Abstract：Groundwater is essential to agricultural production and ecosystem functioning in the arid and semi-arid West Ordos region of China, an important production base for grain and cash crops. However, intensive irrigation and ongoing land-cover changes have substantially altered the regional water balance, while their respective impacts on groundwater dynamics remain poorly understood. Here, we employ the high-resolution ParFlow-CLM integrated hydrological model, locally calibrated using observed water table depth (WTD), to characterize the spatiotemporal variability of groundwater levels and storage and to quantify the effects of irrigation and land-cover change. The calibrated model reproduces observed groundwater dynamics well, with correlation coefficients exceeding 0.8 in intensively irrigated agricultural areas. It captures both seasonal waterlevel fluctuations and longer-term trends, demonstrating its ability to represent groundwater responses to human water use. Across most of the study area, the multi-year mean WTD ranges from 30 to 50 m. Groundwater levels decline from late spring to early summer, corresponding to an increase in WTD during the period of elevated water demand, and recover during autumn and winter. This seasonal cycle is closely linked to the timing and magnitude of surface water and heat fluxes, as well as to the seasonal distribution of irrigation and groundwater recharge. At the regional scale, irrigation pumping is the dominant driver of groundwater storage depletion, accounting for 86.1% of the attributed change and resulting in a cumulative reduction of approximately 633.6 million m³. Groundwater storage exhibits a stepwise decline because substantial losses during the growing season are not fully offset by recharge during the non-growing season. In contrast, land-cover change produces an overall positive effect on groundwater storage, accounting for 13.9% of the attributed change. Among the land-cover transitions, grassland expansion associated with ecological restoration represents the primary positive contributor. These findings demonstrate that irrigation pumping and ecological restoration exert contrasting influences on groundwater resources in West Ordos, with irrigation-induced depletion substantially outweighing the gains associated with land-cover change. The high-resolution modeling framework and quantitative attribution approach adopted here provide valuable tools for identifying groundwater vulnerability and disentangling the effects of human activities and ecological processes. The results also highlight the need to improve irrigation efficiency, regulate groundwater abstraction, and coordinate agricultural development with ecological restoration. Overall, these findings provide critical scientific underpinnings for the sustainable management of groundwater resources and ecological protection in arid and semi-arid regions.