ALBERT

Description: 〈p〉Publication date: Available online 28 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology〈/p〉 〈p〉Author(s): V.K.E. Duvat, V. Pillet, N. Volto, H. Terorotua, V. Laurent〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉While the geomorphic impacts of extreme climate events, including in particular tropical cyclones and distant-source swells, on atoll islands are widely acknowledged, the influence of moderate climate events, such as tropical lows that do not reach the cyclone stage and low-magnitude distant-source swells, has to date been overlooked. Based on multi-date image analysis and field observations, the geomorphic impacts of a moderate climate event, tropical low 13F (February 2017), were assessed in the northern part of Fakarava Atoll, northwestern Tuamotu Archipelago, in French Polynesia. Results show that this event, which generated strong swells, predominantly caused shoreline retreat (noted along 54.14% of transects, with the minimum Net Shoreline Movement reaching −45.46 m) along the highly-exposed shoreline section, while the rest of the shoreline predominantly exhibited stability. The effects of this swell event were mainly constructional, as shown by the formation of two small storm ramparts and of extensive sediment sheets and tracts on the conglomerate platform. In low-lying areas, the waves crossed over the islands from ocean to lagoon, depositing sediment inland. The erosional impacts of the storm waves and overwash-induced sediment deposition were lower along shoreline exhibiting high vegetation density. One year after the event, intertidal sediment deposits had significantly migrated landward. This study, which reveals an important research gap in atoll geomorphic studies, calls for the more systematic assessment of the geomorphic impacts of moderate climate events on atoll islands, especially in atoll regions that are located outside the cyclone belt (e.g. Tuamotu, Maldives, etc.), where such events can be hypothesised to be more influential than extreme climate events.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 28 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): Daniel E. Hewitt, Timothy M. Smith, Vincent Raoult, Matthew D. Taylor, Troy F. Gaston〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Estuaries represent highly important nursery habitats for a range of species, with refuge and nutrition being two key benefits derived from estuaries. Quantifying these benefits provides us with a means for enhancing fisheries productivity. 〈em〉Metapenaeus macleayi〈/em〉 (School Prawn) and 〈em〉Penaeus plebejus〈/em〉 (Eastern King Prawn) are two commercially and recreationally important species in New South Wales that utilise estuarine nurseries throughout their life history. In this study, stable isotopes of carbon, nitrogen and sulfur were used to determine the proportional contribution of primary producers to prawn nutrition in Brisbane Water (NSW). Both the saltmarsh grass 〈em〉Sporobolus virginicus〈/em〉 and seagrass 〈em〉Zostera muelleri〈/em〉 were found to support a high trophic contribution to prawns (up to 53% and 40%, respectively). The contributions of other primary producers such as mangroves, fine benthic organic matter (FBOM) and C〈sub〉3〈/sub〉 saltmarsh plants were generally found to be much lower (0.7–15%). Such findings are generally consistent with patterns observed in other south-east Australian estuaries, however such a dominant role of saltmarsh in the presence of seagrass is a novel finding. These results highlight linkages between habitats of conservation concern and highly valuable fisheries species, and the benefit of using sulfur as an additional marker in Bayesian mixing models examining mixing in estuary food webs.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 27 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): Lanli Guo, Yongsheng Wu, Charles G. Hannah, Brian Petrie, David Greenberg, Haibo Niu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The dynamics of M〈sub〉2〈/sub〉 and K〈sub〉1〈/sub〉 ocean tides in the Canadian Arctic Archipelago (CAA) have been investigated using a three-dimensional hydrodynamic model, which uses an unstructured mesh with a horizontal resolution ranging from 0.5 km in narrow channels to 10–40 km in the open ocean. The model is evaluated against observed tidal elevations and tidal currents, and the evaluation indicates that the model is able to reproduce the observations at the tidal gauge sites, particularly those in the narrow straits of the CAA. In order to examine the interactions between the Arctic and the Atlantic tides in the CAA, idealized experiments were conducted by considering tidal effects through the open boundary on the Arctic and the Atlantic sides separately. The results show that the Atlantic tide is strong throughout the CAA but deceases rapidly when it encounters the open Arctic shelf for both M〈sub〉2〈/sub〉 and K〈sub〉1〈/sub〉 tides; on the other hand, the Arctic tide is mainly confined to the Arctic Ocean and Amundsen Gulf; it has a minor influence in the Baffin Bay. Nonlinear interactions between the Arctic and Atlantic tides are generally weak except local areas in the southern and northern CAA, where the nonlinear contribution is able to reach 10–20% of the tidal variability. Using the model results, the tidal energy flux was also analyzed, and the analysis indicated that the Lancaster Sound and Jones Sound are main pathways of the tidal energy from the Baffin Bay to the CAA, and the energy is dissipated due mainly to the vertical diffusion and the bottom friction.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 28 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): Wei Zhong, Longhai Zhu, Ping Dong, Rijun Hu, Jianzheng Wu, Yingtao Zhu, Haiqin Duan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This paper investigates sediment trapping in coastal embayments during summer seasons based on observation data obtained from two instrumented tripods that were placed at the mouth of Weihai Bay on north coast of Shandong Peninsula, China, over a 15-day period between 5 and August 20, 2018. The data consisted of time series of water depths, current profiles, wave parameters, near-bed flow velocities, turbidity, water salinity and temperature. Distributions of suspended sediment concentration (SSC) and water temperature in the bay and adjacent sea areas were also investigated at 87 grid stations from July 31 to August 4, 2018. From these data the bed shear stresses, residual currents and suspended sediment fluxes (SSF) were calculated. The results indicated that the variability in the SSC at the northern mouth was mainly controlled by local sediment resuspension while at the southern mouth horizontal advection due to the SSC gradient was the dominant mechanism. To identify the main drivers of the sediment transport, the SSF was analyzed using the decomposition method. The seaward advective transport due to residual flow and landward tidal pumping effect dominated the total near-bed sediment transport at the northern and southern mouths, respectively. Therefore, trapping processes occurred mainly through the southern mouth. The suspended sediment fluxes (SSF) during neap and spring tides at the southern mouth were 0.053 and 0.321 g m〈sup〉−2〈/sup〉 s〈sup〉−1〈/sup〉, respectively, while during moderate wave conditions (H〈sub〉s〈/sub〉 〉 0.8 m), the SSF was two times larger than the spring tide. In summer, the fine-grained sediments trapped in the bay were mainly derived from resuspension off the eastern tip of the Shandong Peninsula and thus is indirectly from the Yellow River. During such sediment transport and trapping processes, upwelling and winds can also play important roles.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 27 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology〈/p〉 〈p〉Author(s): G. Sofia〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In recent years, the wealth of technological development revolutionised our ability to collect data in geosciences. Due to the unprecedented level of detail of these datasets, geomorphologists are facing new challenges, giving more in-depth answers to a broad(er) range of fundamental questions across the full spectrum of the Earth's (and Planetary) processes. This contribution builds on the existing literature of geomorphometry (the science of quantitative land-surface analysis) and feature extraction (translate land surface parameters into extents of geomorphological elements). It provides evidence of critical themes as well as emerging fields of future research in the digital realm, supporting the likely effectiveness of geomorphometry and feature extractions as they are advancing the theoretical, empirical and applied dimension of geomorphology. The review further discusses the role of geomorphometric legacies, and scientific reproducibility, and how they can be implemented, in the hope that this will facilitate action towards improving the transparency, and efficiency of scientific research, and accelerate discoveries in geomorphology. In the current landscape, substantial changes in landforms, ecosystems, land use, hydrological routing, and direct anthropogenic modifications impact systems across the full spectrum of geomorphological processes. Although uncertainties in the precise nature and likelihood of changes exist, geomorphometry and feature extraction can aid exploring process regimes and landscape responses. Taken together, they can revolutionise geomorphology by opening the doors to improved investigations crossing space and time scales, blurring the boundaries between traditional approaches and computer modelling, and facilitating cross-disciplinary research. Ultimately, the exploitation of the available wealth of digital information can help to translate our understanding of geomorphic processes, which is often based on observations of past or current conditions, into the rapidly changing future.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 25 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): F. Sedano, C. Navarro-Barranco, J.M. Guerra-García, F. Espinosa〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ocean sprawl is leading to the introduction of multiple artificial structures into the marine environment. However, the biota on these novel habitats differ from that on natural hard substrates. Amphipods, despite their ecological importance, are usually overlooked when comparing benthic assemblages on artificial and natural hard substrates. So as to assess the effects of artificial structures on amphipod assemblage and to identify the main factors involved, the amphipod assemblage structure was studied in five different substrates (seawalls, cubes, acropods, rip-raps and natural rock). Abiotic measurements of each substrate (complexity, rock composition, and age) were related to the ecological patterns. Complexity measurements seemed to affect the amphipod community structure, highlighting the need to consider physical complexity in eco-engineering actions. Amphipod assemblages were also affected by the secondary substrate (sessile biota), suggesting that artificial structures are indirectly shaping amphipod assemblages by firstly shaping the sessile biota. Future research should study the same secondary substrates across different artificial structures to separate the direct effects (caused by the artificial structures) from the indirect effects (caused by the sessile biota).〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0272771419310790-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 26 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): Shiwei Zhou, Jingjing Wu, Xiaoli Bi〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Woody plant encroachment into grasslands is a worldwide phenomenon. Still, there is a research gap in quantifying the ecological processes of coastal wetland ecosystems. Here, we combined soil stable isotope technology with geostatistical methods to quantify the spatial characteristics of soil δ〈sup〉13〈/sup〉C and δ〈sup〉15〈/sup〉N in a coastal wetland experiencing native shrub 〈em〉Tamarix chinensis〈/em〉 encroachment in the Yellow River Delta (YRD), China, and to clarify the possible mechanisms by which shrub-induced successional processes determined the spatial distribution of soil δ〈sup〉13〈/sup〉C and δ〈sup〉15〈/sup〉N. The results showed that soil δ〈sup〉13〈/sup〉C and δ〈sup〉15〈/sup〉N significantly decreased from bare land to grass and to shrub at the vegetation type level. Pearson correlation showed that soil δ〈sup〉13〈/sup〉C and δ〈sup〉15〈/sup〉N were positively related to soil salinity, but negatively related to plant variables (grass cover, shrub crown width and above-ground biomass). Scaling method indicated that soil δ〈sup〉13〈/sup〉C variation occurred at two different scales, 40 m and 150 m, representing influences of shrub 〈em〉T. chinensis〈/em〉 and environmental heterogeneity, respectively. Soil δ〈sup〉15〈/sup〉N variation was observed to occur at the 75 m scale, suggesting the combination effect of 〈em〉T. chinensis〈/em〉 and 〈em〉Suaeda glauca〈/em〉-dominated grass species. Furthermore, other soil and plant variables also exhibited two-scale characteristics similar to soil δ〈sup〉13〈/sup〉C. Therefore, the vegetation succession processes of coastal wetlands experiencing shrub encroachment could be understood well by combining soil stable isotope with GIS spatial tools. The spatial characteristics of soil stable isotopes help us establish strategies for protecting and managing coastal wetlands.