The Physical Dynamics of the River–Lake Floodplain System

EDMUNDO C. DRAGO

The Middle Paraná River: Limnology of a Subtropical Wetland

Springer-Verlag

Lugar: Berlin; Año: 2007; p. 83 - 122

The Paraná River is the second largest river in South America in terms of catchment area (1.51 million km2), the second longest (4,400 km from the headwaters of Grande River in Brazil to the Río de la Plata estuary), and the third in terms of discharge (about 470 km3 of freshwater carried to the seaannually). Within this fluvial hydrosystem, the segment of the Middle Paraná encompasses 700 km upstream from the Paraguay outlet to the apex of the delta upstream from Rosario city (Entre Ríos Province, Argentina) (Chap. 1,Fig.1.5). Along its main channel, the Middle Paraná has built a relatively wide fringing floodplain with a surface of ca. 20,000 km2. This floodplain resembles other large tropical and temperate floodplains in its amplitude and duration of flooding, and in many of its ecological characteristics. The annual phases of flood and drought and the complex hydrological connectivity between lotic and lentic waters are the major variables driving the lateral and longitudinal exchanges of sediments, organic matter and organisms at the riverscape scale. Moreover, the hydrology of the floodplain lakes, as well as the sedimentation-resuspension processes, the thermal behavior and the heat content variations are closely linked with the flood and drought phases. The aim of this chapter is to extend the knowledge on the hydro-sedimentological dynamics, as well as the thermal structures and mixing processes that occuring the river–floodplain lake systems of the Middle Paraná during the annual connection and disconnection phases.