Land subsidence is commonly evaluated through the consolidation of saturated soils due to groundwater withdrawal; however, in arid and semi-arid regions with a thick vadose zone, this approach can significantly underestimate total deformation. To overcome this limitation, this study proposes a novel hybrid framework that integrates Biot's consolidation theory for saturated zones with a suction-based shrinkage model grounded in the Barcelona Basic Model (BBM) for unsaturated soils. The framework captures cumulative land subsidence caused by both aquifer exploitation and atmospheric evaporation. It is applied to the Willcox Basin in Arizona and validated using a five-year Interferometric Synthetic Aperture Radar (InSAR) dataset. The results demonstrate that shrinkage in the vadose zone contributes approximately one-third to one-half of the total observed subsidence, highlighting the crucial role of unsaturated soil deformation. Moreover, the rate of shrinkage-induced settlement decreased after the initial years of water table decline, likely due to the expansion of the soil's elastic domain as suction increased. Statistical validation yielded an RMSE of 34.84 mm, R2 of 0.98, and MAPE of 17.20 %, demonstrating acceptable agreement with InSAR observations. The proposed framework addresses a major gap in existing models and offers significant value for engineering geology, enabling more reliable subsidence predictions under varying groundwater and environmental conditions. Its design allows for practical application using either direct measurements or empirical estimations of input parameters, making it a practical and transferable tool for assessing land deformation under complex hydro-environmental conditions.