To assess how the multiple processes that constitute irrigation land use interact, the basin-level hydrological model WASIM-ETH and a bioeconomic model MP-MAS were embedded into a common framework. Following conceptual integration of theories, we here describe the integration of data and joint calibration and validation of both models. Methodologically, interacting variables are first specified from data, then from model outputs, and then dynamically coupled. Interdisciplinary cross-checks and sensitivity analyses improved calibration. For irrigation management at basin scale, we indicate that physical scarcity of water, which restricts the current land use pattern in drier years, and allocative water scarcity which indicates inefficient water right markets, coexist in one basin, in different irrigation sectors. Also, due to heterogeneity of asset distribution among farmers, effective constraints vary considerably, so that water right consideration are not relevant to many. Thus, policies require in-depth analysis of the target groups at individual level.