The literature on transboundary water resources allocation modelling is still short on encompassing and analyzing complex geographic multiparty nature of basins. This study elaborates the Inter Temporal Euphrates and Tigris River Basin Model (ITETRBM), which is a linear programming based transboundary water resources allocation model maximizing net economic benefit from allocation of scarce water resources to energy generation, urban, and agricultural uses. The elaborations can be categorized in two directions: First, agricultural and urban demand nodes are spatially identified with their relative elevations and distances to water resources supplies (dams, reservoirs, and lakes). Digital elevation model (DEM) database are intensely processed in geographic information system (GIS) environment. Second, the agricultural irrigable lands are restructured into a pixel based decision making units (DMUs) in order to be able to see the spatial extent of optimally irrigated land, and then optimization program is converted from linear programming (LP) to a mixed integer programming (MIP). The model applications are designed to cover a series of sensitivity analyses encompassing the various transboundary management, energy and agricultural use value, and transportation cost scenarios over the optimal uses of the Euphrates and Tigris Basin (ETRB) resources. The model results are visually presented via GIS in order to show the transboundary upstream and downstream spatial impacts of these selected parameters. The findings are i) system parameters significantly alter the spatial extent of water resources allocation in the ETRB, and ii) the magnitudes of the parameters also explains the tradeoffs between agriculture and energy sectors as much as upstream and downstream water uses of countries.