An interactive web-GIS tool for risk analysis: a case study in the Fella River basin, Italy

This paper presents a prototype of an interactive web-GIS tool for risk analysis of natural hazards, in particular for floods and landslides, based on open-source geospatial software and technologies. The aim of the presented tool is to assist the experts (risk managers) in analysing the impacts and consequences of a certain hazard event in a considered region, providing an essential input to the decision-making process in the selection of risk management strategies by responsible authorities and decision makers. This tool is based on the Boundless (OpenGeo Suite) framework and its client-side environment for prototype development, and it is one of the main modules of a web-based collaborative decision support platform in risk management. Within this platform, the users can import necessary maps and information to analyse areas at risk. Based on provided information and parameters, loss scenarios (amount of damages and number of fatalities) of a hazard event are generated on the fly and visualized interactively within the web-GIS interface of the platform. The annualized risk is calculated based on the combination of resultant loss scenarios with different return periods of the hazard event. The application of this developed prototype is demonstrated using a regional data set from one of the case study sites, Fella River of northeastern Italy, of the Marie Curie ITN CHANGES project.

Sulfur and strontium isotope composition of the Llobregat River (NE Spain): Tracers of natural and anthropogenic chemicals in stream waters

The use of sulfur and strontium isotopes as tracers for the source/s of water contaminants have been applied to the water of the Llobregat River system (NE Spain). Surface water samples from June 1997 were collected from the Llobregat River and its main tributaries and creeks. The chemistry of most stream waters are controlled mainly by the weathering of Tertiary chemical sediments within the drainage basin. The largest variation in delta(34)S values were found in the small creeks with values ranging from -9.9 to 15parts per thousand, whilst in the main river channels values ranged from 6.3 to 12.4parts per thousand. The Sr-87/Sr-86 ratio for dissolved strontium ranged from 0.70795 for a non-polluted site to 0.70882 for a polluted one. Most of the waters with high NO3 and low Ca/Na ratio converge to the same Sr-87/Sr-86 value, pointing to dominant pollutant end member contribution or a mixing of pollutants with an isotopic composition around 0.7083-0.7085. Although the concentration of the natural inputs in the river for sulfate and strontium are high, as a result of the sulfate outcrops within the geology of the basin, their isotopic characteristics suggest that they can be used as a discriminating device in water pollution problems. However to establish the detailed characteristics of the isotopes as geochemical tools, specific high-resolution case studies are necessary in small areas, where the inputs are well known.