Hydrological impacts of floodplain restoration: a case study of the River Cherwell, UK

International audienceThis paper investigates the impacts on floods of hypothetical changes to river channel geometry by construction or removal of embankments to prevent water spreading onto the floodplain at high flows. A numerical model is applied to the River Cherwell between Oxford and Banbury to simulate changes to flood hydrographs. Embanking the river increases the peak flows downstream by 50-150%. Restoring the river channel through the floodplain to pre-engineered dimensions reduces peak flow by around 10-15% and increases peak water levels within the floodplain by 0.5-1.6 m. These results suggest that floodplain rehabilitation, in terms of embankment removal or returning the channel to pre-engineered dimensions, can be a valuable part of the flood management strategy of a catchment. Both measures lead to increased inundation of the floodplain, which can be positive for ecological restoration. Keywords: floodplains, hydrological impacts, rehabilitation, flood frequenc

Characterization of the cyclic behavior of dry masonry joints

Dry masonry mechanics received little attention from research community, when compared with resources invested in traditional (mortar joint) masonry. Nevertheless, a large number of historical stone constructions use dry masonry joints, while, in constructions originally built with weak lime mortar, mortar deterioration leads to a behavior similar to dry masonry. Therefore, the objective of this paper is to contribute to the knowledge of the behavior of dry masonry joints under cyclic loading, which is a key aspect for seismic actions. The work focuses on the characterization of Coulomb failure criterion and the load-displacement behavior of dry masonry joints under cyclic loading, including aspects as surface roughness, dilatancy and inelastic behavior. A displacement controlled test set-up using masonry couplets is used for this purpose. Besides providing a basis for understanding the behavior of masonry joints in tension, the experiments contribute also to the definition and parameterization of advanced non-linear numeric models

Among‐species variation in six decades of changing migration timings explained through ecology, life‐history and local migratory abundance

We thank all Fair Isle residents for their long-term support, and W.T.S. Miles and I.J. Andrews for database construction and management. V.R.D was funded by a UK NERC SUPER DTP PhD studentship supported by University of Aberdeen and Fair Isle Bird Observatory Trust.Species exploiting seasonal environments must alter timings of key life‐history events in response to large‐scale climatic changes in order to maintain trophic synchrony with required resources. Yet, substantial among‐species variation in long‐term phenological changes has been observed. Advancing from simply describing such variation towards predicting future phenological responses requires studies that rigorously quantify and explain variation in the direction and magnitude of changing timings across diverse species in relation to key ecological and life‐history variables. Accordingly, we fitted multi‐quantile regressions to 59 years of multi‐species data on spring and autumn bird migration timings through northern Scotland. We demonstrate substantial variation in changes in timings among 72 species, and tested whether such variation can be explained by species ecology, life‐history and changes in local abundance. Consistent with predictions, species that advanced their migration timing in one or both seasons had more seasonally restricted diet types, fewer suitable breeding habitat types, shorter generation lengths and capability to produce multiple offspring broods per year. In contrast, species with less seasonally restricted diet types and that produce single annual offspring broods, showed no change. Meanwhile, contrary to prediction, long‐distance and short‐distance migrants advanced migration timings similarly. Changes in migration timing also varied with changes in local migratory abundance, such that species with increasing seasonal abundance apparently altered their migration timing, whilst species with decreasing abundance did not. Such patterns broadly concur with expectation given adaptive changes in migration timing. However, we demonstrate that similar patterns can be generated by numerical sampling given changing local abundances. Any apparent phenology‐abundance relationships should, therefore, be carefully validated and interpreted. Overall, our results show that migrant bird species with differing ecologies and life‐histories showed systematically differing phenological changes over six decades contextualised by large‐scale environmental changes, potentially facilitating future predictions and altering temporal dynamics of seasonal species co‐occurrences.Peer reviewe

New Insight in Loss of Gut Barrier during Major Non-Abdominal Surgery

PG - e3954 AB - BACKGROUND: Gut barrier loss has been implicated as a critical event in the occurrence of postoperative complications. We aimed to study the development of gut barrier loss in patients undergoing major non-abdominal surgery. METHODOLOGY/PRINCIPAL FINDINGS: Twenty consecutive children undergoing spinal fusion surgery were included. This kind of surgery is characterized by long operation time, significant blood loss, prolonged systemic hypotension, without directly leading to compromise of the intestines by intestinal manipulation or use of extracorporeal circulation. Blood was collected preoperatively, every two hours during surgery and 2, 4, 15 and 24 hours postoperatively. Gut mucosal barrier was assessed by plasma markers for enterocyte damage (I-FABP, I-BABP) and urinary presence of tight junction protein claudin-3. Intestinal mucosal perfusion was measured by gastric tonometry (P(r)CO2, P(r-a)CO2-gap). Plasma concentration of I-FABP, I-BABP and urinary expression of claudin-3 increased rapidly and significantly after the onset of surgery in most children. Postoperatively, all markers decreased promptly towards baseline values together with normalisation of MAP. Plasma levels of I-FABP, I-BABP were significantly negatively correlated with MAP at (1/2) hour before blood sampling (-0.726 (p<0.001), -0.483 (P<0.001), respectively). Furthermore, circulating I-FABP correlated with gastric mucosal P(r)CO2, P(r-a)CO2-gap measured at the same time points (0.553 (p = 0.040), 0.585 (p = 0.028), respectively). CONCLUSIONS/SIGNIFICANCE: This study shows the development of gut barrier loss in children undergoing major non-abdominal surgery, which is related to preceding hypotension and mesenterial hypoperfusion. These data shed new light on the potential role of peroperative circulatory perturbation and intestinal barrier los

Some aspects of the dispersal and post-fledgling ecology of a population of Great Tits (Parus major)

SIGLEAvailable from British Library Document Supply Centre- DSC:D170188 / BLDSC - British Library Document Supply CentreGBUnited Kingdo