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 25 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): Almir Nunes, Magnus Larson, Carlos Ruberto Fragoso〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉In the present study, a morphological model based on the main governing processes of inlet channels was developed for application in long-term simulations, requiring minimum data on forcing and only key information on the inlet geometry. The model considers the balance between the inlet sand transport due to tides and river flows and the longshore transport due to breaking waves. The resulting equations were numerically implemented and validated first through schematic simulations and then through an application to a real inlet. For the schematic simulations, the sediment transport rates in the inlet and alongshore were maintained constant and the behavior during evolution towards equilibrium was investigated and qualitatively assessed. Then, the model was applied to Mundaú Lagoon inlet (Brazil), a natural inlet sheltered by reefs and with a marked seasonality in river runoff. Thus, the model performance was validated for a complex setting over time scales of decades through comparisons with the observed inlet evolution determined from satellite images. The calculated results of inlet channel morphological evolution exhibited satisfactory agreement with observations. The computational efforts were low making the model suitable for long-term simulations where many alternative scenarios may be explored in a probabilistic manner. In conclusion, the developed model yielded robust and reliable simulation results having the potential for use in the assessment of long-term inlet channel evolution.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology, Volume 354〈/p〉 〈p〉Author(s): Yin-Hsuen Chen, Joann Mossa, Kunwar K. Singh〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The natural flood pulse maintains river-floodplain ecosystems through the exchange of freshwater resources between the main-stem and floodplain habitats. Few prior studies have quantified the relationship between flows and floodplain response including estimating inundation area, floodwater volumes, and slough connectivity. Floodplain modeling typically uses the flow-stage height relationship at river gauge stations. In this study, we compared a relative elevation model (REM) and the Hydrologic Engineering Center River Analysis System (HEC-RAS 1D) model using events from 2015 and 2016 covering a range of flows from the 1st to the 99th percentile for the Apalachicola River, Florida. Because digital elevation models (DEM) from LiDAR (light detection and ranging) data lack details of riverbed topography, we compared a LiDAR-alone and LiDAR-sonar combined DEM to assess their differences. Estimates from the REM and HEC-RAS models were compared to maps based on Landsat imagery-derived water and vegetation indices. In this river, we found a non-linear relationship between the inundated area and flow, increasing markedly through the 90th flow percentile after which increases are minimal. Inundated areas from both REM and HEC-RAS models were similar for all selected flow levels except at the 74th percentile (708 m〈sup〉3〈/sup〉/s) flow at which the REM produced 11% higher inundated area than HEC-RAS. Near the median flows, major sloughs were fully connected with backswamps and low-lying patches being inundated. At the higher flows, only a few anthropogenic features were exposed. Floodplain inundation estimates from Landsat performed poorly, detecting 9% with the modified normalized difference water index (mNDWI) and 41% with the open water likelihood index (OWL). These estimates were much lower than the HEC-RAS model (96% flooded), largely because the satellite is unable to penetrate dense forests and examine the floodplain surface, and the Landsat pixel size is twice the width of floodplain sloughs. The LiDAR-sonar combined DEM produced a higher floodwater volume estimate with the HEC-RAS model than using LiDAR-alone. The difference of 1,368,000 m〈sup〉3〈/sup〉 at the 1st percentile (142 m〈sup〉3〈/sup〉/s) and 2,825,000 m〈sup〉3〈/sup〉 at the 89th percentile (1133 m〈sup〉3〈/sup〉/s) demonstrate the limitation of using a LiDAR-alone DEM, which cannot penetrate the water surface, and the importance of surveying floodplains using sonar. Modeling results under predict historical wetting of the floodplain because Corps dredging made the main channel approximately 13% wider from its historical width in 1941. Further, in the past few decades, droughts and low flows have become more common because of varied upstream water uses, resulting in less inundation than in the past. Frequent high flows are required to maintain river-floodplain connectivity, floodplain forests, and other hydroecological functions in the Apalachicola River floodplain. Our findings present a basis to assess the legacy of past and ongoing disturbances, inform potential policy decisions for water and floodplain management, and provide a baseline for further research.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 25 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): Hiroto Higa, Shogo Sugahara, Salem Ibrahim Salem, Yoshiyuki Nakamura, Takayuki Suzuki〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Blue tide, which occurs in eutrophic semi-enclosed bays, is recognized as an important environmental problem because it causes mass mortality of fish and shellfish. In Tokyo Bay, which is a typical eutrophic semi-enclosed bay in Japan, fishery damage due to blue tide is frequently reported. Continuous monitoring is needed for effective water environment management and conservation because blue tides can be too short in duration to observe in the course of field observations. The aim of this study is to develop a model for estimating the distribution of blue tide based on sulfur concentration, which is a key element associated with blue tide. Using real-time data from the Geostationary Ocean Color Imager (GOCI) to estimate sulfur concentrations, we can clearly identify the spatial distributions of blue tides. We developed an empirical model using 〈em〉in situ〈/em〉 measurement of sulfur and remote sensing reflectance to obtain sulfur concentration (R〈sup〉2〈/sup〉 = 0.851). The developed model was applied to GOCI images acquired shortly after field observations during a blue tide on 24 August 2015 in Tokyo Bay in order to validate the accuracy of the sulfur estimation. Estimated and measured sulfur concentration showed less difference when the time between the start of field observations and GOCI image capture was comparatively small (R〈sup〉2〈/sup〉 = 0.704). Further, the blue tide distributions could be estimated by applying the developed model to other images acquired during blue tide occurrences at other dates and years. In conclusion, spatial distributions of blue tide in Tokyo Bay can be adequately estimated based on sulfur concentration determined from GOCI images.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 25 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): Rafaela B. Salum, Pedro Walfir M. Souza-Filho, Marc Simard, Carlos Alberto Silva, Marcus E.B. Fernandes, Michele F. Cougo, Wilson do Nascimento, Kerrylee Rogers〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Tree height is a key parameter to accurately quantify above ground biomass (AGB) of trees. Approaches that integrate airborne light detection and ranging (LiDAR) with mapped extents of forests may improve estimation of mangrove heights by providing considerably more measurements of mangrove tree heights than can be achieved using field based measurements alone. In this study, we present a validated method for quantifying mangrove AGB that was demonstrated for a mangrove forest at Guarás Island, Brazil. The application of LiDAR to estimate mangrove height was confirmed by correlating 89 tree heights measured in the field with LiDAR-derived mangrove heights, resulting in highly robust relationships for 〈em〉A. germinans〈/em〉, 〈em〉L. racemosa〈/em〉 and 〈em〉R. mangle〈/em〉 (R〈sup〉2〈/sup〉 = 0.90–0.97, RMSE of 1.24–0.67 m and RMSE% of 11.26%–25.97%). These relationships were used to calibrate a LiDAR-derived canopy height model (CHM) and develop robust relationships between the calibrated-CHM and field-based estimates of AGB (R〈sup〉2〈/sup〉 = 0.85–0.92, RMSE of 3.1 kg–42.53 kg, RMSE% of 20.66%–43.81%). This relationship was then applied to the CHM whilst accounting for tree density to estimate mangrove AGB. Total mangrove AGB per hectare was estimated to be 246.26 t ha〈sup〉−1〈/sup〉, corresponding closely with previous mangrove AGB measurements within the region. This study found that mangrove height and AGB are statistically related and these relationships can be applied to allometric equations for specific species to improve mangrove AGB estimates. This study demonstrates the capacity for LiDAR-derived tree heights to replace traditional approaches to estimating AGB and improving estimates of mangrove blue carbon storage. Application of LiDAR to determine tree heights will be particularly useful where mangrove is extensive and/or remote.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0272771419306134-fx1.jpg" width="487" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 26 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): Liqiang Zhao, Kotaro Shirai, Kentaro Tanaka, Stefania Milano, Tomihiko Higuchi, Naoko Murakami-Sugihara, Eric O. Walliser, Feng Yang, Yuewen Deng, Bernd R. Schöne〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Ocean acidification can negatively impact marine bivalves, especially their shell mineralization processes. Consequently, whether marine bivalves can rapidly acclimate and eventually adapt in an acidifying ocean is now increasingly receiving considerable attention. Projecting the fate of this vulnerable taxonomic group is also pivotal for the science of sclerochronology – the study which seeks to deduce records of past environmental changes and organismal life-history traits from various geochemical properties of periodically layered hard tissues (bivalve shells, corals, fish otoliths, etc.). In this review, we provide a concise overview of the long-term and transgenerational responses of marine bivalves to elevated 〈em〉p〈/em〉CO〈sub〉2〈/sub〉 manifested at different levels of biological organization, with a specific focus on responses of geochemical properties (stable carbon and oxygen isotopes, minor and trace elements and microstructures) of their shells. Without exception, positive transgenerational responses to an elevated 〈em〉p〈/em〉CO〈sub〉2〈/sub〉 scenario projected for the year 2100 have been found in all five bivalve species hitherto studied, under the umbrella of two non-genetic mechanisms (increased maternal provisioning and epigenetic inheritance), suggesting that marine bivalves have remarkable transgenerational phenotypic plasticity which allows them to respond plastically and acclimate rapidly in an acidifying ocean. Rapid transgenerational acclimation, especially in terms of physiological processes, however, hinders a reliable interpretation of proxy records. Transgenerationally acclimated bivalves can actively modify the calcification physiology in response to elevated 〈em〉p〈/em〉CO〈sub〉2〈/sub〉, which in turn affects the processes of almost all geochemical proxies preserved in their shells. In particular, stable carbon isotopes, metabolically regulated elements (Na, K, Cu, Zn, Fe, etc.), and shell microstructures can be highly biased. In this context, we propose a number of challenges and opportunities the field of sclerochronology may face.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 23 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): Ben Liu, Yuxin He, Yanzhen Zhang, Yongge Sun, Yuntao Wang, Ding He〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Organic matter (OM) cycling between coastal wetlands and their connected rivers is poorly constrained due to difficulties in assessing the composition of different OM sources (natural vs. anthropogenic). Bulk characteristics and lipid biomarkers were analyzed to distinguish different sources of OM in the sediments and soils of Liao River Delta, Northeast China, including Liao River Wetland, its connected Liao River, and nearby Daliao River. A similar range of stable carbon isotopic values (δ〈sup〉13〈/sup〉C〈sub〉org〈/sub〉) was observed in wetland soils (−27.8‰ to −22.6‰) and river sediments (−26.0‰ to −23.3‰). In contrast, significantly higher stable nitrogen isotopic values (δ〈sup〉15〈/sup〉N) were observed in Daliao River sediments (5.8‰–7.7‰) than both Liao River and wetland soils. Lipid biomarkers, especially 〈em〉n〈/em〉-alkyl lipids, phytosterols, triterpenoids, isoprenoids, monoalkyl glycerol ethers, and monoacylglycerols, indicated that the natural OM input in Liao River Delta was mainly of terrestrial origin, followed by 〈em〉in situ〈/em〉 aquatic and microbial inputs. In addition to natural OM, anthropogenic influences in the form of sewage and petroleum inputs were evidenced by the detection of fecal sterols, plasticizers, and petrogenic biomarkers. Biomarker distributions in samples from Liao River and Liao River Wetland suggested similar OM sources or close interaction between them, which may be caused by lateral transport considering the low elevation delta exposed to strong tidal effects. In contrast, significantly higher anthropogenic inputs were detected in Daliao River, with no connectivity to the Liao River wetland. Taking advantage of isotopic and biomarker data, the principal component analysis further suggests that both the natural wetland distribution and anthropogenic activities may affect the OM sources and distribution in coastal rivers, which serve as an important transit of OM to coastal oceans.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0272771419306183-fx1.jpg" width="367" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 23 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): Larissa Dsikowitzky, Trà My Iveta Nguyen, Leonard Konzer, Hongwei Zhao, Dao Ru Wang, Fei Yang, Jan Schwarzbauer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Tropical coastal ecosystems are particularly at threat from land-sourced pollution, resulting from the input of harmful substances from a multitude of emission sources. Although not intensively studied to date, this concerns also the contamination of coral reefs with pesticide classes apart from the frequently reported organochlorine pesticides. We therefore investigated the occurrence and spatial distribution of these compounds in water samples from the northeast coast of Hainan, a tropical Chinese island. The study area included two sensitive coastal habitats: a shallow bay and fringing coral reefs with seagrass beds.