Ghana sub-model Case Study - Institute of Aquaculture - University ...

aqua.stir.ac.uk
  • No tags were found...

Ghana sub-model Case Study - Institute of Aquaculture - University ...

GIS for AquacultureProfessor Lindsay G RossUOS/WRI/Royal Society/Leverhulme WorkshopAccra, Ghana. 2013.Case Study 2:A spatial plan for small-scaleaquaculture in GhanaProfessor Lindsay RossInstitute of AquacultureUniversity of Stirling, Scotlandhttp://www.aqua.stir.ac.uk/GISAP/ObjectiveConstruct GIS models to show suitable areasNo single solution : No single methodCan be based on sub-modelsMulti Criteria Evaluation is very importantReclassification is very importantWeighting is very important5. Case Study 2 - Ghana 1


GIS for AquacultureProfessor Lindsay G RossSub-Models:Water availabilityWater qualitySoil propertiesInputsMarketsInfrastructureConstraintsSub-model 1.Water availability: Obviously water is vital for development ofaquaculture Sources:• Rain• Small rivers and streams• Major Rivers• Lakes• Irrigation systems• Underground water5. Case Study 2 - Ghana 2


GIS for AquacultureProfessor Lindsay G RossStructure of the sub-model:rainevaporationVoltaSystembalancelakeupperVoltaIrrigationschemesminor rivers& streamsMCE - constraintsResultWater Balance:rainfall – (evaporation + seepage) = net water balance5. Case Study 2 - Ghana 3


GIS for AquacultureProfessor Lindsay G RossSmall rivers and streams:minor rivers + 1.0kmLakes:Lake Volta + 2km5. Case Study 2 - Ghana 4


GIS for AquacultureProfessor Lindsay G RossIrrigation systems:current irrigation systems + 1kmIrrigation:current systems + 1km5. Case Study 2 - Ghana 5


GIS for AquacultureProfessor Lindsay G RossHow to combine these factors? First: Reclassify all factors in terms ofsuitability for aquaculture Second: Assign a weighting to each factor Finally: Run a weighted overlay (Multi-Criteria Evaluation)Reclassification: Based on a common 5 point scale, where:• 0 = Background• 1 = Very poor• 2 = Poor• 3 = Satisfactory• 4 = Good• 5 = Excellent5. Case Study 2 - Ghana 6


GIS for AquacultureProfessor Lindsay G RossSome Constraints: Wildlife reserves Forest reserves Lakes and Rivers (for pond construction) Military areas Cities and towns Roads and other infrastructureConstraints – Boolean:5. Case Study 2 - Ghana 9


GIS for AquacultureProfessor Lindsay G RossConstraints – Boolean:Can create a singletotal constraint imageby using OVERLAYwith multiplicationOr, in IDRISI, a list ofconstraint images canbe offered to the MCEmoduleEnhanced result:SCALAR operationapplied to the layersbefore running MCE [x 5]Produces a scale of1 to 25Sensitivity enhancedWith application ofconstraints5. Case Study 2 - Ghana 10


GIS for AquacultureProfessor Lindsay G RossTo complete the model: There are at least 5 other sub-models todevelop• In terms of aquaculture• In terms of each species Finally need to combine the results of thesesub-models• As a decision tree ?• As a Multi Criteria Evaluation?5. Case Study 2 - Ghana 11

More magazines by this user
Similar magazines