Generation of Flood Hazard Maps in Marikina City Using GIS-MCDA Interval Rough AHP (IR’AHP)

Flood is a natural disaster mostly caused by typhoons that deal with health, property, and economic damages to areas affected by the inundation, especially on low lying areas such as Marikina, like in the times of typhoon Ondoy and typhoon Ullyses. This study aims to develop an accurate flood hazard map with the use of interval rough numbers to improve the urban management and flood response of the local government. The methodology considered elevation, Slope, distance from water surfaces, drainage density, land use/land cover, and soil profile as factors that would be relevant to the flooding of Marikina city. Online surveys were distributed to different experts under the scene of urban planning, hydrology, environmental protection, water supply and sanitation, and transportation to rate each individual factor’s importance with regards to the other factors by using the Saaty rating scale. Interval rough numbers, fuzzy, and crisp AHP were applied to the matrices of the experts’ rating of the factors and integrated with the generated flood hazard map. The generation of flood hazard maps was done with ArcGIS by utilizing different spatial maps gathered from online sites. After integrating the different MCDA techniques, a comparison was done to identify the most accurate on all the techniques and validation was done through utilizing historical flood data of Marikina City. After the application of the different MCDA techniques to the produced flood hazard map and validation by utilizing flood points of Marikina, the Rough Interval AHP proved to be the most consistent out of the two methods with an accuracy of 95.82%, 90.23%, and 80.72%, respectively. The results showed that from the total area of Marikina City, 33.16% out of it is under the classification of “very high” hazard, 24.42% is under the “high” hazard category, 17.67% is under the “moderate” hazard, 13.20% is under the “low” hazard, and 11.55% is under the “very low” hazard.