Application of GIS to Identify Potential Areas for Aquaculture in Badulla District in Uva Province

Abstract

Aquaculture is farming aquatic organisms including fish, mollusks, crustaceans and aquatic plants (FAO, 1990). The main intent of the present study is to highlight the role Geographic Information System (GIS) in identifying potential areas for aquaculture in Badulla district. The study was carried out in Badulla district in Sri Lanka by the geographical coordinates of longitude 80 .45 to 81 .15. Latitude 6 .34 to 7 .18. Data have been collected from secondary sources and used to generate maps to identify fresh water bodies in Badulla district. Map of seasonal tanks, reservoirs and tanks, stream network and rivers of Badulla district were developed. Water availability (proximity to rivers), soil texture, soil pH, rainfall, temperature and topography (slope, elevation) and land use factors were considered to identify potential areas for aquaculture (pond culture). Protected areas are considered as constraints. Water availability, soil texture, soil pH, slope, elevation, rainfall, temperature, land use/ land cover thematic layers were created using ArcGIS 10.1 software. All these thematic layers have been assigned the weights according to their relative influence on pond construction using Analytic Hierarchy Process (AHP) and GIS approach. Finally, all thematic layers have been integrated in a ArcGIS 10.1 environment to generate an aquaculture potential map. Thus, four aquaculture potential areas have been Identified, viz. “Most suitable”, “Suitable”, “Fairly suitable”, “Unsuitable”. The north part of the Badulla district is identified as most suitable and the southern part of the Badulla district is identified fairly and unsuitable for aquaculture in Badulla district.

Methodology

Data collection: Secondary data were collected from secondary sources.

GIS analysis: reservoirs and tanks, Rivers, Stream network of Badulla district were digitized using Arc View 3.1 software. GPS coordinates of seasonal tanks were stored & developed a map using ArcGIS 10.1 software to identify fresh water resources in Badulla district and all data were stored in ArcGIS 10.1 environment and factor thematic layers were generated to identify potential areas for aquaculture.

Analytic Hierarchy Process (AHP) - AHP is a multi-objective, multi criteria decision making approach that employs a pair wise comparison procedure to arrive at a scale of preference among a set of alternatives (Dai et al., 2001). Thematic layers were evaluated using scores and each weighted according to their relative importance on the aquaculture using Analytic Hierarchy Process (AHP) and GIS approach.

Map Generation -Each thematic layer was evaluated using the scores that were obtained according to the weighted linear combination in ArcGIS 10.1 environment. Vector format was converted to raster format. To reject the constraints the final result was multiplied by absolute constraints. The protected areas were allocated a zero score. Finally, the potential areas for aquaculture map was created and categorized into four levels: Most suitable, Suitable, Fairly suitable, Unsuitable based on the total scores obtained from the weighted linear combination.