Water management in irrigation networks is crucial for sustainable agriculture under conditions of water scarcity and climate variability. This study applies the water accounting plus (WA+) framework, integrating meteorological and remote sensing data (WaPOR), to analyze water fluxes, productivity, and spatial heterogeneity in the Qazvin Plain irrigation network from 2009 to 2021. The total net inflow during this period was approximately 10,582 MCM, with contributions from precipitation (approximate to 20%), surface inflow (approximate to 27%), and storage changes (approximate to 53%). Analysis of evapotranspiration revealed that transpiration accounted for 80% of total ET, with 72% classified as beneficial (transpiration plus interception) and 28% as non-beneficial (soil evaporation and canopy interception). Spatial patterns indicate higher water availability in the eastern part of the network and deficits in the western region, highlighting the potential for improving water productivity through targeted interventions such as soil moisture conservation and optimized irrigation scheduling. These findings demonstrate the applicability of the WA + framework for enhancing water use efficiency and informing sustainable irrigation management in semi-arid regions.