This study provides quantitative assessments of the impacts of efficiency enhancement for different types of irrigation water under water scarcity conditions. It employs a single country CGE (STAGE 2) model calibrated to an extended version of a recently constructed SAM for Egypt 2008/09. The SAM segments the agricultural accounts by season and by irrigation scheme, including Nile- and groundwater-dependent as well as rain-fed agricultural activities. The simulations show that Egypt should manage potential reductions in the supply of Nile water with more efficient irrigation practices which increase the productivity of Nile water, groundwater and irrigated land. The results suggest a more ambitious plan to boost irrigation efficiency for summer rice would be desirable in order to outweigh any potential shrinkage in output and exports. Furthermore, even doubling all non-conventional water resources is not sufficient to compensate the potential adverse impacts of Nile water losses. This highlights the importance of irrigation efficiency for the Egyptian economy.

Egypt's irrigation systems are inefficient; the use of water is profligate and soil salinity levels have risen. This has reduced agricultural yields and biased production patterns away from high value crops in favour of salt resistant crops. The need to improve irrigation water quality is accentuated by increasing demand for, and declining supplies of, water resources. This study uses a computable general equilibrium model, calibrated to an extended SAM and detailed satellite accounts for water quality, to assess the impacts of the huge investments needed to raise water quality. The results indicate strong positive economy-wide impacts in Egypt, which exceed the investment cost. Income increases by 4% and induce 24 increases in the production of high-value crops; i.e., fruits (almost triple), seasonal 25 vegetables (30-37%) and rice by (13%) with a 64% increase in rice exports. The 26 study illustrates the importance of including water quality as a variable in the 27 analyses of water systems.

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Nile water availability is one of the major constraints for agricultural development in Egypt. This study conducts a mixed multiplier analysis, under water and land constraints, to identify the seasonal agricultural activities with high output and income multipliers. It uses a 2008/09 SAM for Egypt with detailed representation for Nile-related production factors employed by agricultural activities across irrigation seasons. The results demonstrate the significance of addressing Nile water constraints not only for agriculture, but also for the overall economy. Policies that enhance water productivity, particularly in winter season, generate outstanding increases in output, income, and employment through sizable multiplier effects.

The agricultural sector consumes about 84% of the total actual water consumption annually in Kingdom of Saudi Arabia, therefore, the research depends on questionnaire data that was judged before being used in the study of a random sample of 355 farms from Al-Ahsa Oasis which irrigated with two types of water (groundwater, triple-treated wastewater) to measure the economic impact of the using of triple-treated wastewater in irrigating palm and lemon crops, the results indicated a statistically significant correlation between the extent of farmers'  which using of triple treated wastewater in irrigation and all of: size of the tenure, family size and the educational level of the farmer. While the relationship was negative with all of: age of the farmer, and number of years of his experience. The results showed that the productivity of dunums on farms irrigated with triple-treated wastewater increased by 0.32, 0.30, 0.22 tons, representing about 19.2%, 17.2%, 16.8% compared to which using groundwater for Alkhallas palm, Alrziz palm and lemon.