Accurate simulation of soil water dynamics in desert ecosystems is crucial for quantifying water balance and supporting management strategies. However, traditional models break down under the extremely low moisture conditions typical of arid regions. Based on field observations from 2018 to 2023, this study employed a complete moisture range model to simulate soil water dynamics from saturation to near-zero water content. It analyzed evaporation characteristics and soil water dynamics in gravel and sandy deserts and included future climate scenarios to assess long-term hydrological responses. Results showed that the model effectively captured soil water dynamics, with RMSE values below 0.02 cm(3) cm(-3) and NSE reached 0.74 in gravel desert and 0.84 in sandy desert. Despite differences in soil hydraulic properties, total evaporation between desert types showed no significant difference (P > 0.05). Annually, capillary water evaporation dominated, while film water evaporation contributed 3-8 % in the growing season and 20-75 % in the non-growing season. Gravel desert exhibited significantly higher effective soil water storage (ESWS) than sandy desert (P < 0.01). Under future climate scenarios, total evaporation remained similar across both desert types (P > 0.05), but sandy desert exhibited greater ESWS interannual variability, indicating higher sensitivity to climate fluctuations. In contrast, gravel desert displayed more stable water storage patterns. The findings enhance understanding of soil water movement and provide a basis for evaluating hydrological responses to climate change.