Geoinformation, monitoring and assessment Environment

Posted July 1999

Inventory and monitoring of shrimp farms in Sri Lanka by ERS-SAR data

by C. Travaglia, J.M. Kapetsky and G. Profeti
34 pp, 24 figures, 11 tables
Environment and Natural Resources Working Paper No.1
FAO, Rome, 1999

Full publication now available on-line


Shrimp farms map of the Seguwantiyu test site

Inventory and monitoring of shrimp farms are essential tools for decision-making on aquaculture development, including regulatory laws, environmental protection and revenue collection. In the context of government aquaculture development policy, much attention has to be focused on the identification and monitoring of the expansion of shrimp farms. Therefore, the availability of an accurate, fast and mainly objective methodology that also allows the observation of remote areas assumes a great value. The satellite remote sensing approach is also economically viable, as the value of shrimps more than justifies an accurate inventory and monitoring of the development of the farms.

SAR data are unique for mapping shrimp farms, not only for their inherent all-weather capabilities, very important as shrimp farms occur in tropical and sub-tropical areas, but mainly because the backscatter from surrounding dykes allows for recognition and separation of shrimp ponds from all other water-covered surfaces.

The study is based on interpretation of SAR satellite data and a detailed image analysis procedure is described. Although hardware and software needed for the extraction of useful information from SAR data are currently available at most remote sensing laboratories, good knowledge in imaging radar theory and practice in handling and processing SAR data are not. The report aims at the necessary technology transfer for an operational use of the approach indicated in other similar environments.

The methodology reported in this study has been tested under operative conditions in north-western Sri Lanka with the support of FAO project TCP/SRL/6712. The mapping accuracy achieved for shrimp farms, after field verification of preliminary results and refining of interpretation keys, is estimated to be more than 90 percent.

Keywords: aquaculture, mapping shrimp farms, remote sensing, Sri Lanka, synthetic aperture radar

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