., dams and locks) have been built on rivers across the globe to help store water, facilitate navigation, generate energy, mitigate floods, and support industrial and agricultural production. However, the lack of publicly available information on where these obstructions are reduces our ability to assess their environmental impact. In this study, we used publicly available satellite data from Google to manually identify river obstructions on all large rivers across the globe (width ≥30 m) to develop the Global River Obstruction Database, or GROD. GROD consists of 30,549 unique obstructions assigned to one of the six types: dam, low head dam, lock, channel dam (a dam that obstructs one channel of a multi‐channel river), and two types of partial dams (dam that extends partially across a river). By repeatedly classifying subsets of GROD obstructions, we estimate high classification consistency. And by comparing GROD to five other obstruction datasets, we estimate that GROD