Author ORCID Identifier

Year of Publication


Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation


Agriculture, Food and Environment


Agricultural Economics

First Advisor

Dr. Michael Reed


The first essay compares six common models, linear, quadratic, Cobb-Douglas, translog, logarithmic, and transcendental, to estimate wheat yield and area functions for Saudi Arabia. Data cover 1990-2016 for all the variables that affect wheat supply. After testing the models using Box-Cox, multicollinearity, and autocorrelation tests, we decide that the Cobb-Douglas models provide the best fit for both yield and area. We find the price elasticity of wheat is inelastic. Yield price elasticities are more inelastic than area elasticities. The impact of government policy number 335 has a larger effect on area than yield. The cultivated area of wheat, the one-year lag of yield, and the number of machines per hectare are the most influential factors affecting wheat yield. The primary factors influencing the area models are a one-year lag of both cultivated area and yield, as well as the number of machines per hectare.

The second essay estimates the residual demand elasticity that rice exporters face in Saudi Arabia. The inverse residual demand methods, as proposed by Reed and Saghaian 2004, are used for rice exporters to Saudi Arabia during the period 1993-2014. Estimation results of the elasticities of the residual demand indicate that Australia, India, and Pakistan enjoy market power, while Egypt faces a perfectly elastic demand curve. We find Thailand and the US had positive inverse residual demand which means they also have no market power.

The last essay is about the virtual water trade in Saudi Arabia. Using the concept of virtual water introduced by Allan 1994 and developed by Hoekstra and Hung (2002), we estimate virtual water trade for 20 crops of Saudi Arabia during 2000-2016. Our result shows the average virtual water trade was 12.5 billion m3/year. Saudi has net virtual water imports, with the most significant virtual water imports coming from cereals & alfalfa and vegetables; and there is net virtual water export of fruit. Saudi virtual water trade reduces pressure on water resources by 52%. Distance plays a role in Saudi virtual water export; we found that more than 90% of exports go to neighboring countries, including 45% to GCC countries. More than 30% of virtual water imports come from Europe.

A Gravity model is used to investigate whether water scarcity variables influence trade. We compare the OLS, Fixed effects, Random effects, and PPML estimators to get the best model. The AIC, and tests for multicollinearity, and heteroskedasticity assist in determining estimation procedures and the final models. We cluster the errors by distance to improve the specific country effect variables such as economic mass variables. For the cereals and alfalfa group, we find that water-related variables influence virtual water imports of cereals, millet, sorghum, corn, barley, and sesame. Therefore, we suggest that a basic gravity model be applied to the other crops. In the vegetable group, we find that related water variables impact virtual water trade for all crops except marrow. Dates are the only fruit crop that are not influenced by the water-related variables.

Digital Object Identifier (DOI)

Funding Information

The Saudi Arabian Cultural Mission (SACM)