〈/p〉 〈p〉The results revealed the occurrence of photosystem(II) triazine herbicides at most sampling stations in the coastal waters, especially of prometryn (maximum concentration 440 ng L〈sup〉−1〈/sup〉). A chemical characterization of aquaculture pond waters gave evidence that aquaculture was the source of this contamination. Prometryn was detected in many sampled ponds and could thus be useful as source-specific molecular indicator to trace aquaculture emissions in coastal areas. Concentrations of triazine herbicides in the study area (〈10–440 ng L〈sup〉−1〈/sup〉) were lower than reported acute effect concentrations for dinoflagellates, seagrass and algae. Thus, no acute toxic effects on local coral reefs and seagrass beds are expected. Chronic exposures of sensitive species to low concentrations of the detected triazine herbicides have to date not been studied. Therefore, we cannot exclude deteriorating effects in the long-term, especially in combination with other stressors such as rising sea surface temperature, which can enhance the sensitivity to pollutants. Future studies in other world regions should consider prometryn and further triazine herbicides as harmful pollutants from aquaculture emissions.〈/p〉 〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0272771419303671-fx1.jpg" width="277" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science, Volume 235〈/p〉 〈p〉Author(s): Candela Marco-Méndez, Luis Miguel Ferrero-Vicente, Kenneth L. Heck〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉While it has been well established that waterbirds can consume substantial amounts of submerged aquatic vegetation (SAV) on their wintering grounds, relatively little is known about their effects on SAV in the northern Gulf of Mexico (nGOM). We measured the impact of wintering American coot (〈em〉Fulica Americana〈/em〉) foraging on native wild celery (〈em〉Vallisneria americana〈/em〉) and exotic Eurasian water milfoil (〈em〉Myriophyllum spicatum〈/em〉) using caging experiments at two locations in upper Mobile Bay during winter 2013–2014. We also determined feeding preferences using tethering experiments, and monitored the location of coots and the feeding behavior of individual birds. Coots were significantly more abundant over Eurasian watermilfoil than native wild celery. Caging experiments usually showed higher SAV biomasses in exclusion cages, and suggested a larger impact of coot foraging on milfoil than wild celery. Video recordings confirmed that coots were responsible for the SAV losses detected with both caging and tethering experiments, and dietary analyses supported experimental results and highlighted the role of milfoil in the coot's diet (86.9 ± 8.9% of stomach contents). Tethering results showed a preference for wild celery over milfoil, which is likely explained by the higher nutritional quality of wild celery (19.26 ± 1.21 C:N ratio) compared to Eurasian milfoil (25.01 ± 2.45 C:N ratio). Overall, our results are similar to those of several prior seagrass herbivory studies in showing that herbivores do not always feed on their preferred food, presumably because other factors, such as proximity of refuges from predators or competition for food resources, are of overriding importance.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science, Volume 235〈/p〉 〈p〉Author(s): Yue-hua Huang, Larissa Dsikowitzky, Fei Yang, Jan Schwarzbauer〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Wastewater treatment plants in large urban agglomerations are worldwide among the main sources of emerging contaminants in aquatic systems. The present study is a first comprehensive characterization of potentially harmful emerging contaminants in sewage of a Chinese urban area. The study area Haikou City is located at the coast of tropical Hainan Island. A GC/MS based non-target screening approach for the identification of a wider range of lipophilic to semi-polar organic sewage constituents was applied. Pollution originating from sewage was tracked in the urban coastal waters by using selected source-specific indicators.〈/p〉 〈p〉A set of sewage constituents with a high structural diversity was identified comprising both, industrial and household chemicals. Ingredients of personal care products, pesticides and pharmaceuticals were found, that were rarely reported from other regions of the world. This observation might be attributed to different environmental legislation and consumption habits in China. Exceptionally high concentrations of the illegal drug ketamine with up to 1100 ng L〈sup〉−1〈/sup〉 were detected, suggesting its high popularity and consumption rate. Noteworthy, sewage constituents reported here for the first time were the pharmaceuticals marmesin, oxolamine and ansimar also with high concentrations of up to 1200 ng L〈sup〉−1〈/sup〉.〈/p〉 〈p〉Elevated concentrations of sewage indicators in the main city area suggest the overflow of the sewage system, in particular in the period of a typhoon event. Tracing the sewage contamination in the surface water system of the coastal urban area of Haikou revealed a lower level of pollution. The concentration ranges point to no acute risks for the coastal ecosystem due to sewage inputs from the city area.〈/p〉 〈p〉Generally, the detected spectrum of municipal emerging contaminants has to be considered for the testing and technical improvement of wastewater treatment techniques, for regular monitoring of the surface water quality and for environmental impact assessment in China. Furthermore, the compound spectrum reported here is a good reference point for the composition of municipal sewage in other emerging economies.〈/p〉 〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0272771419305372-fx1.jpg" width="500" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 22 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): Si Son Tong, Jean Paul Deroin, Thi Lan Pham〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Tidal flats on the north coast of Vietnam suffer diurnal tide with a tide range varying between 0.3 m and 3.5 m. Along the 350 km long coastline, the diversity of environmental conditions induces various tidal flats with different characteristics. This study applies the waterline method for multi-temporal satellite images to build Digital Elevation Models (DEMs) of tidal flats during the last 25 years. 117 Landsat images acquired with TM, ETM+, and OLI have been processed to construct tidal flat DEMs in 1989, 2000, and 2014. Waterlines extracted from single spectral bands (near-infrared [NIR], short wave infrared [SWIR]) or band ratios (normalized difference water index [NDWI], normalized difference vegetation index [NDVI], Green/SWIR) of the Landsat data have been compared with waterlines digitalized on Spot, Aster and Worldview 2 images. This experiment allows us to determine the best band (or band ratio) for extracting waterlines depending on local conditions. Consequently, the study shows that the Green/SWIR ratio image is a good solution for extracting waterlines in the black coal tidal flats of Cam Pha. However, the NDWI index appears to be a better choice for the other parts of the study area. The vertical accuracy of the tidal flat DEMs reaches 0.144 m. The change analysis of the DEMs also emphasizes the tidal flat evolution in both vertical and horizontal dimensions, i.e. erosion or accretion. The erosion of the tidal flats along the northern coast of Vietnam is particularly developed in the area extending from Yen Hung to Mong Cai, especially in Mong Cai with an amount of about 50 × 10〈sup〉6〈/sup〉 m〈sup〉3〈/sup〉 of sediments lost between 1989 and 2014. On the contrary, the tidal flats in the south of the study area show a high rate of deposition due to the sediments fed by Red and Thai Binh rivers. About 35 × 10〈sup〉6〈/sup〉 m〈sup〉3〈/sup〉 of sediments deposited in the tidal flat surrounding the Red River mouth between 1989 and 2014. This study represents a development of the waterline extraction method to investigate the evolution of tidal flat at a large scale and a diversified coastal environment using optical satellite images and fieldwork.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science, Volume 235〈/p〉 〈p〉Author(s): Emily Russ, Cindy Palinkas〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Like many estuaries, the upper Chesapeake Bay effectively traps sediment from its tributaries and shorelines. However, evolving sediment dynamics from human influences such as increased soil conservation, dam construction (and subsequent infill), and increased shoreline stabilization have altered sediment loads to the Bay. Sediment budgets are important tools for evaluating sediment dynamics through identifying sources, sinks, and transport pathways. The most recent upper Bay sediment budget was developed 〉25 years ago and does not reflect the evolution of sediment delivery. The objective of this study is to develop an updated sediment budget through quantitative analysis of the upper Bay's major sediment sources (Susquehanna River and shoreline erosion) and sinks (deposition in the Susquehanna Flats region and mainstem Bay). Results indicate that Susquehanna River input to upper Bay has decreased during low flows, due to implementation of conservation-management strategies, but increased during high flows, from infilling of the Conowingo Reservoir. Inputs from shoreline erosion have decreased due to increased shoreline stabilization. Mass accumulation rates in the upper Bay generally decrease with distance downstream, but elevated sedimentation rates occur in deeper water, and possibly represent sediment focusing near channels. Insights gained from this study not only inform sediment management strategies in the Bay and similar systems, but also can help forecast potential future trajectories from environmental and anthropogenic drivers. For example, changing climate is projected to increase precipitation, storminess, and sea-level rise (SLR), which would increase both Susquehanna River and shoreline erosion sediment inputs. These changes could help the sedimentation rates keep pace with SLR but also may degrade downstream ecosystems due to increased fine-sediment input and turbidity. Shoreline stabilization will also likely increase, which would reduce shoreline erosion and thus sand inputs necessary for some nearshore benthic habitats to keep pace SLR.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology, Volume 354〈/p〉 〈p〉Author(s): Sijin Li, Liyang Xiong, Guoan Tang, Josef Strobl〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Landform classification is one of the most important aspects in geomorphological research, dividing the Earth's surface into diverse geomorphological types. Thus, an accurate classification of landforms is a key procedure in describing the topographic characteristics of a given area and understanding their inner geomorphological formation processes. However, landform types are not always independent of one another due to the complexity and dynamics of interior and external forces. Furthermore, transitional landforms with gradually changing surface morphologies are widely distributed on the Earth's surface. With this situation, classifying these complex and transitional landforms with traditional landform classification methods is hard. In this study, a deep learning (DL) algorithm was introduced, aiming at automatically classifying complex and transitional landforms. This algorithm was trained to learn and extract landform features from integrated data sources. These integrated data sources contain different combinations of imagery, digital elevation models (DEMs), and terrain derivatives. The Loess Plateau in China, which contains complex and transitional loess landforms, was selected as the study area for data training. In addition, two sample areas in the Loess Plateau with complex and transitional loess hill and ridge landforms were used to validate the classified landform types by using the proposed DL method. Meanwhile, a comparative analysis between the proposed DL and random forest (RF) methods was also conducted to investigate their capabilities in landform classification. The proposed DL approach can achieve the highest landform classification accuracy of 87% in the transitional area with data combination of DEMs and images. In addition, the proposed DL method can achieve a higher accuracy of landform classification with better defined landform boundaries compared to the RF method. The classified loess landforms indicate the different landform development stages in this area. Finally, the proposed DL method can be extended to other landform areas for classifying their complex and transitional landforms.