As climate change intensifies and extreme weather events become more frequent, extreme rainfall presents significant challenges to both human society and the natural environment. This paper develops a county level risk assessment system using the Hazard-Exposure-Vulnerability-Adaptation (H-E-V-A) framework, incorporating economic, personal, and public aspects. Utilizing Geographic Information System (GIS) processing, the study generates grids (200 m × 200 m) for the Exposure Index (EI), Vulnerability Index (VI), Adaptation Index (AI), and integrated Risk Index (RI). This assessment focuses on the extreme rainfall event in the upstream region of the Dawen River in Laiwu on August 10, 2019. The study evaluates the integrated flood risk in the area and verifies the accuracy of the assessment system. Findings indicate that EI is highest in densely populated areas like Fengcheng and Pengquan. Rural areas exhibit higher VI due to severe population aging, while the central urban area demonstrates stronger building resilience with a higher AI. The integrated risk for Typhoon Lekima in 2019 identifies Kouzhen, Gaozhuang, Lixin, Niuquan, and Fengcheng as high-risk areas. The vector map indicated that high-risk areas were near river channels and low-lying villages with a high degree of population aging. The result can assist policymakers in formulating disaster reduction strategies and serve as a reference for selecting regions to build 1D-2D hydrodynamic models.