The world faces a huge challenge in balancing water demand for the growing populations andrneconomic development while protecting the environment with declining freshwater supply.rnDeficit irrigation (DI) and organic mulching (OM), understanding the water footprint (WF), andrnvirtual water will play a key role in sustainable water management in water-scarce regions. Thernmain objective of the study is to provide policy-relevant information by estimating the virtualrnwater flows and water footprint of major crops produced in the Nile Basin. The research consistsrnof four main components: first, a case study aimed to evaluate deficit irrigation management andrnits impacts on yield and water productivity of barley; second, evaluating of the blue water-savingrnpotential through deficit irrigation and mulching; third, a spatial analysis of the WF of majorrncrops in the Nile Basin; and, finally, an assessment of the annual variability and long-termrnchanges in WF and virtual water flow of selected crops in the Nile Basin countries. For the casernstudy, the barley has been selected as a target plant for multiple reasons. Firstly, barley is thernfourth most important annual cereal crop grown globally; secondly, the crop grows under arndifferent agro-ecological zone; thirdly, barley is both irrigated and rain-fed crop and commonlyrncultivated across upstream and downstream countries. To determine the irrigation amount ofrnbarely, the irrigation field experiment was arranged in a randomized complete block designrn(RCBD) with four replicates and five irrigation treatments (fully irrigated treatment (FIT), 90%rnFIT, 85% FIT, 80% FIT, & 75% FIT). The AquaCrop model & the global WF accountingrnstandard were used to calculate the WF of crops. For barley production at 80% FIT, the largestrnyield was recorded at 1700 kg/ha. The provision of a certain level of water stress (80% FIT)rnthroughout the growing season, translates to a better yield relative to full irrigation. The reasonrnfor the application of less water to provide a better yield might due to, Kc value, soil, and thernregional crop variety respond well to water stress. The FIT (2.01 kg/m3rn) and 80% FIT (2.95rnkg/m3rn) treatments had the lowest and highest water productivity, respectively. The findingrnindicates that barley production using DI offers great potential in improving water use. The bluernwater-saving potential of DI and OM, the spatial and temporal variability of WF was modeledrnusing the AquaCrop-OS plugin at a spatial resolution of 5x5 arc-minute grid cells for the yearrn1986-2015 based on a global data source. The blue WF of the selected crops was highest inrnEgypt, Sudan, South Sudan, and Tanzania. For the current situation, the total blue WF was 48.5rnkm3rn/y per crop, 89% of which falls in Sudan (55%), and Egypt (34%). Production of sorghumrnaccount for the largest share of the blue WF (50%) followed by maize (21%), and rice (16%). DIrncombined with OM showed to reduce the current blue WF by as much as 42%. Egypt and Sudanrnexclusively rely on irrigation water while the rest are based on rainfed in which other countriesrnneed to use irrigation for better production. Rainfall and evapotranspiration are highly variable inrnall production regions, which are the main drivers affecting the availability and distribution ofrnwater resources. Likewise, the findings show that there is a substantial difference in green andrnblue WF among crops across the Basin countries. The largest average blue WF (mrn3rn/y) in croprnproduction was found in Sudan, South Sudan, and Egypt. In Sudan, the crops with large WF are rnPage VIIrnmaize (6046m3rn/tonne), rice (5175m3rn/tonne), sorghum (2644m3rn/tonne), and milletrn(2160m3rn/tonne) and in Egypt, groundnut (3138m3rn/tonne). Egypt is the largest exporter of ricernwith an average net virtual water export of 810 Mm3rnper year followed by 19 Mm3rnin Sudan andrn16 Mm3rnin Egypt for groundnuts production. The results of this study have some relevant policyrnimplications and may be of great use in policy formulation. This research provided empiricalrnevidence of the potential blue water-saving; WF of crops and virtual water trade across the NilernBasin countries. Water-scarce countries like Egypt and Sudan can increase imports of waterintensive crops from relatively water abundant countries (upstream countries), and vice versa. Itrnis important to know the national virtual water trade with internal and external virtual waterrnflows in order to establish a sound national water policy. Virtual water trading can therefore helprnto sustain the water use of the regions in a sustainable manner. It is therefore necessary to usernevidence that satisfies the various criteria for the design, planning and implementation ofrnsustainable water resource management.