Under the continuous influence of climate change and human activities, the attribution analysis and prediction of the temporal and spatial dynamics of water and sediment have become fundamental aspects of soil and water resources management and watershed governance. This paper focuses on the Tao River basin (TRB) and Zuli River basin (ZRB), situated in the Qinghai-Tibet Plateau and Loess Plateau, as the research area. Using the SWAT model and scenario simulations, the study identifies the drivers of changes in water and sediment processes and predicts future water and sediment dynamics. Model analysis of parameter sensitivity and its optimization revealed differences in influential mechanisms. River discharges in the TRB were affected remarkably by storage and regulation of the groundwater system, the sediment processes were more sensitive to parameters addressing river channel characteristics; while river discharges in the ZRB were deeply related with land surface infiltration, the sediment processes there were influenced more by underlying conditions. the direct effects of driving factors on basin water and soil processes were generally higher than the indirect ones. Runoff changes in both basins were primarily influenced by precipitation, with vegetation having a more significant impact on runoff in the ZRB. In the TRB, sedimentation processes were mainly driven by precipitation, while in the Zuli River Basin, runoff exerted a more pronounced driving effect. Precipitation plays a controlling role in the spatial distribution of water and sediment, with factors such as topography, soil type, and land use/cover moderating these processes. Predictive analyses indicate that under a low-emission scenario, both runoff and sediment in the watershed associated with the two development models are projected to decline. Conversely, under medium and high-emission scenarios, both runoff and sediment are expected to increase. The runoff and sediment processes are closely tied to future climate change, and changes in underlying surfaces will have an important moderating effect.In the future, the regulatory effect of vegetation on water and sediment processes should be fully utilized. Strategies for sand control should be integrated with the management of river runoff resources to better protect the ecological integrity of river basins and promote sustainable economic and social development.