@Article{CostaNiemNovoAher:2002:BiPrMa,
author = "Costa, Maycira Pereira de Farias and Niemann, O. and Novo, Evlyn
M{\'a}rcia Le{\~a}o de Moraes and Ahern, F",
title = "Biophysical properties and mapping of aquatic vegetation during
the hydrological cycle of the Amazon floodplain using JERS-1 and
Radarsat",
journal = "International Journal of Remote Sensing",
year = "2002",
volume = "23",
number = "7",
pages = "1401--1426",
month = "Apr.",
keywords = "ESTUDOS INTEGRADOS DO MEIO AMBIENTE, Amaz{\^o}nia (Regi{\~a}o),
plantas aqu{\'a}ticas, biomassa, ciclo hidrol{\'o}gico,
plan{\'{\i}}cies inundadas, imagens de radar,
classifica{\c{c}}{\~a}o de imagens, mapeamento, radar de
abertura sintetica, SAR, forestas, JERS 1, biomass, synthetic
aperture radar, forest, rice, canopy, aquatic plants, hydrological
cycle, food plains, radar imagery, image classification,
mapping.",
abstract = "Field measurements were combined with Synthetic Aperture Radar
(SAR)images to evaluate the use of radar for estimating biomass
changes and mapping of aquatic vegetation in the lower Amazon.
Field campaigns were conducted concomitant to the acquisition of
Radarsat and JERS-1 images at five different stages of the
hydrological cycle. The temporal variability of the SAR data for
aquatic vegetation shows a dynamic range of 5 dB, however this is
due dominantly to the significant differences (p<0.05)between the
low water season when vegetation is small and just emerging and
other seasons when vegetation is fully developed. The spatial
variability of the above-water biomass is detectable with radar
data. Significant correlation (p<0.05)exist between backscattering
coefficients and both above-water dry biomass and height of the
plants. The logarithmic relationship between backscattering
coefficients and biomass suggests that (1)at low biomass, high
transmissivity of the microwave radiation through the vegetation
canopy occurs and the backscattering is a result of quasi-specular
reflection of both C and L bands and a minor contribution of
canopy volume scattering from C band; (2)at intermediate levels of
biomass, moderate changes in backscattering values occur and the
saturation point of backscattering is reached; and (3)at high
biomass, the transmissivity of C and L band radiation is equally
attenuated and backscattering approaches similar values for both.
A combination of Radarsat and JERS-1 images from high and low
water periods were classified using a segmentation algorithm and
had an accuracy higher than 97 percent for vegetated areas of the
floodplain. Although further research is needed to better
understand the saturation points for Radarsat and JERS-1 data,
these findings clearly show that C and L bands can accurately map
aquatic vegetation of the Amazon floodplain.",
copyholder = "SID/SCD",
issn = "0143-1161",
label = "9556",
targetfile = "INPE 8579.pdf",
urlaccessdate = "21 maio 2024"
}