The potential of geographical information system-based modelling for aquaculture development and management in South Western Bangladesh
This study describes the delineation of appropriate sites for aquaculture using remote sensing, GPS and GIS. A 1996 composite Landsat TM image covering the south-western part of Bangladesh was used to identify water bodies, the extent of brackish water and associated land use features in the image. The Remote Sensing image was complemented by digitised secondary data from a range of sources, including hard copy maps to produce a GIS database which included environmental layers such as water bodies, rivers, soils, land use, temperature, rainfall, salinity and pH. The database also included infrastructural issues, such as roads, railways, processing plants, towns and cities. A series of GIS models were developed in order to identify and prioritise the most suitable areas for freshwater prawn, tilapia and carp and brackish water shrimp and crab farming. A range of scenarios for land allocations were used to develop a series of resource use models linked to likely production outcomes. Global warming and accelerated sea level rise is considered in the study area with different sea level rise scenarios of 50, 100, 150 and 200cm. The consequence of land losses and displacement of the population from the area in different situations is discussed. The economic characteristics of shrimp farming and alternative land uses in the Khulna region were also considered. Five land use options were studied based on economic output and job potential. Among these, brackish water shrimp and crab culture, moderately saline tolerant tilapia and prawn culture, fresh water carp culture and traditional rice production systems, and fresh water prawn culture performed best followed by brackish water shrimp and crab culture. This study showed the extent of potential for aquaculture in the Khulna region and further demonstrates the usefulness of GIS as an aquaculture-planning tool. Model programming was also found to be very useful tool to enabling regenerating of multiple scenarios very quickly. Overall, GIS modelling associated with remote sensing has great potential for informed decision-making in aquatic production systems and optimising management of natural resources in a region where they are already under considerable pressure. The implications for use of these systems in reducing land use conflict and sector planning for the region are discussed.