Estimation of the weighted scores. The objective of this research is to map flood hazard zones in Najran city. The decision factors to relate attributes to suitability concerning a particular goal are the factors controlling flood hazard in the study area. The primary decision factors
are considered in this study as listed in section 3 (see Fig. 5). Once the decision factors are identified and selected, sub-factors are identified to better describe these criteria. For example, the surface slope is sub-divided into 7 sub-factors) and (We used AHP, which is a multi-criteriadecision-making approach introduced by Saaty (1977) and Saaty (1994). The AHP is a decision support tool, which is used to solve complex decision problems. It uses a multilevel hierarchical structure of objectives, criteria, sub criteria, and alternatives. Three levels are used in our problem: goal, factors criteria and spatial attributes. Each land use has a different surface roughness value. These values (ranged from 0.03 to 0.1) were specified for different land use (see Table 6).