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Abstract: Assessing Dredging Impacts on West African Wetlands with Remote Sensing and Geographic Information Systems

Ade Sobande Associates, Gahanna, OH

Environmental impacts of dredging on producing oil fields within a West African wetland region were assessed using remote sensing and geographic information systems. Two sets of imagery, recent RadarSat, and old LandsatTM were utilized to document changes through time. The Landsat provided important pre/early production information but was limited in applicability due to the haze, dust and cloud cover typifying the region. The RadarSat was relatively unaffected by poor atmospheric conditions and it's ability to "detect water absolutely" especially useful. Consistent patterns of interpretation were applied across both set of imageries and focused on identifying the major ecological zones as well as mapping flooding, hydrologic processes and sediment transport. The basis for a stochastic evaluation was hence established. A field program comprising a baseline sampling and ground truthing was also carried out, and data on field conditions as soil, water and vegetation obtained.

All data was integrated on a GIS platform facilitating an efficient comparative analysis of the imageries and interpretations, and making the extensive field tabular, text and raster data more accessible and spatially relevant. Inferences for dredging impacts are presented and limitations discussed.

AAPG Search and Discovery Article #90930©1998 AAPG Eastern Section, Columbus, Ohio