A land evaluation model for irrigated crops using multi-criteria analysis.

This thesis investigated the optimal land suitability for irrigated crop production of barley and wheat in Benghazi region of Libya using multi-criteria analysis (MCA) of fuzzy logic and the Analytical Hierarchy Process (AHP). In the MCA, fourteen land suitability factors including twelve soil characteristics, topography and erosion hazard were evaluated. Local experts used their experience and assigned different weights based on crop requirements through pairwise comparison matrix. The combination of these methods was aimed at developing existing land evaluation model in the study area that was based on Boolean logic. Three models were developed based on Food and Agriculture Organization Framework: Model 1 was based on existing land evaluation model of Boolean and equal weights; Model 2 was based on Boolean but with difference in weights assigned using AHP; and Model 3 was based on Fuzzy and AHP. The results of these models were compared using crosstab classification (Kappa statistic and overall agreement). On comparison, Model 2 and Model 3 demonstrated higher agreement in spatial distribution of land suitability class than Model 1 for both barley and wheat crops. However, Model 3 is more realistic than the other two models when tested by linear regression. This implies that the application of fuzzy logic and AHP in MCA produces areas that are most suitable for barley and wheat production than would other methods. In practice, however, land management practices by farmers may lead to different yield in the selected suitable area. This thesis makes original contributions in the field of identifying the most suitable land evaluation model for application to crop production improvements. Furthermore, the results of this research will be useful to the Libyan authorities in planning for the optimisation of available land-use for strategic production of barley and wheat crops. This is pertinent to issues of food security. The approaches are transferable to other regions of the world which face similar challenges in domestic food production.