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology, Volume 354〈/p〉 〈p〉Author(s): Sergio R. Dillenburg, Patrick A. Hesp, Robert Keane, Graziela Miot da Silva, André O. Sawakuchi, Ian Moffat, Eduardo G. Barboza, Volney J.B. Bitencourt〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉This study examines the southeastern end of the Younghusband Peninsula in South Australia at a location called The Granites in order to gain a better understanding of the processes of formation of the foredune ridge system, and to investigate the drivers that controlled its progradational development during the Holocene. Our findings are based on a morphological analysis, a ground penetrating radar survey, and 〈sup〉14〈/sup〉C and OSL dating. The Younghusband Peninsula at The Granites was formed by an initial aggradational phase resulting in a single complex foredune ridge, and which ended around 4.3 ka, and by a regressive (progradational) barrier phase (750 m wide) that developed in the last 4.3 ka, under very low rates of progradation (0.38 to 0.09 m/yr). The last part of this phase shows significant foredune ridge building in the last 1000 years or so. Barrier progradation via foredune ridge development is likely an effect driven by low wave energy that favored conditions for coastal stability and foredune formation. Paleontological and GPR data indicate a maximum sea-level of +1.23 to +1.5 m, respectively, during initial barrier development. The foredune ridge plain of the barrier experienced at least three phases of significant aeolian activity with ages centered at around 3.9, 3.4 and 3.0 ka suggesting their occurrence at 500 to 400-year events. Computer modelling indicates that sediments for the progradational phase of the barrier were provided by the forced regression produced by a sea-level fall over the past 4.3 ka. The large foredune complex formed during the last phase of progradation could be the result of both the very low progradation rate of 0.09 m/yr, and periods of disturbance possibly related to enhanced storm activity.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology, Volume 354〈/p〉 〈p〉Author(s): Yu Zhang, Marwan A. Hassan, Leonora King, Xudong Fu, Erkan Istanbulluoglu, Guangqian Wang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The Loess Plateau in China is the largest and deepest loess deposit in the world. The surficial geology is dominated by Quaternary loess deposits of varying thicknesses, which exhibit some of the fastest erosion rates in the world. Although the plateau has been traditionally thought of as morphologically homogenous, river network morphometrics in this area are spatially variable, suggesting that landscape evolution processes across the plateau are sensitive to variability in local conditions. We divided the plateau into sub-basins and examined six DEM-derived morphometric parameters: Aspect Ratio, Anisotropic Coefficient Variation (ACV), Bifurcation Ratio, Concavity, Steepness, and Mean Junction Angle. The sub-basins exhibited low aspect ratios, high bifurcation ratios and large junction angles relative to landscapes around the world, however they varied intra-regionally relative to each other. Through the use of Principal Component Analysis and Cluster Analysis, we observed specific spatial variation in morphometrics attributable to differences in climate, lithology and tectonics along a NW-SE transect through the plateau. Sub-basins in the elevated plateau regions are more oval with higher aspect ratios and lower ACV values while those located in down-dropped valley regions have smaller junction angles, lower concavity and steepness index. Sub-basins in the transition area between down-dropped and elevated parts of the plateau are distinguished by their high bifurcation ratios and elongated shape. We propose a conceptual model to explain the relationship between these morphometrics and the local environmental conditions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 13 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology〈/p〉 〈p〉Author(s): Piotr Cienciala, Andrew D. Nelson, Andrew D. Haas, Zewei Xu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The rates at which sediment from the landscape is recruited to channel networks reflect lateral geomorphic connectivity and have significant implications for biophysical river systems. By strongly influencing sediment supply regime, such inputs control the dynamics and characteristics of the channel as well as the associated habitat and biota. The main objective of this research was to disentangle the relative importance of geomorphic and biological factors which define spatial patterns in lateral connectivity by promoting or restricting bank erosion, avulsions, and slope failures. Focusing on a forested, formerly glaciated mountain basin in the interior Pacific Northwest, we combined extensive field surveys with remote sensing data (LiDAR, aerial imagery) to obtain metrics representing this complex suite of landscape characteristics. The interpretation of evidence yielded by correlations between these variables, a regime model, and qualitative observations, suggest that, at a multi-decadal timescale between major landscape disturbances, lateral connectivity patterns in Sullivan Creek may be, to a large extent, governed by a combination of biotic factors and glacial legacies. In particular, forest canopy metrics were key predictors of hillslope stability as well as bank and valley floor resistance, suggesting a pivotal influence of root reinforcement. On the other hand, instream large wood abundance was closely related to channel splitting, which reflects its role in promoting channel avulsions. More extensive bank erosion in reaches dominated by drift deposits appeared to indicate glacial legacies. Furthermore, a strong association between bank erosion and colluvial inputs suggested a close coupling within the channel-hillslope system. Lateral confinement – defined as the proportion of the channel length abutting against bedrock, terraces, fans and roads – was negatively associated with channel braiding; the relationships linking confinement with bank erosion and the magnitude of colluvial inputs (negative and positive association, respectively) were relatively weak. Taken together, findings emerging from this research suggest that better understanding of lateral geomorphic connectivity patterns in mountain river basins similar to our study site requires that both channel processes and broader, biophysical landscape system be considered.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169555X20300064-ga1.jpg" width="245" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology, Volume 354〈/p〉 〈p〉Author(s): A. Tena, H. Piégay, G. Seignemartin, A. Barra, J.F. Berger, B. Mourier, T. Winiarski〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉One of the main drivers of overbank fine deposition and floodplain formation is the hydrological connectivity between the channel and the floodplain. Channel correction (i.e., groyne field construction within the main flow channel and secondary channel disconnections) and flow regulation can typically lead to a disconnection of riverine floodplains and disturbances that directly affect terrestrialisation. Channel correction and flow regulation can sometimes occur successively, and it is challenging to distinguish the roles of each. This work attempts to assess the respective effects of two phases of channel regulation (correction versus flow regulation) on floodplain terrestrialisation by comparing three bypassed reaches of the Rhône, France (Pierre-Bénite, Péage-de-Roussillon and Donzère-Mondragon). We applied a transversal methodology coupled with GIS analysis (old maps, Orthophotos, DEM's, etc.) to understand processes of channel-planform evolution, conducted a sediment survey (metal rod) to assess floodplain terrestrialisation, and performed sediment sampling (manual auger) to obtain surface sediment metal content levels (X-ray Fluorescence and Inductively Coupled Plasma Mass Spectrometry). We found a general trend of channel narrowing within the three reaches, among which approximately 40% was found to be associated with correction works while 20% was attributed to flow lowering caused by channel bypassing. The number of flowing channels in all sections declined significantly, and local anabranching reaches evolved into very stable single thread channels. Overbank sedimentation declined significantly over the period, with very high sedimentation levels observed immediately after correction works and with very low sedimentation levels observed after diversion. We also found overbank flooding (in the number of days per year) decreased while fine sediment thickness increased. Similarly, the highest concentrations of metals (Zc, Pb, and Cu) were found to be associated with a low connection frequency and vice versa. When similar 2-staged terrestrialisation patterns are observed in all three reaches, they differ in chronology and driving factors because of their longitudinal positioning and specific local conditions.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science, Volume 235〈/p〉 〈p〉Author(s): K.D. Huguenard, D.J. Bogucki, D.G. Ortiz-Suslow, J.H. MacMahan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The nearshore response to synoptic meteorological patterns called Cold Air Outbreaks (CAOs) was studied with a cross-shelf mooring array located 7 km west of an estuarine outflow in the Northern Gulf of Mexico. The array consisted of 6 stations that spanned the nearshore measuring waves, currents, temperature, and salinity for a two-week period in December 2013. CAOs are prevalent during winter and are characterized by the passage of atmospheric cold fronts with offshore winds known to cool coastal waters. The prefrontal phases of CAOs coincided with downwelling favorable winds and westward flow that introduced a river plume into the nearshore. Offshore winds during the high pressure phase formed a two-layer circulation with offshore flow in the surface layer and onshore flow beneath, which was moderated by a river plume. The downwind advection of the river plume tended to enhance surface transport until the plume was flushed out of the nearshore, which formed adverse density gradients that reduced surface transport through vertical mixing. When the plume was not fully flushed out of the inner shelf, surface transport remained enhanced during the high pressure phase due to stratification that limited the formation of adverse density gradients. When the plume was initially shore detached at the onset of the high pressure phase, offshore flow was not enhanced by the downwind advection of the plume due to the existence of initial adverse density gradients. These results highlight the effects of nearshore river plumes in regulating inner shelf circulation during cold fronts.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology, Volume 354〈/p〉 〈p〉Author(s): Asunción Romero-Díaz, José Damian Ruíz-Sinoga, Francisco Belmonte-Serrato〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Badlands are present throughout the world, but not everywhere do they have the same morphology. The main objective of this study is to try to understand why these different morphologies occur by analysing the physical-chemical and mineralogical characteristics of the parental material in which badlands have developed. The study was carried out in three areas of the Region of Murcia (south-east Spain): Abanilla, Mula and Gebas.〈/p〉 〈p〉Several analyses were carried out: (i) field analysis (orientation, slope, length and shape of the slope, presence and characteristics of the rills, vegetation, vegetation pedestals, exposed roots, stoniness, physical and biological crusts, saline efflorescence, cracks, popcorn, piping processes, sedimentation areas and mass movements); (ii) physical-chemical analysis of the soils (colour, texture, aggregate stability, bulk density, organic matter, pH, electrical conductivity, cations and cation exchange capacity, total or equivalent calcium carbonate, sodium absorption ratio and exchangeable sodium percentage); and (iii) mineralogical analysis.〈/p〉 〈p〉The results of the analyses reveal how the rounded shapes in the badlands that appear in Abanilla have significant differences with respect to the angled shapes of Mula and Gebas, which could explain the different morphologies. In general, Abanilla has very small amount of sand, higher bulk density, small amount of organic matter, lower cation exchange capacity, and very high salinity, as shown in the values of electrical conductivity, sodio, SAR and ESP.〈/p〉 〈p〉On the other hand, similarities were found between the badlands of the Region of Murcia with the 〈em〉calanchi〈/em〉 (angled shapes) and 〈em〉biancane〈/em〉 (rounded shapes) of Italy.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science, Volume 235〈/p〉 〈p〉Author(s): Lorenzo Melito, Matteo Postacchini, Alex Sheremet, Joseph Calantoni, Gianluca Zitti, Giovanna Darvini, Pierluigi Penna, Maurizio Brocchini〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The evolution of different wave components as they propagate within a microtidal inlet during a storm occurring from 24–26 January 2014 is analysed, in order to improve knowledge on how microtidal river mouths typical of the Adriatic Sea behave. For the first time, the “low-pass filter” mechanism previously ascertained at several macrotidal oceanic inlets around the world has been observed in the field with remarkably specific hydrodynamic conditions, i.e. low tide excursion, permanent connection with the sea and generally milder wave climate than in the ocean. Sea/swell (SS) waves were strongly dissipated before entering the river mouth, through the combined action of wave breaking due to reducing depths and opposing river currents enhanced by rainfall. Infragravity (IG) waves propagated upstream and significant IG wave heights of up to 0.4 m, about 13% of the local water depth, have been observed 400 m upriver (about 10 times the local SS peak wavelength) during storm climax. The IG wave energy here represented over 4% of the maximum offshore storm energy. IG wave components travelled upriver at estimated velocities between 3.6 m/s and 5.5 m/s (comparable with speeds of nonlinear long waves) during intense storm stages up to 600 m into the river channel (about 15 times the local SS peak wavelength), and are enhanced by tide-induced increase in water depths. It is estimated that tide-induced excursion accounted for about 80% of the total mean water elevation at storm peak at about 400 m into the river. Finally, tidal oscillations are detected up to 1.5 km upstream (about 40 times the local SS peak wavelength). This study highlights the dominance of astronomical tide over both wave setup and storm surge in controlling the upriver propagation of IG waves, even in a microtidal environment.〈/p〉〈/div〉

