الفهرس 
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Abstract
Sustainable Groundwater Management for New Reclamation Areas in Egypt
Egypt’s agricultural land is very limited with respect to its population food demand. This leads Egypt to be a heavily dependent on imported food products. To fulfil the expanding demand of agricultural products, successive governments have initiated many land reclamation projects since 1930s. In 2014, the Egyptian government initiated an ambitious horizontal expansion plan through reclamation of about 1.5 million feddans (1 feddan = 4200.83 m2) as part of sustainable economic development aligned with Egypt’s vision towards 2030. The majority of this project areas depend on groundwater as the only source of irrigation water. There is a great concern about groundwater sustainability which considered the main challenge to this project.
The Western Desert of Egypt is one of the main regions of the 1.5 million feddan project, including oases and southern area. These oases are characterized by artesian wells with high flow rate of fresh water which extracted from the Nubian Sandstone Aquifer (NSA), a huge nonrenewable aquifer. It stores about 150,000 BCM (km3) and it is considered the main water source for this region.
Intensive well-drilling process in NSA area has been going on since 2014. This may result in developing huge drawdown around the well fields which leads to lowering the groundwater potentiometric (piezometric) level (GWLpotent.) and occurrence of undesirable consequences. It is extremely important to sustainably manage groundwater extraction from this aquifer. Sustainable extraction rates and the most beneficial sustainable extraction rate have to be determined.
However, safe yield concept, outflow equals inflow, is not applicable for NSA. Sustainable groundwater management definition for nonrenewable aquifers is not unique because compromising between benefits of groundwater exploitation and its negative side effects is different from case to another. Hence, groundwater sustainability assessment and management criteria are determined on case by case basis.
A new groundwater-dependent reclaimed area of 10,000 feddan in Sahl Baraka, Farafra oasis, was taken as a case study area. For the study area, the Egyptian Government, represented by the Ministry of Water Resources and Irrigation (MWRI), set the limits of the adopted sustainable groundwater management criteria. These limits depend on two factors of the same weight. The first factor is the range of the economic lifting depth (Economic Dlifting) (set to be ≤ 40m beneath the land level (LL) at well location). The second factor is the duration during which the lifting depth (Dlifting) becomes not economic (set to be at least 100 years). Lifting depth (Dlifting) could be defined as the distance between the land level (LL) and the groundwater potentiometric level (GWLpotent.) at the well, including the Depression Cone Drawdown (DDwell).
GIS functions were used to develop the initial groundwater potentiometric map. 3-D MODFLOW model, for the study area, was constructed, calibrated, and run to obtain the Depression Cone Drawdown (DDwell) associated with different extraction rates. All NSA regional drawdown rates at Farafra oasis were considered. Methodologies for duration and lifting depth sustainability assessment, using Benefit-Deficit analysis, have been developed and applied. Also, methodology for determination of the most beneficial sustainable extraction rate has been developed and applied.
Groundwater sustainability for extraction rates Qwell = 1000, 2000, 2500, 3000, 4000, and 5000 m3/day have been assessed, according to the MWRI adopted sustainability criteria. It could be concluded that all considered extraction rates are sustainable for the duration criterion. However, extraction rates Qwell ≥ 4000 m3/day are not sustainable, for the economic lifting depth after 100 years criterion. The most beneficial sustainable extraction rate for the study area has been determined, according to the adopted sustainability criteria, and found to be Qwell = 3000 m3/day.
Another approach towards sustainable management of groundwater resource, particularly, for that extracted from nonrenewable aquifers, is maximizing physical and economic water use efficiencies. Applying sprinkler and trickle irrigation in all newly reclaimed areas in Egypt insures physical groundwater efficient use. However, economic sustainable agricultural groundwater use needs to be discussed and evaluated. It is related to the crop economic water use efficiency (CEWUE), which is based on Crop Net Return per unit volume of consumed water. Maximizing the CEWUE leads to the highest economic return of agricultural groundwater.
Applying the previously discussed sustainable extraction rates, economic agricultural groundwater use for all suitable winter crops, medicinal and aromatic plants, and summer crops, suggested by the Ministry of Agriculture and Land Reclamation for the study area, were discussed. Values of CEWUE were determined and the suitable crops and plants were ranked accordingly. Tables and charts have been developed and presented showing the available data, results of the analysis, to help decision makers in maximizing the economic groundwater use and to simplify its management.
Studying the economic groundwater use for all crops and plants suitable for the study area, it could be concluded that Dry Onion is the best winter crop, followed by Sugar Beet, Lentil and Wheat. Cultivation of Barley and Broad Beans is not economically groundwater use efficient compared with other winter crops. They should be replaced by more efficient economic groundwater use crops, if it is accepted from the strategic food security aspect.
Cumin is the best medicinal and aromatic plant, from the economic groundwater use point of view, followed by Fennel and Caraway. Cultivation of Coriander is not economically efficient and should be replaced by more efficient economic groundwater use plant.
Peanuts is the only efficient summer crop, from the economic groundwater use point of view. Sunflower, Soybeans, Maize and Summer Sorghum are not economically groundwater use efficient and should be replaced by more efficient economic groundwater use crops, if it is accepted from the strategic food security aspect. It is recommended that Cultivation of summer crops, except Peanuts, should be avoided to conserve groundwater storage or increase the reclaimed area to cultivate more economic groundwater use efficient medicinal and aromatic plants, and winter crops.
Assuming that every crop pattern has an only one crop or plant to cultivate per season and according to crops cultivation start and end times, twenty-four crop patterns were discussed. Crop pattern economic water use efficiency (CPEWUE) was determined and presented, for all available crop patterns suitable for the study area. charts for crop patterns ranking, according to their groundwater use efficiencies, were developed and presented to decision takers and managers. charts showing A1 and A2 relation, CPEWUE, and % Relative CPEWUE Index were developed for all available crop patterns, using excel spread sheets.