My Personal Issue of the Week: the Falkenmark Water Stress Indicator

The most widely used measure of water scarcity is the Falkenmark Water Stress Indicator, developed in 1989, which states that water availability below 1700m³/capita/year causes regular water stress. Availability below 1000m³/capita/year is classed as water scarcity that threatens human health and economic development (and below 500m³/capita/year indicates absolute scarcity). Indicators are instruments to simplify large amounts of data, and Falkenmark’s measure achieves this successfully. However, attempting to aggregate water requirements and water availability into a single measure loses important information. One such limitation of the Falkenmark Water Stress Indicator is that it only considers renewable surface water and groundwater flows within a country. Moreover, averaging water availability across a spatial and temporal scale neglects water shortages that occur during dry seasons, and at smaller regional scales. Furthermore, it does not account for the quality of the water, nor does it describe the ability of the country to make use of the resource. All of these limitations apply with particular clarity to African countries, for reasons that have been described in previous posts.

The Falkenmark Indicator is highly useful because it is understood intuitively; however, an indicator that is applied so extensively in the realm of social development should also hold steady the crucial meaning of the challenges under consideration. To me, a key limitation of the Falkenmark Indicator is not the loss of information, but the loss of action. Preoccupation with one measure promotes lethargy in two dimensions: first, if the parameters of the indicator are adjusted, different countries become ‘water scarce’, meaning the label of ‘water scarcity’ has less weight and the tackling it appears overwhelming; second, if the indicator is used in relation to a single discourse, any challenge to that discourse that emerge, including from the indicator itself, are ignored. I would like to illustrate this in the following ways.

Firstly, explicitly accounting for the water needs of ecosystems pushes many ‘developed’ countries into apparent water scarcity, including large parts of Europe, North America and Australia. The competition between ecosystems and irrigated agriculture in these areas is not at the forefront of the discourse, perhaps because large-scale water use already blends seamlessly with economic and development success. The term ‘water scarcity’ often brings to mind domestic shortages; for drinking and sanitation, but this is fractional compared the water requirements of agriculture and industry. Domestic water use is not affected by scarcity in the physical sense, but by supply infrastructure, poverty and politics. Therefore, it follows that a sensible application of the thresholds proposed by Falkenmark is to indicate that water is becoming scarce for food production, particularly in arid or highly climatically variable parts of Africa. Why then, is the continent pushed towards a ‘Green Revolution’, a plan for agricultural production that involves massive water use? Furthermore, on a more technical note, it makes little sense for the Falkenmark Indicator to be heavily linked to water scarcity for agriculture when soil moisture, the recipient of a large proportion of annual rainfall, is excluded from the measure.

Another theme that arises from the Falkenmark indicator the negative impact of population growth on water resources: population growth essentially multiplies the water requirements set out by Falkenmark et al., while the amount of surface water and groundwater remains relatively constant. However, daily water needs are likely to be dynamic, and dependent on income, lifestyle and attitude. Currently, it appears this flexibility in water use will only exacerbate scarcity; in the 20^th century the world population tripled, but water use increase six fold². The potential impact of attitudes and lifestyle can alternatively be seen as an opportunity for positive change. This can be seen in the energy sector, with the achievement of increasing efficiency and the adoption of corresponding values. Of course, there is far more to achieve regarding energy use, but what is often most important, and most difficult, is initiating a change in the existing system.

A similar change needs to happen within the current paradigm of water use, particularly for agricultural production. In my opinion, there is little point in the ability to say, “this area is water scarce”, when nothing is done about it. While the value of the Falkenmark Indicator remains in situations where information needs to be conveyed quickly and simply, measuring water scarcity should include more observational and longitudinal measures. It is a near consensus that water management needs to be more participatory, seen in the increasing popularity of ‘integrated resource management’, but true democratic participation is likely to emerge from communities and regions being able to say “WE are experiencing water scarcity”; rather than a distant indicator labeling them as such. More importantly, action should follow any observation or confirmation of water scarcity. This is more likely to be achieved with decentralised, efficient and adaptable strategies that focus on two key areas of water: maintaining soil moisture, for example through controlled flood releases at dams, the use of terraces (such as in Machakos, Kenya) or simply encouraging a diversity of moisture-retaining plant species on farms; secondly, a focus on developing highly productive strategies of micro-irrigation, such as drip irrigation^{3, 4}. The Falkenmark Indicator, whether intentionally or not, places the individual user at the centre, therefore the individual users should be given the capacity to adapt to water scarcity effectively.

¹ Rijsberman FR, 2006. Water scarcity: Fact or fiction? Agri Wat Manag, 80(1-3): 5-22.

² Cosgrove WJ & Rijsberman FR, 2000. World Water Vision: Making Water Everybody’s Business. London: Earthscan Publications.

³ Gleick P, 2003. ‘Soft Path’ solution to 21^st-century water needs. Science, 320(5650): 1524-28.

⁴ Postel S, 2001. Safeguarding our water – Growing more food with less water. Sci Am, 284(2): 40-45.

⁵ NTUA. Indicators and indices for decision making in water management. EEMRU Newsletter. Accessed 30/12/16 from http://environ.chemeng.ntua.gr/WSM/Newsletters/Issue4/Indicators_Appendix.htm