Geoinformation, monitoring and assessment Environment

Updated December 1998

Remote Sensing Centre Series

Monitoring wetlands for fisheries by NOAA AVHRR LAC thermal data

By C. Travaglia, J. Kapetsky and Mrs. G. Righini
30 pp, 12 figures, 6 tables
RSC Series No. 68, FAO, Rome 1995.


Summary

Wetlands are economically important and sensitive ecosystems usually covering extensive areas, but subject to large variations, both seasonally and inter-annually, according to the climatic conditions of the region involved. The fishery potential of wetlands is directly related to the duration and extent of the floods, as well as to the efficiency of fishing. Consequently, fishery potential varies from season to season and from year to year. Frequent baseline data on wetlands are essential for assessing fishery potential and for an host of hydrologic and environmental applications.

Remote sensing is the only tool which can be used to provide those data at frequent intervals and economically; thus an operative methodology based on the thermal inertia difference between dry and wet lands has been developed from NOAA AVHRR LAC thermal data (channel 4) complemented by NDVI studies.

The rationale of the methodology is that water and aquatic vegetation have a higher thermal inertia than that of dry land around and of non-aquatic vegetation, that is they warm-up less during the day. This permits mapping from NOAA AVHRR LAC thermal data at 1: 1,000,000 scale with good accuracy.

Wetlands in Zambia and Sudan have been monitored through a selective time series of data. Results are in line with available ground estimations and show the great time variability of those areas.


The above publication is available from:
Chief, FAO/SDRN
Viale delle Terme di Caracalla
00100 Rome, Italy
(e-mail: changchui.he@fao.org)



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