Water supply-demand imbalance was identified as a critical factor hindering agricultural sustainability in ecologically sensitive regions. Clarifying the water supply-demand dynamics in agricultural production spaces and implementing scientific irrigation management were crucial for ensuring food security and optimizing territorial spatial planning. Focused on the Luohe River Basin in the eastern Qinling mountains, the land use data (2000—2020), meteorological data, and geospatial datasets were utilized. A water balance assessment model was constructed by integrating the Penman-Monteith equation, FU’s formula, and an effective precipitation calculation model to precisely analyze water supply-demand equilibrium at a microscale grid level. A multi-agent spatial optimization model was further developed to delineate irrigation management zones. Key findings included as follows: agricultural land remained the dominant land use type in the basin, though its area was decreased by 1.90% during the study period, with its spatial center of gravity shifting first northeastward and then westward. Significant spatiotemporal heterogeneity was observed in actual evapotranspiration and effective precipitation. Higher values were detected in the southern basin and western Lingbao City, while weaker values dominated central-eastern areas. Pe exhibited a gradual decline from south to north. The water surplus-deficit in agricultural zones showed an overall decreasing trend, with surplus areas concentrated in the eastern basin and expanding deficit zones. Drought risk escalated from moderate to severe levels over time. The proposed irrigation zoning methodology effectively balanced water equilibrium characteristics and spatial aggregation benefits of farmland, resulting in five management zones, including priority control area, key focus area, orderly management area, moderate guidance area and adaptive production area. Customized irrigation strategies were recommended based on zonal characteristics. These findings provided scientific support for implementing a “water-determined land use” strategy in territorial resource management within the basin.