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Sudanese irrigated agriculture faces water shortages if current methods of water use continue. This dissertation examines how Sudan can allocate its water share of 20.5 milliard cubic meters (MM) (7.6 MM for the Gezira Scheme) stipulated in the 1959 Nile Waters Agreement, given the physical climatic phenomena which affect the water. Land and water policies are examined using a dynamic model which determines optimal inter-crop (cotton, wheat, groundnuts, sorghum and vegetables), inter-temporal and inter-regional water, land, and labor allocation. The results show that land allocation ranges between 33,060 and 750,940 feddans. Cotton land is the most stable over the 50 year planning period. A stable path is interrupted by five to eight unstable years before returning to the same or different level for cotton, but by up to 16 years for wheat, groundnuts, and sorghum. Labor use is positively related to land use. Optimal water use ranges from 3.75 to 4.18 MM Discounted net present values, land values, and costs depend on crop yields, price policy, and the crop-water requirements. Control over land allocation, water distribution, and price in favor of cotton has a negative impact on income and water conservation. Population determines total subsistence consumption and resource allocation. Resources are diverted to food crops from cotton as population grows. Total subsistence requirements rise by 55% for sorghum to 133% for vegetables. Inter-regional analysis shows that Managil performs better than the main Gezira. The results imply that farmers benefit from the adoption of research station technologies, and that restricting land to produce cotton for export leads to inefficient water use and loss of income. Incomes drop substantially if free market prices are adopted without the freedom to allocate land. Such freedom, while representing a more rational approach, has negative implications for cotton production, and hence foreign exchange earnings. The Gezira Scheme is not using all its water share. However, shortages could develop if other schemes use more water, acreage increases, high water requiring crops are planted, the recommended 75% cropping intensity is realized, and a reduction in the Blue Nile flow by a drought and/or more water use by Ethiopia occurs.
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