Seasonal inundation patterns in two large savanna floodplains of South America: the Llanos de Moxos (Bolivia) and the Llanos del Orinoco (Venezuela and Colombia)

Abstract

Abstract:Inundation patterns in two of the largest savanna floodplains of South America were studied by analysis of the 37-GHz polarization difference observed by the Scanning Multichannel Microwave Radiometer (Nimbus-7 satellite). Flooded area was estimated at monthly intervals for January 1979 through to August 1987 using mixing models that account for the major landscape units with distinctive microwave emission characteristics. Results are presented separately for five subregions in each of the two floodplain regions to show the spatial as well as temporal variability in inundation patterns. The total area inundated during the 9 years varied between 2069 and 78 460 km 2 in the Llanos de Moxos (also spelled as Mojos; median area, 23 383 km 2 ) and 1278 and 105 454 km 2 in the Llanos del Orinoco (median, 25 374 km 2 ), not including the open-water area of permanent lakes and river channels. The correlation between flooded area and river stage was used to extend the inundation records over a 30-year period in the Moxos (1967-97) and a 58-year period in the Orinoco. Interannual variability in inundation is greater in the Moxos than the Orinoco. Comparison of these data, however, with a previously published analysis of the Pantanal wetland shows that inundation patterns in these two floodplain regions are not as variable across years as they are in the Pantanal.

Surface Freshwater Storage Variations in the Orinoco Floodplains Using Multi-Satellite Observations

“…Our results agreed well with previous field observations [33] and with the 37-GHz polarization difference observed by the Scanning Multichannel Microwave Radiometer (SMMR) on the Nimbus-7 satellite [21,22]. The large and permanent open water areas (with constant annual inundation extent) corresponded with Maracaibo lake (the largest lake in South America, with an area of 13,210 km 2 , centered at 71.56°W and 9.82°N, just outside the boundary of the Orinoco Basin) and Gui reservoir (one of the largest artificial reservoirs in the world, with an area of 4250 km 2 , constructed on the Caroni River, centered at 63°W and 7°N).…”

“…In South America, previous studies using remotely-sensed observations have mainly provided a multi-year monitoring of changes in extent (e.g., [20][21][22][23][24][25][26]) and storage (e.g., [27][28][29]) at the basin-scale. In this study, we analyzed changes in inundation extent and water storage in the floodplains of the Orinoco Basin using multi-satellite observations.…”

Patterns and drivers for wetland connections in the Prairie Pothole Region, United States

“…These findings are particularly relevant to floodplains, permafrost landscapes and formerly glaciated landscapes that often exhibit low topographic gradients, low rates of infiltration, and low stream density. Runoff events in these landscapes rarely satisfy the threshold surface storage volume so that excess surface water (precipitation inputs exceeding soil infiltration and evapotranspiration) tends to accumulate instead of leaving the watershed as stream discharge (Hamilton et al 2004;Yao et al 2007;Aragón et al 2011;Kuppel et al 2015), leading to wetland consolidation and surfacewater connections.…”

Floodplain fish communities in river systems in Bolivia: Current knowledge and addressing future research challenges

“…The central plain of the Bolivian Amazon encompasses the fringing floodplain of the Mamoré River or Llanos de Moxos (Hamilton et al 2004, Duponchelle et al 2007. This is one of the largest floodplain systems of the Amazon and is characterized by gallery forests, abundant floodplain lakes and outlying savannahs that appear to be subject to backwater effects of the Mamoré.…”

“…The hydrological processes are well known and described in numerous studies (e.g. Hamilton et al 2004, Pouilly et al 2004a, Bourrel et al 2009). Floodplain waterbodies are closely associated with the hydrological dynamics; some of which dry out as the flood ebbs and others form large floodplain lakes for most of the year.…”