The effect of long-term and decadal climate and hydrology variations on estuarine marsh dynamics: An identifying case study from the Río de la Plata

The vertical growth of coastal wetlands is known to primarily be controlled by local tidal range and sediment availability as well as the occurrence of storm events. In estuaries, sediment availability additionally depends on riverine sediment input, the effect of which may be more pronounced in some parts of the estuary, thereby introducing a distinct spatial pattern that depends on the estuary's shape as well as the riverine sediment input and the hydro-meteorological regime. In the present study, we investigate how estuarine marshes along the whole Río de la Plata (RdlP) are affected by decadal and long-term variations in river discharge and storm activity. The El Niño Southern Oscillation (ENSO), in this context, appears to introduce a pronounced decadal variability on sediment loads brought into the RdlP. Based on 15 sediment cores, recovered along the RdlP and adjacent Atlantic coast, vertical marsh growth rates were studied using radionuclide dating (210Pb and 137Cs) and grain size distributions. By comparing these sedimentological records with historic river discharge and storm surge data, we spatially interpret the relative importance of temporal variations in river discharge and storm activity on estuarine marsh growth. By delivering the first estimates for vertical growth rates of the RdlP marshes, we conclude that with average vertical marsh growth rates between 0.4 and 2.6 cm year− 1, the RdlP marshes are highly resilient against drowning under present and future sea-level rise (SLR) conditions. Furthermore, our results confirm a large spatial variability of the drivers for vertical marsh growth; extreme storm surges appear to play a role in the development of the outer RdlP marshes whereas the temporal variations in river discharge seem to be hierarchically more important for the marshes in the inner estuary.This project was financially supported by a grant of the Cluster of Excellence 80 ‘The Future Ocean’ to Mark Schuerch (grant CP1211). ‘The Future Ocean’ is funded within the framework of the Excellence Initiative by the ‘Deutsche Forschungsgemeinschaft’ (DFG) on behalf of the German federal and state governments (EXC 80). Felipe García-Rodríguez acknowledges ‘Agencia Nacional de Investigación e Innovación’ (ANII) and PEDECIBA. Jan Scholten acknowledges the support provided by the FP7 EU Marie Curie Career Integration Grant (grant PCIG09-GA-2011-293499).This is the author accepted manuscript. The final version is available from Elsevier at http://dx.doi.org/10.1016/j.geomorph.2016.06.029

The effect of long-term and decadal climate and hydrology variations on estuarine marsh dynamics: an identifying case study from the Río de la Plata

The vertical growth of coastal wetlands is known to primarily be controlled by local tidal range and sediment availability as well as the occurrence of storm events. In estuaries, sediment availability additionally depends on riverine sediment input, the effect of which may be more pronounced in some parts of the estuary, thereby introducing a distinct spatial pattern that depends on the estuary's shape as well as the riverine sediment input and the hydro-meteorological regime. In the present study, we investigate how estuarine marshes along the whole Rio de la Plata (RdlP) are affected by decadal and long-term variations in river discharge and storm activity. The El Nino Southern Oscillation (ENSO), in this context, appears to introduce a pronounced decadal variability on sediment loads brought into the RdlP. Based on 15 sediment cores, recovered along the RdlP and adjacent Atlantic coast, vertical marsh growth rates were studied using radionuclide dating (210Pb and 137Cs) and grain size distributions. By comparing these sedimentological records with historic river discharge and storm surge data, we spatially interpret the relative importance of temporal variations in river discharge and storm activity on estuarine marsh growth. By delivering the first estimates for vertical growth rates of the RdlP marshes, we conclude that with average vertical marsh growth rates between 0.4 and 2.6 cm year− 1, the RdlP marshes are highly resilient against drowning under present and future sea-level rise (SLR) conditions. Furthermore, our results confirm a large spatial variability of the drivers for vertical marsh growth; extreme storm surges appear to play a role in the development of the outer RdlP marshes whereas the temporal variations in river discharge seem to be hierarchically more important for the marshes in the inner estuary.Facultad de Ciencias Naturales y Muse

Investigating compound flooding in an estuary using hydrodynamic modelling: A case study from the Shoalhaven River, Australia

Many previous modelling studies have considered storm-tide and riverine flooding independently, even though joint-probability analysis highlighted significant dependence between extreme rainfall and extreme storm surges in estuarine environments. This study investigates compound flooding by quantifying horizontal and vertical differences in coastal flood risk estimates resulting from a separation of storm-tide and riverine flooding processes. We used an open-source version of the Delft3D model to simulate flood extent and inundation depth due to a storm event that occurred in June 2016 in the Shoalhaven Estuary, south-eastern Australia. Time series of observed water levels and discharge measurements are used to force model boundaries, whereas observational data such as satellite imagery, aerial photographs, tidal gauges and water level logger measurements are used to validate modelling results. The comparison of simulation results including and excluding riverine discharge demonstrated large differences in modelled flood extents and inundation depths. A flood risk assessment accounting only for storm-tide flooding would have underestimated the flood extent of the June 2016 storm event by 30 % (20.5 km2). Furthermore, inundation depths would have been underestimated on average by 0.34 m and by up to 1.5 m locally. We recommend considering storm-tide and riverine flooding processes jointly in estuaries with large catchment areas, which are known to have a quick response time to extreme rainfall. In addition, comparison of different boundary set-ups at the intermittent entrance in Shoalhaven Heads indicated that a permanent opening, in order to reduce exposure to riverine flooding, would increase tidal range and exposure to both storm-tide flooding and wave action

Differential adoption of castration‐resistant prostate cancer treatment across facilities in a national healthcare system

Over the past decade, abiraterone and enzalutamide have largely replaced ketoconazole as oral treatments for castration-resistant prostate cancer (CRPC). We investigated the differential adoption of abiraterone and enzalutamide across facilities in a national healthcare system to understand the impact a facility has on the receipt of these novel therapies. Using data from the VA Corporate Data Warehouse, we identified a cohort of men with CRPC who received the most common first-line therapies: abiraterone, enzalutamide, docetaxel, or ketoconazole between 2010 and 2017. We described variability in the adoption of abiraterone and enzalutamide across facilities by time period (2010-2013 or 2014-2017). We categorized facilities depending on the timing of adoption of abiraterone and enzalutamide relative to other facilities and described facility characteristics associated with early and late adoption. We identified 4998 men treated with ketoconazole, docetaxel, abiraterone, or enzalutamide as first-line CRPC therapy between 2010 and 2017 at 125 national facilities. When limiting the cohort to oral therapies, most patients treated earlier in the study period (2010-2013) received ketoconazole. A dramatic shift was seen by the second half of the study period (2014-2017) with most men treated with first-line abiraterone (61%). Despite this shift and a new standard of care, some facilities persisted in the widespread use of ketoconazole in the later period, so-called late adopting facilities. After multivariable adjustment, patients who received treatment at a late adopting facility were more likely receiving care at a lower complexity, rural facility, with less urology and hematology/oncology workforce (all p < 0.01). Many facilities persisted in their use of ketoconazole as first-line CRPC therapy, even when other facilities had adopted the new standard of care abiraterone and enzalutamide. Further work is needed to identify the effect of this late adoption on outcomes important to patients