A practical method for completing the physical water supply table in the modified System of Environmental-Economic Accounts for Water (SEEA-Water) in Irrigation Districts Scale

The primary purpose is to introduce a systematic approach to determine the surface and groudwater resources contributions in the agricultural water supply as the primary basis for completing the physical water supply table in the customized System of Environmental-Economic Accounts for Water (SEEA-Water) to be employed in a scale of an irrigation district. The developed methodology is based on 1) spatial analysis of surface water distribution within the irrigation district upon the developed hydraulic simulation model for the main and secondary canals, 2) spatial evaluation of extracted water from exploitation tubewells located within the district, & 3) updating the agricultural water demands based on the dominant crops of the latest cultivation pattern and comparing it with the values of traditional water rights. Also, the parameters of the physical water supply table were customized in the SEEWA-Water framework that can be used for managerial purposes at the scale of an irrigation district. The effectiveness of the proposed method was investigated in the Abshar Irrigation District, Isfahan. Simulating the surface water distribution within the entire main and laterals off-takes conducted through developing an integral-delay simulator model. In this regard, surface water distribution regionalization and spatial analysis of water extracted from the aquifer were conducted in GIS and provided in the form of two separate layers. The update of agricultural water demand was carried out based on the latest cultivation pattern in the region using Netwat. The simulation results of surface water distribution indicated the decreasing trend of surface water distribution adequacy from upstream to downstream units in the two main canals and some laterals. The spatial analysis results were presented by determining the share of surface and groundwater resources by separating the entitled villages - based on the management point of view- and based on the main crops of the cultivation pattern, based on the water accounting point of view. Finally, the values of the customized parameters of the SEEWA-Water' physical supply table were calculated and reported. It needs to mention that in addition to the presented systematic method, the customized components of the physical supply table of the SEEWA-Water accounting method were presented in a way that can be employed in other Iranian irrigation districts.