Description: 〈p〉Publication date: Available online 22 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology〈/p〉 〈p〉Author(s): J.A. Pollard, T. Spencer, S.M. Brooks, E.K. Christie, I. Möller〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉At the coast, risk arises where, and when, static human developments are situated within dynamic surroundings. Barrier islands are often sites of heightened coastal risk since they frequently support substantial human populations and undergo extensive morphological change owing to their low-lying form and persistence in energetic hydrodynamic and meteorological conditions. Using the mixed sand-gravel barrier of Blakeney Point, this study argues that to avoid an only partial understanding of coastal zone processes, it is necessary to make use of multiple shoreline proxies, capturing processes operating both at different timescales and different cross-shore positions. Here, five shoreline proxies were extracted from three data sources. Shoreline error was quantified and compared to observed shoreline change rates to establish proxy-specific, appropriate timescales for shoreline change analysis. The map derived Mean High Water Line at Blakeney Point revealed landward retreat of −0.61 m a〈sup〉−1〈/sup〉 over the past 130 years with a shift from drift- towards swash-alignment of the barrier since 1981. Over the past 24 years, the High Water Line, Ridge Line and Vegetation Line reveal proxy-specific response to management regime change. The termination of barrier reprofiling of the eastern section of the barrier has resulted in increased sediment release to the downdrift barrier terminus, buffering retreat there at the expense of the updrift section. The Vegetation Line represents an effective proxy for storm-driven overwash with maximum shoreline retreat during surge events of 172 m, illustrating a strong event-driven component to barrier morphodynamics. By comparison to the other proxies, the LiDAR (Light Detection and Ranging) derived Mean High Water Line offers relatively limited insights into barrier dynamics, emphasising the importance of multi-proxy approaches. In the face of technological advance, we demonstrate the continued importance of critical attention towards the dependencies that exist between shoreline proxy selection and the processes that can be observed as a result.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 22 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology〈/p〉 〈p〉Author(s): Hannah M. Joyce, Jeff Warburton, Richard J. Hardy〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The supply, transfer and deposition of sediment from channel headwaters to lowland sinks, is a fundamental process governing upland catchment geomorphology, and can begin to be understood by quantifying 2D river planform adjustments over time. This paper presents a catchment scale methodology to quantify historic patterns of 2D channel planform adjustment and considers geomorphic controls on 2D river stability. The methodology is applied to 18 rivers (total length = 24 km) in the upland headwaters of the previously glaciated Wasdale catchment (45 km〈sup〉2〈/sup〉), Lake District, northwest England. Planform adjustments were mapped from historic maps and air photographs over six contiguous time windows covering the last 150 yr. A total of 1048 adjustment and stable reaches were mapped. Over the full period of analysis (1860–2010) 32% (8 km) of the channels studied were adjusting. Contrasts were identified between the geomorphic characteristics (slope, catchment area, unit specific stream power, channel width and valley bottom width) of adjusting and stable reaches. The majority of adjustments mapped were observed in third and fourth order channels in the floodplain valley transfer zone, where the channels were laterally unconfined (mean valley bottom widths of 230 ± 180 m), with low sediment continuity. In contrast, lower order channels were typically confined (mean valley bottom widths of 31 ± 43 m) and showed relative 2D lateral stability. Hence, valley bottom width was found to be important in determining the available space for rivers to adjust. Over the full period of analysis 38% of planform adjustments involved combined processes, for example, as bar and bend adjustments. The study demonstrates the importance of stream network hierarchy in determining spatial patterns of historic planform adjustments at the catchment scale. The methodology developed provides a quantitative assessment of planform adjustment patterns and geomorphic controls, which is needed to support the prioritisation of future river management and restoration.〈/p〉〈/div〉 〈/div〉 〈div xml:lang="en"〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0169555X20300167-ga1.jpg" width="199" alt="Unlabelled Image" title="Unlabelled Image"〉〈/figure〉〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 20 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology〈/p〉 〈p〉Author(s): Nathalie Neagu, Ari Matmon, Yehouda Enzel, Naomi Porat, ASTER Team〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The long-term bedrock incision of streams in the northeastern Negev has been dictated, since the Early Pliocene, by the subsidence of the Dead Sea basin. However, this incision is accompanied by very long intervals of sediment aggradation. Here, we document the Quaternary-scale fluvial response to changing base-level, lithology, structure, and climate along the hyperarid Nahal Zafit, NE Negev. The oldest (~1–2 Ma) alluvial remnants point to a widespread beveled bedrock pediment at the base of the Hazera anticline. This pediment, like other stream-pediment-anticline relationships in the region, provides the baseline framework into which Nahal Zafit incises. During the Early to Middle Pleistocene, this pediment was the base-level for all streams emerging out of the anticlines. The tectonic subsidence of the regional base-level at the rift margin farther downstream, has caused incision and upstream migration of bedrock knickpoints, triggering the development of a wide incised valley in the Mazar syncline, adjacent to the Hazera anticline. Since ~330 ka, fluvial terraces, landslides and taluses record intervals of basin-wide fluvial deposition under prevailing hyperarid to arid climate. Despite the general arid climate, prolonged fluvial deposition intervals occurred at ca. 330–265, 230–125, and 110–20 ka. Rapid and quite short-duration bedrock incision occurred in-between these, much longer, intervals of aggradation. In addition to the proposed climatic imprint on fluvial aggradation-incision cycles and the first-order base-level control of the rift margin fault, the formation of strath terraces and distribution of stored sediments within the drainage basin point to the fundamental role that lithology and structure play in the Quaternary evolution of the NE Negev watersheds.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology, Volume 354〈/p〉 〈p〉Author(s): Ilenia M. D'Angeli, Larissa A. Naylor, Martin Lee, Ana Z. Miller, John Mylroie, Jo De Waele〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉San Salvador (Bahamas) is a carbonate island with dozens of flank margin caves formed in the phreatic zone by fresh seawater mixing within the freshwater lens. These caves have no direct connection with the sea, and form at or close to the tidally influenced fluctuating water table. After sea-level fall, in their subaerial parts caves are enlarged mainly by rock dissolution and by erosion close to the water level, condensation-corrosion and breakdown processes. For understanding the geomorphological features observed in these caves and how they are related to light attenuation, we investigated three sampling sites in the tidally influenced zone of Lighthouse Cave, which has been re-invaded by seawater during the Holocene sea-level highstand. A freshwater lens no longer exists within or adjacent to the cave. Rock samples were collected above and below the internal lake shores close to the entrance, and in the twilight and dark zones of this cave. Light and electron microscopy examinations were conducted for detecting microbial cells, as well as bioconstruction and bioweathering features. In addition, a high precision laser scanner was used for characterising sample microtopography. Our data showed that the microtopography and geomorphology of the lake shore samples (cave entrance) are dominated by bioweathering, whereas the samples of the twilight and dark zones are controlled by a combination of both bioweathering and bioconstructive processes depending on light availability. Bioconstructive structures, such as semi-planar lamination, at the fluctuating water level of the Lighthouse Cave show that dissolution due to water mixing of sea and freshwater in the Holocene is no longer the most important speleogenetic process. We propose that the geomorphological evolution is strongly influenced by the degree of rock diagenesis more than the initial mechanism of speleogenesis.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 17 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): Liju Wang, Lingling Xie, Quanan Zheng, Junyi Li, Mingming Li, Yijun Hou〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Using mooring-observed horizontal velocities and temperature from July 28 to August 2, 2005, this study analyzes the temporal-vertical variation of the diagnostic vertical velocity and mass transport during passage of tropical storm Washi (2005) over the northwestern continental shelf of the South China Sea (SCS). The results show that the total vertical velocity is of the order of 〈em〉O〈/em〉(1〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mo linebreak="goodbreak" linebreakstyle="after"〉×〈/mo〉〈/mrow〉〈/math〉10〈sup〉−4〈/sup〉) m s〈sup〉−1〈/sup〉 in the mixed layer above 25 m, and of 〈em〉O〈/em〉(1〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mo linebreak="goodbreak" linebreakstyle="after"〉×〈/mo〉〈/mrow〉〈/math〉10〈sup〉−5〈/sup〉) m s〈sup〉−1〈/sup〉 in the lower layer. Dynamically, the geostrophic advection and unsteady behavior of density induced by near-inertial oscillation are dominant factors in the upper and lower layers, respectively. As tropical storm Washi (2005) passed by from July 29 to 31, 2005, the upward vertical velocity was dominant and significantly enhanced to the order of 〈em〉O〈/em〉(1〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mo linebreak="goodbreak" linebreakstyle="after"〉×〈/mo〉〈/mrow〉〈/math〉10〈sup〉−3〈/sup〉) m s〈sup〉−1〈/sup〉. The diagnosed vertical velocity in the upper layer is one order greater than the averaged Ekman pumping velocity, which occurred one day earlier. The vertical advection transport calculated from the diagnosed vertical velocity reaches 〈em〉O〈/em〉(1〈math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"〉〈mrow〉〈mo linebreak="goodbreak" linebreakstyle="after"〉×〈/mo〉〈/mrow〉〈/math〉10〈sup〉−5〈/sup〉) kg s〈sup〉−1〈/sup〉m〈sup〉−3〈/sup〉, one order greater than that induced by turbulent mixing. Time-averaged transports by vertical advection and mixing are both upward in the layer above the thermocline during the storm passage.