Abstract. The e-Science environment developed in the framework of the EU-funded DRIHM project was used to demonstrate its ability to provide relevant, meaningful hydrometeorological forecasts. This was illustrated for the tragic case of 4 November 2011, when Genoa, Italy, was flooded as the result of heavy, convective precipitation that inundated the Bisagno catchment. The Meteorological Model Bridge (MMB), an innovative software component developed within the DRIHM project for the interoperability of meteorological and hydrological models, is a key component of the DRIHM e-Science environment. The MMB allowed three different rainfall-discharge models (DRiFt, RIBS and HBV) to be driven by four mesoscale limited-area atmospheric models (WRF-NMM, WRF-ARW, Meso-NH and AROME) and a downscaling algorithm (Rain-FARM) in a seamless fashion. In addition to this multi-model configuration, some of the models were run in probabilistic mode, thus giving a comprehensive account of modelling errors and a very large amount of likely hydrometeorological scenarios ( > 1500). The multi-model approach proved to be necessary because, whilst various aspects of the event were successfully simulated by different models, none of the models reproduced all of these aspects correctly. It was shown that the resulting set of simulations helped identify key atmospheric processes responsible for the large rainfall accumulations over the Bisagno basin. The DRIHM e-Science environment facilitated an evaluation of the sensitivity to atmospheric and hydrological modelling errors. This showed that both had a significant impact on predicted discharges, the former being larger than the latter. Finally, the usefulness of the set of hydrometeorological simulations was assessed from a flash flood early-warning perspective.

We propose a technique for simplification and multiresolution modeling of a terrain represented as a TIN. Our goal is to maintain the morphological structure of the terrain in the resulting multiresolution model. To this aim, we extend Morse theory, developed for continuous and differentiable functions, to the case of piecewise linear functions. We decompose a TIN into areas with uniform morphological properties (such as valleys, basins, etc.) separated by a network of critical lines and points. We describe an algorithm to compute the above decomposition and the critical net, and a TIN simplification algorithm that preserves them. On this basis, we build a multiresolution terrain model, which provides a representation of critical features at any level of detail

Abstract. In this paper, we address the problem of analyzing the topology of discrete scalar fields defined on triangulated domains. To this aim, we introduce the notions of discrete gradient vector field and of Smalelike decomposition for the domain of a d-dimensional scalar field. We use such notions to extract the most relevant features representing the topology of the field. We describe a decomposition algorithm, which is independent of the dimension of the scalar field, and, based on it, methods for extracting the critical net of a scalar field. A complete classification of the critical points of a 2-dimensional field that corresponds to a piecewise differentiable field is also presented.

This paper seeks to move towards an un-encoded metadata standard supporting the description of environmental numerical models and their interfaces with other such models. Building on formal metadata standards and supported by the local standards applied by modelling frameworks, the desire is to produce a solution, which is as simple as possible yet meets the requirements to support model coupling processes. The purpose of this metadata is to allow environmental numerical models, with a first application for a hydro-meteorological model chain, to be discovered and then an initial evaluation made of their suitability for use, in particular for integrated model compositions. The method applied is to begin with the ISO19115 standard and add extensions suitable for environmental numerical models in general. Further extensions are considered pertaining to model interface parameters (or phenomena) together with spatial and temporal characteristics supported by feature types from climate science modelling language. Successful validation of parameters depends heavily on the existence of controlled vocabularies. The metadata structure formulated has been designed to strike the right balance between simplicity and supporting the purposes drawn out by interfacing the Real-time Interactive Basin Simulator hydrological model to meteorological and hydraulic models and, as such, successfully provides an initial level of information to the user.Quillon Harpham (corresponding author) HR Wallingford,

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