3.4. Level of water stress at major river basin level

FACT BOX

According to the United Nations Office of the High Representative for the Least Developed Countries, Landlocked Developing Countries and Small Island Developing States, Small Island Developing States (SIDS) tend to face similar constraints in their sustainable development efforts, such as a narrow resource base depriving them of the benefits of economies of scale; small domestic markets and heavy dependence on few external and remote markets; high costs for energy, infrastructure, transportation, communication and services; long distances from export markets and import resources; low and irregular international traffic volumes; little resilience to natural disasters; growing populations; high volatility of economic growth; limited opportunities for the private sector and a proportionately large reliance of their economies on their public sector; and fragile natural environments. These factors make SIDS particularly vulnerable to biodiversity loss and climate change because they lack economic alternatives.

Source: United Nations Office of the High Representative for the Least Developed Countries, Landlocked Developing Countries and Small Island Developing States (2021).

For this report, information to compute indicator 6.4.2 was only available in less than 50 percent of SIDS (Figure 12). This is the result of the fact that – as previously mentioned – in many cases, EFR values are not available in SIDS. This, in turn, is due to the limitations of the GEFIS system used to estimate environmental flows, which does not allow the assessment of the parameter in very small areas.

Water stress in SIDS is generally very low, with exceptions such as Barbados and the Dominican Republic whose main water use is related to agriculture, and Singapore, whose main water use is urban supply.

In large archipelagos such as Fiji, variables such as climate, water availability and population density are very heterogeneous. Further disaggregation of the indicator will be necessary to capture a more accurate value of water stress in those situations.

Following the thresholds established for this indicator (see section 2.2), major river basins with an indicator level lower than 25 percent have no water stress. Those basins with a water stress level greater than 75 percent have high or critical water stress. High values of water stress mean more water users are competing for limited water supplies. As shown in Figure 13, water stress is evident in all the basins characterized by intensely irrigated agriculture, as well as in those including densely populated cities (for example, Cape Town) which compete with the agriculture sector for the use of water, and where there is less volume of available freshwater resources due to climatic conditions. Overall, the results shown in Figure 13 are aligned with what is shown in the map of water stress at country level (Figure 7).