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Hindcasting of past levee failures enhances insights in the performance and vulnerability of levees. The scarcity of field evidence makes identifying the cause(s) of failure difficult. Under these circumstances, multiple scenarios and model choices are possible to characterise and to model the failure. This paper shows how probabilistic Bayesian techniques advance the procedure of hindcasting of levee failures. In the developed approach, a-priori levee information, and failure observations are systematically taken into account to determine the most likely scenario and the most representative model choices to characterise the failure most accurately. Observations, such as the slip surface, are taken into account in the probability estimates. The levee failure near Breitenhagen, Germany (2013) is used as a case study. The levee failed during river floods due the instability of the landside slope. The levee failure was most likely triggered by locally weak soil conditions and unexpected high water pressures due a connection between a pond on the riverside of the levee and the aquifer. These conditions were likely caused by the occurrence of a previous breach at this location. The approach developed in this paper is expected to support a more systematic and objective method of analysis of other levee failures. [ABSTRACT FROM AUTHOR]

Cannibalism is known to be a significant source of natural mortality of young North-east Arctic (NEA) cod. Cannibalism data, starting from 1984, have been used in NEA cod stock assessments since 1995, which has led to inconsistency in the cod abundance time series from 1946 to the present. To address this inconsistency, this study estimates the cannibalism-induced mortality (M2) of NEA cod at age 3–5 for the period 1946–1983. Combined qualitative and quantitative cod stomach content data for 1984–2010 were used to make the M2 estimations for age groups 3–5 (ICES 2014), then different factors including SSB were used to examine which covariates explained variability in M2 and thus make predictions for 1946–1983. The level of cannibalism was estimated to be high in the 1950s – early1960s. VPA-based assessment was run using these estimated M2 values. As a result, numbers of cod eaten by their conspecifics in the historical period and new increased recruitment estimates at age 3 were computed. The main factors affecting cannibalism appeared to be young cod abundance, total stock biomass (TSB) of large cod, and capelin total stock biomass (which represents an alternative prey). The problems involved in using the new recruitment time series in fishery management are discussed. The methodology presented here represents a generic approach to extending predation mortalities back in time to improve historical stock estimates. [ABSTRACT FROM PUBLISHER]

In this study, a two-dimensional storm surges/tide prediction model called the Storm surges/Tide Operational Model (STORM) was developed and applied as the operational forecast model of the Korea Meteorological Administration (KMA). STORM has good horizontal resolution (8 km) and accounts for the interaction between tides and storm surges. This model has been implemented for the northwestern Pacific Ocean including the area around the Korean Peninsula. To examine the model performance, a hindcasting experiment was carried out for Typhoon Maemi. The results showed good agreement between the simulation and observation. The operational model results were also verified for two years (June 2005-June 2007) using observed sea level data from tidal stations around the Korean Peninsula. Comparisons of modeled and observed sea level revealed larger differences at the western coast of Korea than at the southern and eastern coasts. The seasonal variations of bias and root mean square error (RMSE) between the modeled and observed sea levels generally showed small differences in summer and large differences in winter. The average bias, RMSE, and correlation coefficients for 12 total stations between modeled and observed values were -0.13 m (-0.14 m), 0.47 m (0.47 m), and 0.79 (0.78) for 24-hour (48-hour) forecasts. [ABSTRACT FROM AUTHOR]

Typhoon Maemi crossed the south coast of Korea at 21LST, September 12, 2003, where its storm surge accompanied by high waves and astronomical high tide induced the most severe coastal disaster in Korea. In particular, Masan City facing Masan Bay had the worst damages from the storm surge flooding with the maximum surge height of ∼230 cm recorded at Masan Port. In order to obtain the design surge heights for the coastal structures in Masan City, a hindcasting study of storm surge for Typhoon Maemi was conducted using a fine-scale regional surge model which was connected to the larger scale surge models by a nested grid system. The sea surface pressure and wind fields were computed by a primitive vortex wind model to obtain the input data for the storm surge model. The hindcasted surge heights were compared with the observed surges at Masan Port as well as at the major tide stations on the south coast of Korea. The hindcasted surges were in a good agreement with the observed surges for both the maximum heights and the occurrence times. [ABSTRACT FROM AUTHOR]