Appendix : Modeling the impacts of water-land allocation alternatives on food security and agricultural livelihoods in Egypt: Welfare analysis approach

This supplementary document illustrates the major components of the hydroeconomic, and welfare analysis model used and applied for the Nile Basin of Egypt. The documentation is organized in five sections, starting with the table of major sets and subsets, parameters, variables, conversion units and followed by a list of the main equations used in our model. The sets and subsets refer to the dimensions over which the model is defined. Parameters are the major data inputs used in our model, while variables are the unknown values to be estimatedinternally by the model. The list of conversion units shows the conversion of local units to international units. Major equations that define the relationship between different variables in the model are shown also. The modeling is developed using General Algebraic Modelling System (GAMS) software. The model comprises one headwater flow, 10 river gauges nodes, 13 diversion nodes, 13 consumption nodes, 13 return nodes, 13 unaccounted water nodes, two reservoirs, 22 crops, three irrigation seasons, a 10 years’ time span, and four optimization policies. Those elements are integrated and comprise 40 block equations containing 132,600 single equations. The model also contains 30 block variables that makes 185,496 single variables. The model has been applied to Egypt’s part of Nile Basin as a case study. The current model is an update and development of simpler version published by Gohar and Ward (2010, 2013).