TY - JOUR
T1 - Using geomorphic understanding of catchment-scale process relationships to support the management of river futures
T2 - Macaé Basin, Brazil
AU - Marçal, Mônica
AU - Brierley, Gary
AU - Lima, Raphael
PY - 2017/7/1
Y1 - 2017/7/1
N2 - Impacts of colonial settlement upon catchment-scale fluvial geomorphic relationships are reported for a relatively small catchment in northern Rio de Janeiro State, Brazil. Structural controls have induced the type and patterns of rivers in Macaé Basin. Fault block activity has resulted in steep, incised headwater streams above the escarpment. Confined and partly confined rivers in mid-catchment reaches of the rounded foothills have limited potential for geomorphic adjustment. Fluvial, estuarine and marine sediments in low relief landscapes of the lowland plain have supported the development of meandering sand bed rivers, with many cut-and-fill (intact valley fill) deposits in tributary systems. Indigenous people exerted relatively minor, localized impacts upon the geomorphology of this river system. Portuguese settlement since the sixteenth century brought about clearance of much of the Atlantic Forest of lowland reaches, and subsequent establishment of sugar cane and coffee plantations. Lowland reaches were channelized from the 1940s-1980s for flood protection and to support the expansion of pastoral agriculture. Significant adjustments have occurred to these geomorphologically sensitive reaches. In contrast, although rivers in the rounded foothills were impacted by forest clearance, the limited availability of sediment stores along these reaches has limited the extent of geomorphic responses to human disturbance. Relatively inaccessible upland reaches were even less impacted, and are now major conservation areas. Building on principles of the River Styles framework, catchment-scale evolutionary trajectories of rivers in the Macaé Basin are assessed based on analysis of patterns of river types, their capacity for adjustment and connectivity relationships, and responses to disturbance events. From this, three future scenarios of prospective evolutionary traits are developed: a ‘steady as she goes’ scenario, an optimistic (effective, proactive management) scenario, and a ‘doomsday’ scenario.
AB - Impacts of colonial settlement upon catchment-scale fluvial geomorphic relationships are reported for a relatively small catchment in northern Rio de Janeiro State, Brazil. Structural controls have induced the type and patterns of rivers in Macaé Basin. Fault block activity has resulted in steep, incised headwater streams above the escarpment. Confined and partly confined rivers in mid-catchment reaches of the rounded foothills have limited potential for geomorphic adjustment. Fluvial, estuarine and marine sediments in low relief landscapes of the lowland plain have supported the development of meandering sand bed rivers, with many cut-and-fill (intact valley fill) deposits in tributary systems. Indigenous people exerted relatively minor, localized impacts upon the geomorphology of this river system. Portuguese settlement since the sixteenth century brought about clearance of much of the Atlantic Forest of lowland reaches, and subsequent establishment of sugar cane and coffee plantations. Lowland reaches were channelized from the 1940s-1980s for flood protection and to support the expansion of pastoral agriculture. Significant adjustments have occurred to these geomorphologically sensitive reaches. In contrast, although rivers in the rounded foothills were impacted by forest clearance, the limited availability of sediment stores along these reaches has limited the extent of geomorphic responses to human disturbance. Relatively inaccessible upland reaches were even less impacted, and are now major conservation areas. Building on principles of the River Styles framework, catchment-scale evolutionary trajectories of rivers in the Macaé Basin are assessed based on analysis of patterns of river types, their capacity for adjustment and connectivity relationships, and responses to disturbance events. From this, three future scenarios of prospective evolutionary traits are developed: a ‘steady as she goes’ scenario, an optimistic (effective, proactive management) scenario, and a ‘doomsday’ scenario.
KW - channel adjustment
KW - future scenarios
KW - land use
KW - landscape connectivity
KW - landscape evolution
KW - river diversity
UR - http://www.scopus.com/inward/record.url?scp=85018771709&partnerID=8YFLogxK
U2 - 10.1016/j.apgeog.2017.04.008
DO - 10.1016/j.apgeog.2017.04.008
M3 - Article
AN - SCOPUS:85018771709
SN - 0143-6228
VL - 84
SP - 23
EP - 41
JO - Applied Geography
JF - Applied Geography
ER -