Fig 1.
The generalized global sustainability model (GGSM): The water sector in the GGSM model consists of three compartments, namely, water reservoir, inaccessible water reservoir, and water recycling.
Water withdrawal by various sectors from the Water Reservoir is shown by dashed blue lines. Grey dashed lines indicate non-consumption water flows, that is, industrial and municipal water sent for recycling and the direct water transfer between the three compartments.
Table 1.
Variable description.
Fig 2.
Schematic representation of water system modelling: Green colored boxes represent historical/literature based data, blue boxes represent interim variables, yellow box represents model outcomes based data and orange box shows the final outcome.
Fig 3.
Sectoral intensity trends: The water withdrawal data (y-axis) is plotted against corresponding sector from the GGSM (x-axis).
Light green thick dashed lines show these trends. Exact equations are shown in Section S1 in S1 File.
Fig 4.
Validation of the sectoral water demand with respect to historical data.
Fig 5.
Geographical distribution of the water demand: The trends of regional values of the representative variables are extrapolated to the year 2120.
The contribution of each region towards the global value of each of the representative variables is depicted here. The historical data is shown by the markers, and the solid lines show the fits to historical data and the predicted data both. Detailed procedure of regional modelling in GGSM is provided in Section S2 in S1 File.
Table 2.
Summary of model parameterization.
Table 3.
Representative variables for water demand from different sectors.
Fig 6.
Global demand availability analysis: The top row plots show water demand projections’ absolute values, whereas the bottom row plots show the relative demand expressed in percentage.
The left column depicts the contribution of different sectors to total global water demand, whereas the right column shows a similar distribution for various regions.
Fig 7.
Regional water stress dynamics: Different levels of water stress as identified by the World Resources Institute are shown.
Specific timesteps are identified if and when the demand for a region crosses a threshold of 50% and 100% of its availability. The maximum value of the water stress is shown.
Fig 8.
Regional- sectoral water demand analysis: Specific timesteps are identified, if and when the contribution of agricultural demand for a region crosses 50%.
Fig 9.
Contribution of regions to the total demand by the sector.
Fig 10.
Population explosion: A comparison of water stress for the base case and population explosion case for the six regions is shown here.
Fig 11.
Mitigatory measures: A comparison of base case and 30% reduction in water demand of the agricultural water demand owing to the achievement of SDG 6.2 and SDG 6.4.