Locating Areas Prone to Flood Spreading using the Weighted Linear Composition Method in the Watershed of Baghan Dam in Bushehr

Flood spreading is one of the suitable methods for controlling and optimal use of flood in arid and semi-arid regions, and consequently, locating areas prone to flood spreading is very important. The purpose of this study is to locate areas prone to flood spreading in the Baghan Dam watershed of Jam city located in Bushehr province.

For this purpose, effective layers including slope, land use, geology, geomorphology and fault as standard options for physical properties, permeability layers and alluvial thickness as standard options for hydrological properties and distance from wells, aqueducts, City, village, and road were considered as options for the criteria of economic and social characteristics, as digital information layers, and were standardized by fuzzy logic. In the next stage, slope, land use, geology and geomorphology layers were standardized as Boolean logic as constraints. Based on the average of experts' opinions, the layers were weighted by hierarchical analysis (AHP) and the incompatibility rate (0.09) was calculated. The layers were combined by multivariate spatial evaluation (SMCE) and weighted linear composition (WLC) techniques and final maps of susceptible areas were prepared.

The results of hierarchical analysis (AHP) showed that the distance from the fault with a weight of 0.238 had the highest and the distance from the well with a weight of 0.005 had the lowest value in locating the flood spread in the watershed of Baghan dam. The incompatibility rate was calculated to be 0.09. Based on the results of combining the criteria by Terrset software, Baghan dam watershed into 5 areas unsuitable (88%), poor (0.10%), moderate (1.6%), good (5%) and very good (3.5%) (Figure 14) was divided.

Overall, the results showed that 88% of this area has poor capability, 0.1% has poor capability, 1.6% has moderate capability, 5% has good capability and 3.5% has very good capability for flood spreading. The final map with the current situation of the area was evaluated by 30 points. The evaluation results showed that there is no significant difference between the final map and the condition of the arena.