Humanity is facing an increasing challenge with respect to water scarcity (WS). This issue is driven by climate change, population growth, and socioeconomic growth combined with inadequate water resources management. In particular, there is considerable concern over virtual water (VW) transfers, which pose difficulties for water resources and food security sustainability. In this study, we assessed the i) VW content of crops, ii) VW flows, iii) WS, iv) water dependency (WD), v) water self-sufficiency, and vi) water savings/losses in African countries at different time series. We also addressed censorious issues and challenges for sustainable development in water-scarce regions. The results showed that the average net VW import was positive (108.9 x 10^9 m3/a). The WS values for East African countries were > 100, indicating overexploitation. In addition, the overall WD in Africa was 4655% in recent years. The trade of main grains between Africa and the rest of the planet corresponded to a global water loss of 2820.7 x 10^9 m3/a. However, a shift was observed in the ranking of commodities imported from one region to another owing to the evolution of a country’s economic development. The VW export of a country depended on the population size, gross domestic product, agricultural production, and area of arable land. Finally, we highlight opportunities for enhancing water use efficiency by increasing food production in water-scarce regions, thereby contributing to the achievement of Sustainable Development Goals.

Soil salinisation is vital factor limited crop yield in dryland oasis cropland. A film-mulched drip irrigation and subsurface pipe drainage (MDI-SPD) system has been proved its high efficiency all over the world. However, soil salt balance and simulation in time and spatial dimension are unclear in this system. Based on four-year observation data, we use HYDRUS-2D model to simulate the soil salt balance in a MDI-SPD system in western China. We conducted a set of MDI-SPD experiments three times in a field in Manas River Basin, western China: The laying depth of the subsurface pipe was 1 m, and drain spacing was 15 m. Three treatments were set at 0, 5, and 7.5 m horizontal from the subsurface pipe. Results after four years indicated that the total salt output in the irrigated area was 260.16 t, with 103.4 t salt drained by the subsurface pipe (39.74% of the total salt output in the irrigation area). Soil salt balance indicated desalination state. Soil EC response ranged from 8.33 to 11.21 dS m-1. The mineralization of subsurface pipe drainage was positively correlated with drainage flow and salt discharge, and negatively correlated with drainage discharges and time (P<0.05). If salinity leaching stops, 0−200 cm depth soil salt balance will achieve critical value in 8 years. Thus, we recommend salinity leaching once every three years. An increase in shaft drainage would also reduce the deep seepage of salt.