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PurposeA disconnected ephemeral tributary was reconnected to the regulated River Ehen (NW England) as part of a riverrestoration initiative, providing a renewed delivery of sediment to a highly stable and armoured channel. This paper (1) assessesspatial and temporal dynamics of suspended and stored sediments in the Ehen, (2) characterises the composition of storedsediment, (3) develops fine sediment budgets for downstream river reaches, and (4) assesses the controls on the storage of finesediment in the riverbed.Materials and methodsA 3-km study section in the upper part of the River Ehen was divided into two reaches. Suspendedsediments were monitored at the downstream limits of each reach over a 2-year period. In-channel storage was measured in threemorphological units within the upper reach, on 13 occasions over the same period. Samples were used to assess changes involumes of stored fine sediment, as well as the grain sizes and organic content of the material. A time-lapse camera facing theconfluence of the tributary was used to conceptualise different flow scenarios. These scenarios reflect the degree of synchronicitybetween flows in the main-stem and those in the tributary. Fine sediment budgets were developed for each reach to assess therelative contribution of different sources of sediment.Results and discussionThe reconnection significantly affected suspended sediment loads in the Ehen. Bed storage increasedtwofold, with changes most evident in the slow-flowing morphological unit. Changes in the composition of stored sediment wereless marked than changes in the quantity of material. Changes in bed storage were controlled by the degree of synchronicitybetween flows in the Ehen and those in the newly reconnected tributary. Results show that three generalised flow scenarios occur,with total asynchronicity between flows in the tributary and the Ehen being responsible for the main episodes of fine sedimentdeposition. Overall, the estimated sediment budgets provide insights into the importance of non-perennial sources of sediment insupply-limited systems such as the Ehen. Although bed storage values are within the range of those published for UK rivers, theincrease observed since the reconnection, together with the persistence of a static pavement, highlights the ecologically criticalconditions of the regulated main-stem River Ehen.ConclusionsIntermittent sources control fine sediment transport dynamics in the upper River Ehen. In this regulated river,ongoing deposition associated with increased low- and medium-sized flow events exerts more of a control on bed storage thanlarge but rare floods. Management actions to limit delivery of material from lateral sources could help prevent further deterio-ration of habitat conditions for biota sensitive to fine sediment. Given the ongoing adjustment in the newly reconnected tributary,continued monitoring is needed to capture further morphosedimentary response in the main-stem.This study was funded by the Environment Agency (EA) and United Utilities (UU) as part of a PhD grant. We would like to thank Gail Butteril, Jane Atkins, Andy Newton and Helen Reid from EA, as well as Kat Liney and Grace Martin from UU for their help and support throughout the project. Damià Vericat is funded by a Ramon y Cajal fellowship (RYC-2010-06264). Authors acknowledge the support from the Economy and Knowledge Department of the Catalan Government through the Consolidated Research Group B Fluvial Dynamics Research Group ^ — RIUS (2014 SGR 645), and the additional support provided by the CERCA Programme, also from the Catalan Government. We are also thankful to two anonymous reviewers whose comments have helped improve the paper

Asynchronicity of fine sediment supply and its effects on transport and storage in a regulated river