The role of the Río de la Plata bottom salinity front in accumulating debris

The Río de la Plata, one of the most important South American estuarine environments, is characterized by a bottom salinity front that generates an ecotone between the river and the estuary. Based on bottom trawls and costal sampling we describe the distribution, types, and amount of debris found in the bottom and shoreline across this front. Plastics and plastic bags were the main debris types in both areas. Concentrations of total debris upriver the front were always significantly higher than downriver the front showing that the front acts as a barrier accumulating debris. Moreover, a large part of debris end ups accumulated in the coastal area upriver the frontal position. This area is particularly sensitive because the coastline encompasses an UNESCO Man and the Biosphere Reserve and a Ramsar site, and due to the ecological significance of the front for many valuable species.     

Numerical Study on the Effect of the Manila Seismic Tsunami on the Guangdong Coast——The Nonlinear Effects of Tides and Tsunamis

The coupling numerical model between astronomical tide and tsunamis was built based on the data of the COMCOT model, which was verified by the Japan "3·11" tsunami. The tsunami source of the Manila seismic tsunami was designed and computed to analyze the risk of tsunami which will happen in the Guangdong coast. According to the results, the maximum quantity of water increasing and the time of the tsunami arriving at the Guangdong seacoast were calculated. The coupling simulation between astronomical tide and tsunamis has significant meaning for evaluating the risk and early-warning of tsunamis in the Guangdong coastal area.     

Study of a model for correcting the effects of horizontal advection on surface fluxes measurement based on remote sensing

As well known, the methods of remote sensing and Bowen Ratio for retrieving surface flux are based on energy balance closure; however, in most cases, surface energy observed in experiment is lack of closure. There are two main causes for this: one is from the errors of the observation devices and the differences of their observational scale; the other lies in the effect of horizontal advection on the surface flux measurement. Therefore, it is very important to estimate the effects of horizontal advection quantitatively. Based on the local advection theory and the surface experiment, a model has been proposed for correcting the effect of horizontal advection on surface flux measurement, in which the relationship between the fetch of the measurement and pixel size for remote sensed data was considered. By means of numerical simulations, the sensitivities of the main parameters in the model and the scaling problems of horizontal advection were analyzed. At last, by using the observational data acquired in agricultural field with relatively homogeneous surface, the model was validated.     

Intercalibration of the Servicio Nacional de Geología y Minería (SERNAGEOMIN), Chile and WiscAr 40Ar/39Ar laboratories for Quaternary dating

Accurate and precise dating of Quaternary lavas and pyroclastic flow or fall deposits is essential for understanding the evolution of active volcanoes and providing context for future eruptions and hazard assessment. The ⁴⁰Ar/³⁹Ar method is commonly employed to date these volcanic materials, however, dating young (<150 ka) K₂O-poor materials can be challenging owing to low radiogenic ⁴⁰Ar* contents that can be difficult to distinguish from trapped atmospheric argon. To address this challenge, a collaborative intercalibration exercise involving the University of Wisconsin-Madison WiscAr Laboratory and the ⁴⁰Ar/³⁹Ar Laboratory of the Servicio Nacional de Geología y Minería (SERNAGEOMIN), Chile was conducted on a common set of samples with the aim of refining our methods and optimizing precision and accuracy of age determinations. Groundmass and plagioclase samples were analyzed on a 5-collector Noblesse ion counting mass spectrometer in the WiscAr lab, whereas measurements in the SERNAGEOMIN lab were performed using an ARGUS VI spectrometer equipped with faraday detectors and one compact discrete dynode electron multiplier. Samples for the intercalibration were collected jointly from three Andean Southern Volcanic Zone volcanoes to evaluate the capability of each laboratory to date different materials. Samples from lava flows with 1.0–3.2 wt % K₂O from Planchon-Peteroa volcanic complex and with <1.0 wt % K₂O from Calbuco Volcano that are the focus of ongoing geological studies were measured in both laboratories. Single crystals of plagioclase (0.6–1.0 wt% K₂O) were measured from the voluminous Diamante (Pudahuel) ignimbrite sourced from the Diamante Caldera. Multiple rounds of experiments were conducted including co-irradiation of samples at Oregon State University, as well as irradiations using the CCHEN reactor in Chile to investigate differences in neutron fluence parameters. As a result, SERNAGEOMIN has modified long-used protocols for the CCHEN reactor so that Quaternary samples may be irradiated for periods of time most appropriate for their age. Although less precise than plateau ages, the isochron ages generated in the two laboratories agree at 2σ for each sample. Six of six co-irradiated samples from Planchon-Peteroa yield plateau ages that also show inter-lab agreement at 2σ. The low K₂O lavas from Calbuco proved more challenging with only three out of five plateau ages in agreement between labs. SERNAGEOMIN blanks were higher and more variable in Calbuco experiments, thus, differences in the variability of the measured ³⁶Ar blanks between the two laboratories may explain the discrepancy in plateau ages. Analysis of single plagioclase crystals from the Diamante Ignimbrite show excellent agreement between labs for both weighted mean apparent ages and isochron ages. We favor an isochron age for the ignimbrite of 132.4 ± 2.2 ka, however, discrepancies in results between samples from three different outcrops present an interesting geochronologic problem that warrants further study. Overall, the consistency of the results between labs is promising. These new precise age determinations significantly improve our understanding of the temporal evolution of these active volcanoes.     

