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In the world, there are very few experiences of studies oriented to the integral evaluation of risks due to natural hazards. In the case of volcanic risk, most of the scientific-technical and economic efforts have been oriented mainly toward the evaluation of threats, with few methodological considerations to assess vulnerability and much less risk. In other cases, the threat and vulnerability are evaluated independently, with many difficulties for the comprehensive risk assessment. Many of the studies called "vulnerability assessments" are only physical and functional characterizations and diagnoses of vital infrastructure and population. These characterizations can hardly be interpreted in terms of georeferenced indices and/or vulnerability maps that represent the spatial and temporal exposure of the elements exposed to each threat and, even less, that represent the intrinsic and extrinsic response capacities of these elements in comparison with the threats. In this chapter, a new conceptual and methodological approach is proposed for the integral evaluation of volcanic risk, which includes the generation and adjustment of a new equation for the determination of volcanic risk, based on the integral assessment of threats and vulnerabilities.

The Canal del Dique, located on the Colombian Caribbean Coast, can be seen as an "artificial" branch of the River Magdalena. Since its inception in 1650, it has undergone a series of interventions aimed at optimising river navigation between Cartagena and the interior of the country, little consideration having been paid to institutional, economic, social and environmental impacts. This paper presents a systemic assessment of environmental impact (SAEI) methodology, based on systemic parameterisation of the environment, proposed by Vega [2011], for the strategic environmental assessment of policy, plans, programmes or large-scale projects, considering a case study of the Canal del Dique environmental rehabilitation as proposed by the Colombian government. Information arising from the framework of an inter-administrative agreement between the Universidad Nacional de Colombia and the Regional Autonomous Corporation for the Rio Grande de la Magdalena (CORMAGDALENA) was used for studying the environmental restoration of and navigation in the Canal del Dique [UN-LEH, 2008]. The authors developed and summarised SAEI regarding six alternatives for hydrosedimentological management in the canal to obtain results concerning environmental impairment or improvement regarding each factor considered, and the degree of aggressiveness or betterment involved in each alternative. Alternative 4, an enhanced version of current condition (ECC) would have produced the greatest environmental benefit (i.e. limited dredging plus optimising channel-wetland interconnection) requiring the narrowing of three straight reaches along the canal and the construction of a sluice-gate system in the Strait of Paracuica (near the town of El Recreo).