Are national barrier inventories fit for stream connectivity restoration needs? A test of two catchments

Abstract

AbstractCatchment‐scale river reconnection programmes require barrier inventories for restoration planning, yet barrier inventories are variable in extent and quality internationally. To test the degree to which barrier databases, in this case for England, are fit for purpose, we made a comparison of the national database (mostly originating from desk‐study) for two catchments, the Wear and the Tees, against detailed walkover surveys. We surveyed 701 km (32.8%) of stream length, stratified by stream order, altitude and subcatchment and recorded natural and artificial barriers. Only 22.7% of barriers identified in the walkover survey were present in the national database, including low‐head (<5 m) artificial structures (32.3% representation), artificial barriers ≥5 m (14.3% representation) and culverts (0% representation). About 18.9% of artificial barriers in the national database were found, during a field survey, to have been breached naturally. Mean densities of artificial barriers were 0.68 barriers km−1 and 0.45 barriers km−1 in the Wear and Tees, respectively, significantly higher than in the national database. Stream connectivity restoration in England may be hampered by the incomplete national barrier inventory; we recommend careful checks of barrier inventories as they are developed internationally.