Fuzzy Optimization Neural Network Approach for Ice Forecast in the Inner Mongolia Reach of the Yellow River/Approche d'Optimisation Floue de Réseau de Neurones pour la Prévision de la Glace Dans le Tronçon de Mongolie Intérieure du Fleuve Jaune

Abstract

In ice forecasting, a key problem is the forecast of freeze-up and break-up dates. Ice-water mechanics and the principle of heat-exchange were mainly adopted in previous research. However, the mathematical models in these studies are complex and many parameters are required in relation to upstream and/or downstream gauging stations. Moreover, too many assumptions or simplifications for these parameters and constraints directly lead to low accuracy of the models and limitations as to their practical applications. This paper develops a fuzzy optimization neural network approach for the forecast of freeze-up date and break-up date. The Inner Mongolia reach lies in the top north of the Yellow River, China. Almost every year ice floods occur because of its special geographical location, hydrometeorological conditions and river course characteristics. Therefore, it is of particular importance for ice flood prevention to forecast freeze-up date and break-up date accurately. A case study in this region shows that the proposed methodology may allow obtaining useful results.     

Accounting for sparsely observed rainfall space—time variability in a rainfall—runoff model of a semiarid Tunisian basin/Prise en compte d'observations peu denses de la variabilité spatiotemporelle de la pluie dans une modélisation pluie—débit d'un bassin semi-aride Tunisien

Abstract

The management of water excesses and deficits is a major task in semiarid Mediterranean regions, where the variability of rainfall inputs is high at different time and space scales. Thus intense hydrometeorological events, which generate both potential resource and hazards, are of major interest. A simple method is proposed, with the example of the Skhira basin (192 km²) in central Tunisia, to account for the event space–time variability of rainfall in a rainfall–runoff model, in order to check its influence on the shape, magnitude and timing of resulting hydrographs. The transfer function used is a geomorphology-based unit hydrograph with an explicit territorial significance. Simulations made for highly variable events show the relevance of this method, seen as the first step of a downward approach, and its robustness with respect to the quality and the density of rainfall data.     

Utility of high-resolution climate model simulations for water resources prediction over the Korean Peninsula: a sensitivity study / Utilité de simulations de modèle climatique à haute résolution pour la prévision des ressources en eau dans la Péninsule Coréenne: étude de sensibilité

Abstract

Abstract The utility of simulations of Global Climate Models (GCMs) for regional water resources prediction and management on the Korean Peninsula was assessed by a probabilistic measure. Global Climate Model simulations of an indicator variable (e.g. surface precipitation or temperature) were used for discriminating high vs low regional observations of a target variable (e.g. watershed precipitation or reservoir inflow). The formulation uses the significance probability of the Kolmogorov-Smirnov test for detecting differences between two distributions. High resolution Atmospheric Model Intercomparison Project-II (AMIP-II) type GCM simulations performed by the European Centre for Medium-Range Weather Forecasts (ECMWF) and AMIP-I type GCM simulations performed by the Korean Meteorological Research Institute (METRI) were used to obtain information for the indicator variables. Observed mean areal precipitation and temperature, and watershed-outlet discharge values for seven major river basins in Korea were used as the target variables. The results suggest that the use of the climate model nodal output from both climate models in the vicinity of the target basin with monthly resolution will be beneficial for water resources planning and management analysis that depends on watershed mean areal precipitation and temperature, and outlet discharge.