Mapping socio-environmental vulnerability to hydrological risks: floods in Bragança Paulista - São Paulo State

Author(s)

Franciele Caroline Guerra

• Document type: Master's Dissertation
• Press: Rio Claro. 2020-07-07.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Geociências e Ciências Exatas. Rio Claro
• Defense date: 2020-05-07
• Advisor: Andréa Aparecida Zacharias

Abstract

A series of interrelated disasters have currently gained prominence over the Brazil and worldwide, gathering episodes that have resulted in increasing losses, both human and economic, related to risks and their consequences. The urbanization process, along with degree of saturation, soil imperviousness, rectification and improper settlement on hillslopes and near to the rivers, have contributed to an increasing impact of floods and several human-induced processes that lead to socio-environmental risk. In the last five decades, there have been more than ten thousand deaths caused by natural disasters, most of them related to floods and landslide. The magnitude of a disaster is related to social, economic and demographic phenomena, among others, and contributes to increasing the population's vulnerability and exposure. We analyzed the Lavapés Administrative Region, a macrozone encompassing the urban area of Bragança Paulista/SP municipality. The city of Bragança Paulista have suffered, historically, a plenty of socioeconomic and environmental issues. The increasing intensity and frequency of the floods are noteworthy due to extensive impervious cover, since large water volumes that were previously infiltrating, now become part of the surface runoff. The main objective here relies on the spatial distribution of socio-environmental vulnerability related to hydrological risks, particularly floods, considering the triggering factors in urban areas. The methodological procedures are comprised of: (a) literature review and public data collection; (b) mapping the slope classes; (c) supervised classification of vegetation cover and land use; (d) collection and selection of demographic census data, weighting variables based on criteria of criticality and support capacity applied to the social vulnerability; (e) application of Exploratory Factor Analysis (EFA) to summarize data; (f) Principal Component Analysis (PCA) applied to socioeconomic, demographic and environmental data; (g) interpretation of the statistical results produced by EFA model; (h) fieldwork validation; and finally, (i) data integration using the Analytic Hierarchy Process (AHP) method, a multicriteria analysis to rank information for the preparation of synthesis cartography. The data integration regarding fieldwork data and different thematic maps supported the final synthesis mapping, then producing the scenario of socio-environmental vulnerability to floods. These results support a broader view of landscape aiming mitigating measures to a better municipal management. Through the spatial analysis of socio-environmental vulnerability, the most and least vulnerable areas to floods were characterized, which allowed the establishment of urbanization patterns that promote and stopped these processes. The spatial distribution of social vulnerability reflected a tendency of peripheral areas having high vulnerability, obeying the pattern of center-periphery opposition. Finally, the understanding concerning the role of socio-environmental vulnerability at municipal level is a crucial ability for the stakeholders to adopt and establish policies and actions to prevent, alert, mitigate and recover the most vulnerable areas. (AU)

• FAPESP's process: 17/00564-2 - Mapping of risk areas the movement of hydrological and mass: a case study in the city of Bragança Paulista/SP
• Grantee: Franciele Caroline Guerra
• Support type: Scholarships in Brazil - Master