This study determined the surface and groundwater resources portions aimed at identifying the contribution of water resources in an irrigation district by simulating the process of surface water distribution in irrigation canals, spatial analysis of water distribution. The Abshar irrigation district located in Isfahan city was selected as a case of this study. The simulation of water distribution within the canals was performed by the development of an integral-delay simulator model in the MATLAB, and the spatial analysis of the water distribution adequacy index was performed in the GIS. The water requirement of the crop pattern products was also estimated using the NETWAT program. The main and sub-canals' simulation results indicate a frequently decreasing of water delivery adequacy from upstream to downstream units, especially under the water shortage scenarios, indicating the poor efficient management of water distribution in the canal district. The spatial analysis of irrigation water distribution adequately indicated the inefficiency of surface water delivery and the main reason for the increase in the number of wells drilled by farmers within the irrigation district. Subsequently, by determining the amount of surface water portion in the second and tertiary agricultural area and analyzing the operation information of wells located in the irrigation district, the tables of the contribution of surface and groundwater resources were performed separately for the secondary and tertiary irrigated units. The results of this study provide the basis for implementing the water accounting system, with the portion of surface and groundwater resources within the irrigation district.