This study delves into the flood dynamics of the Jiayu River's small watershed in Zhengzhou's mountainous region during the July 20 rainstorm. It explores the spatiotemporal impacts of landscape features on flood inundation depth intensity, and offers strategic suggestions to bolster flood resilience in Henan province's mountainous area, thereby easing socio-economic and ecological issues. Utilizing Gaofen-6 remote sensing data, Advance Land Observing Satellite(ALOS)-PALSAR surface elevation data, and hourly rainfall figures, we constructed a two-dimensional hydrological model of the Jiayu River Basin via the MIKE 21 hydrodynamic model. This allowed us to analyze flood inundation depth and area across the river's upper, middle, and lower sections on July 20, 2021. With the aid of the bivariate spatial autocorrelation model, we examined the spatiotemporal correlation variations between flood inundation depth intensity and landscape composition and topographic factors. Our findings reveal that (1) the submerged area of the Jiayu River Basin swiftly expanded from 0:00 to 6:00, reaching its peak at 9.59 km² at 18:00. Here, the submerged area percentages were 18.88% in the lower reaches, 8.25% in the upper reaches, 12.03% in the middle reaches, and 36.11% in areas with over 3 m submersion depth. (2) Topographic elements (mean Moran's I=0.159) exhibited a more significant influence on flood inundation depth intensity than land type (mean Moran's I=0.096), with the main drivers being Relative Elevation (RE), Topographic Wetness Index (TWI), percentage of mining pits area, percentage area of water bodies, percentage area of construction land, percentage area of crop land, percentage area of forest land, and percentage area of grass land. Their correlation with flood inundation depth intensity peaked between 18:00 to 24:00. (3) Multiple factors' combination amplified the influence of landscape features on flood inundation depth intensity. In the upstream, mining pits and relative elevation were the dominant drivers, while water bodies and TWI were key in the midstream and downstream. (4) The "high-high" and "high-low" areas between the average flood intensity and the landscape characteristic index, comprising approximately 0.47% to 9.85%, were primarily located in the central mountainous area of the upper reaches and surrounding the northern river channel, along the river channel in the middle and lower reaches, and around the Changzhuang reservoir. We recommend transforming the upstream open mine into a reservoir, enhancing vegetation, improving the riparian green space in the middle and lower reaches, boosting the green infrastructure in downstream urban areas, and minimizing urban flood risk by improving connectivity to the river.