<![CDATA[Rapid population growth in the Tembung Area, Percut Sei Tuan District, has accelerated land conversion and increased exposure to flood hazards, creating a need for more objective approaches to residential site selection. However, existing housing selection practices remain largely subjective and have not sufficiently integrated flood-related spatial criteria within a GIS-based decision framework. This study addresses this gap by developing a Geographic Information System (GIS)-based Decision Support System (DSS) that integrates the Analytical Hierarchy Process (AHP) to support the prioritization of flood-safe residential locations. A quantitative approach was employed by combining expert judgments from the North Sumatra Housing and Settlement Department with geospatial data from DEMNAS, RBI, and BMKG. Four environmental criteria—elevation, distance to river, slope, and rainfall—were evaluated across three housing alternatives using a web-based platform developed with PHP and Leaflet.js. The AHP results identified elevation as the most influential criterion (46.58%), followed by distance to river (29.44%), slope (16.03%), and rainfall (7.95%). The Consistency Ratio (CR) of 0.0491 (CR < 0.10) indicates an acceptable level of consistency in the expert judgments. The final synthesis ranked Citra Graha Housing as the highest-priority alternative, with a score of 0.3989 (39.89%), followed by Benhil Indah (0.3163) and Mutiara Biru (0.2850). Black Box Testing achieved 100% functional conformity, demonstrating that the developed system successfully performed its specified functions. The main contribution of this study is the integration of AHP-based multi-criteria decision analysis with GIS-based spatial information to provide a more structured and transparent framework for flood-safe residential prioritization.]]>
