<p>Wetlands play a crucial role in biodiversity conservation. Biodiversity predictions should comprehensively consider the effects and interactions of the soil and the hydrological and topographical factors. However, existing studies have primarily focused on the individual effects of these factors on wetland biodiversity. In this study, we aimed to develop a model to investigate the effect of soil and the topographical and hydrological factors on key biodiversity indicators, namely the effective number of species and ratio of exotic and invasive species coverage, in riparian wetlands of the Han River in Korea. Field surveys at 30 sites provided data on species composition and the soil and the topographical and hydrological factors. Principal component analysis and multiple regression analysis enabled the identification of key environmental influences on biodiversity. The findings indicate that hydrological factors, especially water discharge and water level fluctuations, substantially influenced the effective number of species and invasive species prevalence. Increased water discharge was associated with a higher effective number of species and ratio of exotic species coverage and a lower ratio of invasive species coverage, whereas fluctuating water levels negatively impacted all biodiversity indicators. Soil factors such as clay content influenced the ratio of exotic species coverage, whereas topographical slope variance affected species diversity. Regression models demonstrated explanatory power for the effective number of species (<i>R</i>² = 0.43) and the ratio of invasive species coverage (<i>R</i>² = 0.29). These findings highlight the importance of hydrological and soil factors in influencing biodiversity, offering valuable insights for sustainable wetland management and biodiversity conservation strategies in riparian ecosystems.</p>