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 1 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology, Volume 354〈/p〉 〈p〉Author(s): Fei Yang, Gan-Lin Zhang, Daniela Sauer, Fan Yang, Ren-Min Yang, Feng Liu, Xiao-Dong Song, Yu-Guo Zhao, De-Cheng Li, Jin-Ling Yang〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The interactions between geomorphology, sediment distribution and soil development in alpine regions are poorly understood. In this study, we analyzed the spatial variations of different sediment types and corresponding soils in 15 pedosedimentary profiles across three major geomorphic units in an alpine ridge-valley basin of the Qilian Mountains, northeastern Qinghai-Tibetan Plateau. Particle size distribution was used to trace the sediment types. Inorganic and organic carbon concentrations were included as metrics of soil processes. Aeolian silts from both distant and proximal sources cover floodplains, hillslopes and some positions on alluvial fans, while the distribution of fluvial sediments and periglacial slope deposits are much more limited due to the coverage of loess. The soils vary in response to sediment types and climatic conditions under the influence of their geomorphic settings. The vertical distribution patterns of carbonates in soil profiles show considerable differences among different geomorphic units, reflecting their contrasting water balance and migration pathways. Soil organic carbon accumulates most extensively in aeolian silts with sufficient water supply. A special pedogenic soil horizon – the mattic epipedon is formed primarily in loessial sediments in 〈em〉Kobresia〈/em〉 ecosystems. The complex entanglement of fine earths and massive grassroots make the mattic epipedon extremely resilient, which helps to preserve the soils and to shape the landscapes. By integrating geomorphology, sedimentology, ecology and pedology, the outcomes of this study promote the understanding of the evolution of typical landscapes and ecosystems of the northeastern Qinghai-Tibetan Plateau and many other periglacial settings.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science, Volume 235〈/p〉 〈p〉Author(s): Celine E.J. van Bijsterveldt, Bregje K. van Wesenbeeck, Daphne van der Wal, Norma Afiati, Rudhi Pribadi, Benjamin Brown, Tjeerd J. Bouma〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉 〈p〉Globally, erosion of muddy tropical coasts that are dominated by aquaculture ponds, is an increasing problem. Restoration of mangrove greenbelts may counteract such erosion, by restoring the sediment balance. Hence, we aim to unravel the processes controlling natural mangrove regeneration in both “landward” (i.e., into aquaculture ponds) and seaward direction, using the fast eroding coastline of Demak (Indonesia) as case study. Firstly, we investigated which physical and chemical factors drive landward mangrove expansion by relating them to the presence/absence of mangrove seedlings in abandoned aquaculture ponds. Secondly, we investigated which physical parameters control seaward mangrove expansion by relating them to expansion and retreat at the sea-side of mature mangrove stands.〈/p〉 〈p〉Landward mangrove expansion into abandoned aquaculture ponds was positively related to both emergence time (%) and sediment stability (i.e., shear strength), which are in turn both associated to bed level elevation and pond drainage. Surprisingly, there was no effect of soil chemistry. Seaward expansion of existing mangrove stands was strongly associated to foreshore morphology. Mangroves only expanded in the presence of an elevated mudflat, whereas the absence of a mudflat in combination with a concave (hollow) profile was associated with mangrove retreat. Our findings suggest that restoration of a mangrove greenbelt can be stimulated landward by improving drainage of abandoned aquaculture ponds. This enhances sediment stability and allows ponds to accrete. Seaward expansion can be induced by restoring foreshore morphology. Present results are discussed in the context of large-scale applications.〈/p〉 〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science, Volume 235〈/p〉 〈p〉Author(s): Kai Wang, Yijun Hou, Shuiqing Li, Mei Du, Jinrui Chen, Jiuyou Lu〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The coastal regions of the East China Sea are frequently threatened by the increased sea level induced by intense tropical cyclones. In this study, a coupled wave-circulation model ADCIRC + SWAN is used to investigate the spatial and temporal characteristics of storm surges and wave setup heights in the southeastern coastal area of China during two severe weather events with different tracks: Typhoon Saomai, which made direct landfall, and the bypassing Typhoon Chan-hom. By definition, the storm surge is attributable to the wind forcing, while the wave setup results from the wave radiation stress. The simulated sea levels agree well with the observations, with improved results when the wave setup was considered. The simulation results showed clearly different spatial patterns depending on the track type. The maximum storm surge resulted from the cumulative effect of the local onshore wind forcing, occurring on the right side of the Typhoon Saomai track and the left side of the Typhoon Chan-hom track. Significant surge levels along the coast on the left side of the typhoon track were well observed in both cases, resulting from the coastal-trapped shelf waves. The Saomai track type is more likely to cause extremely high storm surges along the coast due to the stronger cumulative effect of the onshore wind forcing. The maximum wave setup was governed by the swell and slope of the sea floor. The locations of the maximum wave setup and surge level were spatially close during Typhoon Saomai, but they were separated during Typhoon Chan-hom.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 March 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology, Volume 353〈/p〉 〈p〉Author(s): Tarek Kandakji, Thomas E. Gill, Jeffrey A. Lee〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Documenting geomorphology and land use/land cover associated with the aeolian dust sources is needed to build more robust models simulating wind erosion and dust emission. It is also important to set the base for future studies aiming to quantify the effect of anthropogenic land-use change on dust emission. In this research, dust point sources were detected in the Southern Great Plains and Chihuahuan Desert regions of the United States (U.S.) for 2001–2016, encompassing a period of extreme drought. Dust points were detected using overlay analysis of brightness temperature difference images of MODIS and MODIS true color images for the days where dust plumes were visible. This study aims to identify low emission surfaces as well as high emission surfaces in terms of geomorphology and land cover. A total of 1508 dust points were detected, where 1258 points are located in the Southern Great Plains, and 187 points are located in the Chihuahuan Desert. Point pattern analysis showed a significant cluster of these points in West Texas (Nearest Neighbor Ratio = 0.33, р 〈 0.001) where cultivated lands and grasslands are the dominant land cover and aeolian sand sheet is the dominant geomorphic class. Ephemeral lakes (i.e., playas) produce the most dust sources per unit area. Cultivated croplands enclose 43% of the dust points, while shrublands and grasslands, combined, enclose 45% of the points. Results from this study confirms the importance of playas as a dynamic source of dust in southwestern U.S. Moreover, this study suggests that anthropogenic factors play a major role in dust emission within southwestern U.S, although bare lands in particular that are not subjected to anthropogenic factors (e.g., the White Sands dune field) are also emitting dust. Future research is needed to statistically analyze the contribution of different land-cover types on dust emission in the region.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 7 January 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology〈/p〉 〈p〉Author(s): Qiangshan Gao, Shijie Wang, Tao Peng, Haijun Peng, David M. Oliver〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Epikarst, defined as the “skin” of karst environment, is widely developed in southwest China, largely as a result of the subtropical monsoon climate. Typical SW China karst accommodates a dual hydrogeological structure, with surface and subsurface hydrological systems. The epikarst ecosystem of karst environments plays a key role in biogeochemical cycling and energy and material storage and transport. Due to low rates of soil-formation derived from carbonate rock weathering, the soil layer is shallow and scattered, presenting interlocked features within carbonate rock. Research on epikarst structure is primarily based on section field survey with semi-quantitative characterization, often lacking a fully quantitative description of soil-rock structural characteristics. We utilized ground penetrating radar (GPR) attributes to interpret the structure of epikarst at a peak cluster depression in the Guizhou karst plateau. Two typical types of epikarst slope profiles and one peak cluster depression in Maguan Town, Puding County were selected for study. We used MALA GPR equipment with 500 MHz and 50 MHz antennas to acquire data. GPR data was processed conventionally and then average energy attributes, average amplitude attributes and coherence attributes were extracted to interpret the structure of the two epikarst profiles and the soil depth of the depression. The results show that: (i) energy and coherence attributes can highlight the soil-rock structure of the epikarst profiles with relative ease; (ii) compared to the original returned image, the energy attributes visualise the soil and rock medium more effectively; and (iii) the coherence attributes can identify the reflection interface between complete bedrock and bedrock containing fissure and grikes (epikarst). In addition, using the 50 MHz antenna we were able to determine the soil depth in depression with coherence attributes indicating a depth of 3.6 m, very close to the real depth (3.58 m) measured by our auger verification work. GPR attributes provide evidence that the epikarst has developed a large number of fissures filled with soil or other materials, but that the bedrock under the epikarst has few fractures. GPR attributes are therefore helpful for increasing our confidence of studying the structure of slope epikarst structure and depression soil depth.