Temporal and spatial adjustments of channel migration and planform geometry: responses to ENSO driven climate anomalies on the tropical freely-meandering Aguapei River, SAo Paulo, Brazil

Author(s)

Suizu, Taina Medeiros ^[1] ; Nanson, Gerald C. ^[2]

Affiliation

^[1] Univ Estadual Paulista UNESP, Programa Posgrad Geog, Campus Presidente Prudente, Sao Paulo - Brazil

^[2] Univ Wollongong, Sch Earth & Environm Sci, Wollongong, NSW - Australia

• Document type: Journal article
• Source: EARTH SURFACE PROCESSES AND LANDFORMS; v. 43, n. 8, p. 1636-1647, JUN 30 2018.
• Web of Science Citations: 3

Abstract

Two reaches of Aguapei River, a left-bank tributary of the Parana River in western SAo Paulo state, Brazil, were studied with the objective of assessing the role of bend curvature on channel migration in this wet-tropical system and examining if land-use changes or ENSO (El Nino Southern Oscillation) driven climate anomalies over nearly half a century have changed migration behaviour and planform geometry. Meander-bend migration rates and morphometric parameters including meander-bend curvature, sinuosity, meander wavelength and channel width, were measured and the frequency of bend cutoffs was analysed in order to determine the rate of change of channel adjustment over a 48year period to 2010. Results show that maximum average channel migration rates occur in bends with curvatures of about 2-3 r(c)/w, similar to other previously studied temperate and subarctic freely meandering rivers although not as pronounced and with a tendency to favour tighter curvature. From 1962 to 2010 the Aguapei River has undergone a significant reduction in sinuosity, a shift from tightly curving to more open bends, an overall decline in channel migration rates, an associated decrease in the frequency of neck-cutoffs and an overall increase in channel width. As the majority of the drainage basin (96%) was already deforested in 1962, channel form and process changes were, unlike an interpretation for an adjacent river system, not attributed to altered land-use but rather to a sharp ENSO-driven increase in the magnitude of peak flow-discharges of some 32% since 1972. In summary, this research revealed that recent climate and associated flow regime changes are having a pronounced effect on river channel behaviour in the Aguapei River investigated here. Copyright (c) 2018 John Wiley \& Sons, Ltd. (AU)

• FAPESP's process: 13/04284-3 - Aguapeí River morphodynamics: processes and resulting forms
• Grantee: Tainá Medeiros Suizu
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 14/02298-0 - The processes recorded in shapes: the morphodynamic of Aguapeí River unveiled in the meander evolution
• Grantee: Tainá Medeiros Suizu
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree