Anthropogenic changes in urbanised hydromorphological systems in a humid tropical environment: River Pinheiros, Sao Paulo, Brazil
da Luz, Rodolfo Alves; Rodrigues, Cleide
published: May 1, 2015
ArtNo. ESP023105902006, Price: 29.00 €
The urbanised meandering fluvial system of River Pinheiros in the humid tropical environment of Sao Paulo, Brazil, has undergone many hydromorphological changes over the past 100 years of urban development within one of the largest metropolitan conglomerations of the Americas. These changes can be explained by using such techniques as anthropic and historical geomorphology, geomorphological mapping, and geoindicators of change in landforms, materials and processes. Three 1:25,000 geomorphological maps of representative stages of intervention: the pre-disturbance map (representing the original system), the active disturbance map, and, the post-disturbance map were utilized to establish, measure and compare historical changes in the hydromorphological system since 1930. The results reveal the great magnitude and high efficiency of direct and indirect human interventions on fluvial landforms and hydromorphological processes. Changes that might be expected to occur at recurrence intervals of 1 in 103 to 1 in 104 years in natural conditions occur much more frequently (1 in 100 – 102 years) because of urbanisation. The pre-urban meandering channel was straightened, with the length being reduced by 45%, the width being increased by 185%, and the water flow becoming artificially controlled and reversed. The previous floodplain level was eliminated and new terrace levels were created by human activity, particularly by landfills, whose volume was estimated to be 16.28 × 106 m3. Understanding changes of this magnitude can assist in risk assessment, geotechnical studies, landscape rehabilitation and river management in urban areas.