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science, Volume 235〈/p〉 〈p〉Author(s): Marco Boeri, Tim A. Stojanovic, Lucy J. Wright, Niall H.K. Burton, Neal Hockley, Richard B. Bradbury〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Biodiversity is valuable to society, including through its contribution to cultural benefits: “the non-material benefits people obtain from biodiversity and ecosystem services through spiritual enrichment, cognitive development, reflection, recreation, and aesthetic experiences”. Biodiversity encompasses numerous measures, but the distinct values of these measures have been little studied. We conducted a discrete choice experiment to elicit respondents’ (n = 3000) willingness to pay for increases in four measures of bird diversity in UK coastal ecosystems: number of bird species (species richness), number of individual birds (abundance), probability of seeing rare or unusual bird species, and probability of seeing large flocks of birds (wildlife spectacles). Respondents had a positive willingness to pay (through one-time voluntary donations) for increases in all four measures (mean £3 to £5 per household). However, using latent class analysis we found considerable heterogeneity of preferences, identifying four classes of respondents with strikingly different levels of marginal willingness to pay for the four measures. Income, age, environmental activity, visits to environmental settings, and gender were important determinants of class membership. While focussing on birds, our results demonstrate the importance of a multi-dimensional conceptualisation of biodiversity in broader ecosystem management, rather than focussing on a single aspect such as species richness or abundance. Our findings also highlight the implications of heterogeneous public preferences for biodiversity for conservationists, planners, shoreline managers and developers. These need to be considered in the development of new frameworks for ecosystem services, and when planning and funding conservation actions so that the cultural benefits will accrue across a range of social groups.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science, Volume 235〈/p〉 〈p〉Author(s): Eduardo Ramírez-Romero, Juan Carlos Molinero, Ulrich Sommer, Noussaiba Salhi, Ons Kéfi - Daly Yahia, Mohamed Néjib Daly Yahia〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Structural changes in plankton primary producers have large implications for food web dynamics, energy fluxes and the vertical export of biogenic particulate carbon. Here we examine phytoplankton data spanning the period 1993–2008 from the Bay of Tunis, southwestern Mediterranean Sea, in relation to long term hydroclimate variability. We show a conspicuous shift in the structure of the phytoplankton community characterized by an increase of small-sized species and diversity loss, revealing a dominance of smaller blooming diatoms and cyanobacteria. Such changes were concurrent with marked modifications in hydroclimatic patterns experienced in the Bay of Tunis consisting of a shift towards enhanced winter precipitation together with rising temperatures. This novel study shows an overall rise in the proportion of small phytoplankton cells and a decreasing trend in phytoplankton diversity in the southern Mediterranean area. These findings warn of a potential decline of trophic efficiency and lesser food web stability resulting from mean size reduction and the diversity loss.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science, Volume 235〈/p〉 〈p〉Author(s): F. Otero-Ferrer, M. Cosme, F. Tuya, F. Espino, R. Haroun〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Similar to altitudinal gradients in terrestrial habitats, subtidal habitats experience abrupt environmental gradients across depth. The objective of this study was to understand how variation with depth of environmental factors (water temperature, light availability, water motion and sedimentation) affected the structure (size and morphology) of rhodoliths and the abundances of attached floral and faunal epibionts in a rhodolith bed at Gran Canaria Island (central-eastern Atlantic). Specifically, sampling took place seasonally at three depth strata: 18, 25 and 40 m throughout two successive years. Depth affected the size and morphology of rhodoliths, with bigger and mainly spherical nodules at 25, relative to those at 18 and 40 m depth. Larger biomasses of attached (epiphytic) macroalgae were observed at 18 and 25 m than at 40 m. The presence of hydrozoans living over rhodoliths also changed with depth, including higher abundances at 25 m than at 40 and 18 m, respectively. Wave-induced turbulence in the upper depth layer, and light intensity and sedimentation, in the lower depth layer, are the main environmental drivers regulating the presence, structure and functioning of rhodolith habitats.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 5 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science, Volume 235〈/p〉 〈p〉Author(s): Joaquín Moreno, María Ángeles Alonso, Ana Juan〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Salinity and soil moisture are considered main drivers of the plant zonation in Mediterranean saltmarshes. Therefore, both factors could have a remarkable effect on the plant functional structure of these habitats. The aim of this study was to identify the effects of abiotic and biotic factors on the plant functional structure of western Mediterranean saltmarshes. A total of 20 saltmarshes were assessed, and seven plant traits were considered. Community weighted mean and Rao index were used to measure the functional structure of the plant communities. Redundancy analysis was used to estimate the effects of soil variables on the community-weighted mean trait and functional diversity, and standardised effect size was used to assess the effect of biotic interactions. The functional traits showed a clear zonation along the salinity gradient in Mediterranean saltmarshes, mainly related to the electrical conductivity, and mainly gathered in trait syndromes. The succulent nanophanerophytes grew at the highest salinity zones. Salt excretors, both chamaephytes and mesophanerophytes, appeared in the intermediate and lowest salinity zones, respectively. Finally, geophytes with both selective cation root uptake and rhizome were mostly located in the lowest salinity zones. The abiotic factors strongly modulated the biotic interactions, and some convergence patterns were observed. The highest functional diversity was observed in the lowest salinity zones, a marked turnover. These findings indicate that multiple assembly processes determine the plant structure of Mediterranean saltmarshes, yet abiotic environmental filters strongly shape the local species assemblages and functional diversity turnover. Our results support that the whole salinity gradient should be protected to conserve the widest range of functional traits.〈/p〉〈/div〉 〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0272771419308546-fx1.jpg" width="306" alt="Image 1" title="Image 1"〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 5 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science, Volume 235〈/p〉 〈p〉Author(s): Eric Wolanski, Jonathan Lambrechts〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉The 500 km long Far Northern Great Barrier Reef (FNGBR) is a semi-enclosed sea with little connectivity with the rest of the GBR further South. Its mean circulation is controlled by the prevailing southeasterly (northwestward) wind that generates a wind-driven mean longshore flow that is enabled by an inflow of oceanic water in the South. From an examination of single-point, mid-depth current meter data at ten sites over one year, it appears that there is no net current during calm weather, which implies that the northward North Queensland Coastal Current in the adjoining Coral Sea does not intrude in the FNGBR. Only about 20–40% of the wind-driven longshore transport continues northward to exit the FNGBR through Torres Strait because of blockage by reefs, shoals and islands and by the tidal friction effect in shallow waters. The remaining 60–80% of the flow appears to be deflected seaward to the Coral Sea in the North, an observation that appears to be supported by oceanographic modelling. This situation differs from that in the central and southern Great Barrier Reef where the southward flowing East Australian Current intrudes on the shelf and generates a net current even during calm weather.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: 15 March 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology, Volume 353〈/p〉 〈p〉Author(s): Anneleen H. Geurts, Alexander C. Whittaker, Rob L. Gawthorpe, Patience A. Cowie〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Drainage networks in continental rifts are generally reported as dynamic features that produce transitions between endorheic and exorheic conditions. While this is of major importance for landscape development, sediment dispersal, and basin stratigraphy, the controls of drainage network evolution across an array of normal fault bounded basins are still not well understood. In this study we use the central Italian Apennines – an area that has been affected by active normal faulting and regional uplift over the last ~3 Myrs – to determine the controls on drainage network evolution and its impact on transient landscape evolution and basin stratigraphy. We compile previously published stratigraphic and fault-related data with new geomorphological constraints for the Aterno River system (~1300 km〈sup〉2〈/sup〉), for which a wealth of data has been collected following the destructive L'Aquila earthquake in 2009. We use this compilation to demonstrate how the different basins along the river system were initially isolated during the Early Pleistocene but became fluvially integrated with one another and the Adriatic coast between ca. 1.2 and 0.65 Ma. We conclude that the spatial and temporal pattern of drainage integration is mostly explained by a long-term increase in sediment and water supply relative to basin subsidence due to the Early to Middle Pleistocene climatic transition, the progressive increase in fault-related topography, and the transport of sediment and water down-system as drainage integration occurred. Overall we conclude that rates of sedimentation and basin subsidence in the central Apennines are well-matched, allowing tipping points between over- and under-filled conditions to be easily reached. We also show that consecutive drainage integration events produce discrete waves of river incision and terrace formation, and conclude that drainage integration is of major importance, at least equivalent to tectonics and climate, in controlling transient landscape evolution and rift basin stratigraphy.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 21 February 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology〈/p〉 〈p〉Author(s): Ning Huang, Panli He, Jie Zhang〈/p〉

Description: 〈p〉Publication date: 5 May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science, Volume 236〈/p〉 〈p〉Author(s): Penelope A. Ajani, Michaela E. Larsson, Stephen Woodcock, Ana Rubio, Hazel Farrell, Steve Brett, Shauna A. Murray〈/p〉

Description: 〈p〉Publication date: Available online 18 February 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): Lucia Fanini, Omar Defeo, Michael Elliott〈/p〉

Description: 〈p〉Publication date: Available online 19 February 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): A. Sierra, D. Jiménez-López, T. Ortega, M.C. Fernández-Puga, A. Delgado-Huertas, J. Forja〈/p〉

Description: 〈p〉Publication date: 31 May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science, Volume 237〈/p〉 〈p〉Author(s): Davood Mafi-Gholami, Eric K. Zenner, Abolfazl Jaafari, Dieu Tien Bui〈/p〉

Description: 〈p〉Publication date: Available online 19 February 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): Fatma Abdmouleh Keskes, Najla Ayadi, Abdelfattah Atoui, Mabrouka Mahfoudi, Moufida Abdennadher, Lamia Dammak Walha, Sana ben Ismail, Olfa ben Abdallah, Yosra Khammeri, Marc Pagano, Asma Hamza, Malika Belhassen〈/p〉

Description: 〈p〉Publication date: Available online 19 February 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology〈/p〉 〈p〉Author(s): Noam Greenbaum, Amit Mushkin, Naomi Porat, Rivka Amit〈/p〉

Description: 〈p〉Publication date: Available online 19 February 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology〈/p〉 〈p〉Author(s): Honghua Lu, Dengyun Wu, Huiping Zhang, Yuanxu Ma, Xiangmin Zheng, Youli Li〈/p〉

Description: 〈p〉Publication date: Available online 17 February 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): Rodrigo Torres, Brian Reid, Máximo Frangópulos, Emilio Alarcón, Magdalena Márquez, Vreni Häusermann, Günter Försterra, Gemita Pizarro, José Luis Iriarte, Humberto E. González〈/p〉

Description: 〈p〉Publication date: 5 May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science, Volume 236〈/p〉 〈p〉Author(s): Cathy Wimart-Rousseau, Katixa Lajaunie-Salla, Pierre Marrec, Thibaut Wagener, Patrick Raimbault, Véronique Lagadec, Michel Lafont, Nicole Garcia, Frédéric Diaz, Christel Pinazo, Christophe Yohia, Fabrice Garcia, Irène Xueref-Remy, Pierre-Eric Blanc, Alexandre Armengaud, Dominique Lefèvre〈/p〉

Description: 〈p〉Publication date: 1 May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology, Volume 356〈/p〉 〈p〉Author(s): Bartłomiej Wyżga, Artur Radecki-Pawlik, Tomáš Galia, Karol Plesiński, Václav Škarpich, Radek Dušek〈/p〉

Description: 〈p〉Publication date: Available online 15 February 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): H.J. Walker, Philip A. Hastings, John R. Hyde, Robert N. Lea, Owyn E. Snodgrass, Lyall F. Bellquist〈/p〉

Description: 〈p〉Publication date: Available online 14 February 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): Eric Wolanski, Gullaya Wattaykorn, Keita Furukawa, Suchana Apple Chavanich〈/p〉

Description: 〈p〉Publication date: Available online 15 February 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology〈/p〉 〈p〉Author(s): Nico Mölg, James Ferguson, Tobias Bolch, Andreas Vieli〈/p〉

Description: 〈p〉Publication date: Available online 10 February 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology〈/p〉 〈p〉Author(s): Tomasz Kalicki, Piotr Kalicki〈/p〉

Description: 〈p〉Publication date: 15 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology, Volume 355〈/p〉 〈p〉Author(s): Phllipe Wernette, Jacob Lehner, Chris Houser〈/p〉

Description: 〈p〉Publication date: Available online 8 February 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): Xianye Wang, Jianwei Sun, Zhonghao Zhao〈/p〉 〈div xml:lang="en"〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉A tidal creek represents a typical morphologic unit in an intertidal flat. The development and migration of a tidal creek can affect the mass transport, ecological environment, and geomorphologic evolution of the flat. By using field observations, this study links hydrodynamics, sediment transport processes with short-term changes in topography at a typical tidal creek system located at the Chongming Island of the Yangtze River estuary. Hydrodynamic and sediment transport associated with varying tidal cycles across both wet (flood) and dry seasons were measured through the field campaign. The wet and dry seasons represent higher and lower discharges of Yangtze River, respectively. The results indicated that most of the suspended sediment becomes entrained at the beginning of a flood tide. At a fixed point, 7.2 times of suspended sediments, which were entrained out of the creek in wet season, began to be transported along the creek compared to dry season. In the dry season, high flow velocity and shear stress conditions occurred in the tidal creek because the water level was below the top of the flat. In summary, the tidal creeks were found to serve as effective conduits for the transportation of sediments in the wet season, and the secondary flow enhanced the development of tidal meandering. Seasonal variations in creek morphological changes were also continuously monitored over two years at intervals of two months. The change of creek morphology varied from the high level to low level, and tidal meandering was strongly associated with flood and ebb tides.〈/p〉〈/div〉 〈/div〉

Description: 〈p〉Publication date: Available online 8 February 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Estuarine, Coastal and Shelf Science〈/p〉 〈p〉Author(s): Nino Krvavica, Igor Ružić〈/p〉 〈h5〉Abstract〈/h5〉 〈div〉〈p〉Understanding the response of estuaries to sea-level rise is crucial in developing a suitable mitigation and climate change adaptation strategy. This study investigates the impacts of rising sea levels on salinity intrusion in salt-wedge estuaries. The sea-level rise impacts are assessed in idealized estuaries using simple expressions derived from a two-layer hydraulic theory, and in the Neretva River Estuary in Croatia using a two-layer time-dependent model. The assessment is based on three indicators - the salt-wedge intrusion length, the seawater volume, and the river inflows needed to restore the baseline intrusion. The potential SLR was found to increase all three considered indicators. Theoretical analysis in idealized estuaries suggests that shallower estuaries are more sensitive to SLR. Numerical results for the Neretva River Estuary showed that SLR may increase salt-wedge intrusion length, volume, and corrective river inflow. However, the results are highly non-linear because of the channel geometry, especially for lower river inflows. A theoretical assessment of channel bed slope impacts on limiting a potential intrusion is therefore additionally discussed. This findings emphasize the need to use several different indicators when assessing SLR impacts.〈/p〉〈/div〉 〈h5〉Graphical abstract〈/h5〉 〈div〉〈p〉〈figure〉〈img src="https://ars.els-cdn.com/content/image/1-s2.0-S0272771419308972-fx1.jpg" width="500" alt="Graphical abstract for this article" title=""〉〈/figure〉〈/p〉〈/div〉

Description: 〈p〉Publication date: 15 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology, Volume 355〈/p〉 〈p〉Author(s): Shahram Bahrami, Domenico Capolongo, Mohammad Rahdan Mofrad〈/p〉

Description: 〈p〉Publication date: 15 April 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology, Volume 355〈/p〉 〈p〉Author(s): Taylor Rowley, Mick Ursic, Kory Konsoer, Eddy Langendon, Mike Mutschler, Josh Sampey, Pawel Pocwiardowski〈/p〉

Description: 〈p〉Publication date: 1 May 2020〈/p〉 〈p〉〈b〉Source:〈/b〉 Geomorphology, Volume 356〈/p〉 〈p〉Author(s): Tao Zhang, Minquan Feng, Kailin Chen〈/p〉