Updated December 1998
by C. Travaglia and H. Macintosh
36 pp, 13 figures, 7 tables
RSC Series No. 69, FAO, Rome 1996
Wetlands are a dynamic environment being affected both seasonally and annually by variable climatic conditions. Their surface area, often encompassing tens of thousands of square kilometres, is consequently subject to large variations. Monitoring wetland surface area fluctuations by traditional means is often difficult, time consuming and economically prohibitive.
Satellite remote sensing can provide baseline data at frequent intervals. The thermal inertia approach through NOAA AVHRR LAC data provides, at a low cost, a quite accurate assessment of the inundated areas, often covered with floating or water-rooted vegetation, but is limited by weather conditions, being applicable only to cloudless situations; ERS-SAR data provide very accurate information on all features of the wetland system, without weather restrictions. The two formats can work well together, providing different but complementary information.
NOAA AVHRR data should be used whenever clear sky conditions occur, mainly during the dry season. ERS-SAR data should be considered, as an alternative, when cloudy sky conditions are prevailing during the wet season, to provide essential data on wetland's expansion; moreover, they should be selected over limited areas crucial for assessing swamp fluctuations, for obvious economical reasons.
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