International Journal of information Systems and Informatics e-ISSN 2746-1378 Vol. 2, No.4 December 2021 18 Published by: GIS-based Flood Risk Assessment in the Urban Catchment of Uyo Metropolis, Nigeria Nsiegbe, Dickson Kinikawo, Weli, Vincent E, Chukwu-Okeah, Gift O., & Eludoyin, Olatunde S. Department Of Geography And Environmental Management University Of Port Harcourt, Nigeria Emails: Dicksonnsiegbe@Gmail.Com Abstract Flood occurs as a result of rising global temperatures, more precipitation, increased runoff, and an increase in the rate of urban flooding. The goal of this research is to calculate the flood risk assessment of a selected urban catchment in the Nigerian metropolis of Uyo. Secondary data were obtained from Landsat images of the study area using a correlational research design. Using supervised categorization of landuse in the area, the watershed pattern, landuse/landcover, and inundation level were determined using the area's Digital Elevation Model. The study also used a GIS-assisted computer simulation of storm water created by enhanced DEM to assess storm water level and inundation as a function of landuse/landcover change. Storm water generation assessment, inundation modeling, assessment of land cover and level of inundation, and evaluation of flash flood susceptibility using modeled inundation were among the hydrological models and techniques used to analyze the data. The findings revealed that Uyo has a number of streams with varying flow lengths. Uyo has 21 sub-basins, according to the study. In uyo, the total runoff was greater (0.74) inches. In Uyo, the rate of change in catchment behavior, such as catchment precipitation, node flooding, and runoff, increased with the time of day, whereas the rate of change in runoff volume varied somewhat. The hydrograph was not wider because the sections of Uyo metropolitan that were prone to moderate and high floods were higher (78.03 percent ). Based on these findings, the study suggests that better city design is needed to control the impact of flooding in the study area. To prevent the loss of life and property, areas prone to moderate and high flood vulnerability should be closely monitored and secured. Keywords: Catchment, Flood, Urban, Vulnerability 1. Introduction The rate of urban flash floods is increasing as global temperatures rise, seasonal shifts occur, and precipitation levels rise, resulting in increased run-off (Sunnin, Saro, Moung-Jin and Hung- Sup, 2018). Heavy rains, typhoons, floods, and other weather events disrupt the hydrological system, putting more strain on drainage systems, water treatment plants, and sewage treatment plants in metropolitan areas (Muneerudeen, 2017). As a result of the high amounts of rainwater in rivers, the risk of flooding increases significantly. A flash flood is defined as a flood that occurs suddenly, lasts only a few minutes, and has a reasonably high peak discharge (Ismail, 2015). Flash floods happen quickly, usually within an hour of rainfall, and are often accompanied by landslides, mud flows, bridge collapse, and property damage (Hapuarachichi, Wang & Pagano, 2019). In recent years, floods have been predicted using hydrologic and hydraulic models, which required large-scale data that was not available. Before 2000, according to Aneesha, Shashi, and Meshapam (2019), the use of Geographic Information System (GIS)-based methods for flood risk and hazard evaluation was uncommon. As a result, it is critical for municipal and urban planning specialists to identify and manage the natural risk posed by flash floods in order to plan for the future. With the advancement of computer technology, disaster management and mitigation authorities can now accurately predict where floods will occur and how severe they will be. Many studies have been done in the past and recently to map floods in many nations in order to estimate the amount of flash flood and inundation in order to make flood hydrographs