Equilibrium in geomorphology: geosystems, floodplains and morfodynamics of the Jacaré-Pepira and Jacaré-Guaçu rivers (São Paulo, Brazil)

Author(s)

Éverton Vinícius Valezio

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Geociências
• Defense date: 2016-08-26

Examining board members

Archimedes Perez Filho; Francisco Sérgio Bernardes Ladeira; Norberto Morales

• Advisor: Archimedes Perez Filho

Abstract

Transformations in river-plain systems indicate moments of instability in its elements, facing changes in matter and energy. As the river channel is an important receptor of such changes, this study aimed to analyze and interpret, from an evolutionary and dynamic approach, the transformations in the morphology of rivers Jacaré-Pepira and Jacaré-Guaçu (São Paulo - Brazil) and in their respective floodplains. Our methodology included the analysis of their morphometric indexes ¿ longitudinal profile, SL Index (Stream Gradient-Length Index), the basins asymmetry factors and topographic transverse asymmetry; the analysis and interpretation of orbital and non-orbital images; and the dating of fluvial deposits through the use of Optically Stimulated Luminescence (OSL). Results show the presence of three meander generations and the formation of two levels of low river terraces (T1 and T2), established during the Late Pleistocene and the Holocene. They also show an active process of change in meander bends in the last 50 years, with preponderant mechanisms of cutoofs, motivated by the action of allogenic factors (tectonics and climate). Such factors shift the main channels from their central axes in both hydrographic basins by the tilting of blocks, with considerable action for the NE axis and predominance of low terraces in the left bank. Other factors include the formation, sculpturing and linear dissection of river channels by different Quaternary climatic pulses, as well as authigenic processes (self-regulation), with the systematic cutting of meander curves to reduce sinuosity. The intense transformations recorded in the landscape in a very short time period point to the prevailing condition of imbalance in the physical systems of the studied rivers, with striking disruptions in geomorphological thresholds (AU)

• FAPESP's process: 13/24885-1 - Equilibrium in geomorphology: geosystems, floodplains and morfodynamic of Jacaré-Pepira and Jacaré-Guaçu rivers/SP
• Grantee: Éverton Vinícius Valezio
• Support Opportunities: Scholarships in Brazil - Master