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Evaluation of Land Suitability for Crab Culture: A Methodological Study using GIS
Khulna region has around 104,624 hectares of shrimp farm in production (DOF, 1994-95). Additionally, there is one principal research and shrimp fry and 72 fish seed production centres at Government level and 12 shrimp fry production centres in the private sector. Likewise, there are 272 fish seed centres in the area in private hand. However, despite this actual aquaculture development, there is a lack of crab seed production centre in the region. The most common culture systems have minimum management, hence are considered to be a subsistence activity (Khan and Hossain,1996).  Figure 1. Location of the study area in Bangladesh and World context The GIS software used in this study was IDRISI for Windows version 2.0, a raster based GIS, developed at Clark University, USA. TOSCA digitising system (Version 2.03), DIGI-EDIT (Version 1.050) and CalComp Drawing Board III were used to digitise and edit vector layers. The software operated on a Pentium Pro 200 MHz processor with 128Mb RAM, 10 Gb hard disk. Display was via an iiyama Vision MasterTM 21? colour monitor using a Matrox Millennium 8Gb video card. Remotely sensed data sources The primary data sources for this study were two adjacent Landsat TM satellite images containing three multispectral bands (2, 3 and 4), acquired on 9 and 16 February 1996. A cloud free area of (column 3676 by 4915 rows) 18067,540 pixels was subset from the original two full scene image using WINDOW module of IDRISI for windows (version 2.0). This sub-scene image was geometrically rectified to the BANGTM46 grid co-ordinate system using 140 reference points on the 1:50,000 scale map. The rectification was achieved at an accuracy of 12.26 m. Thematic maps Data were extracted from a range of sources. Soil texture and soil pH were extracted from soil reconnaissance survey maps prepared by the Soil Resources Development Institute (SRDI) during the period of 1972 to 1975. Land use, flood, storm surge and drought were taken from SRDI maps of 1997. Soil and water salinity was taken from SRDI soil salinity report 1997 and Surface Water Modelling Centre (SWMC) report 1996. Roads, railways, rivers, international boundary and other topographical information were taken from topographical maps produced by Survey Bangladesh, scale 1:50,000, prepared during 1972 and 1979. Population density, literacy, agricultural by-product, animal wastes were taken from Bangladesh Bureau of Statistics (BBS) 1996 and BBS pocket dictionary 1996. Other data were taken from different sources such as atlas, journals, periodicals and published papers. |