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Running low?
Water is becoming scarce, so use it productively! A reminder for World Water Day, which falls on March 22 by Professor Frank Rijsberman
During the last five to ten years, water issues have been prominent in the global agenda, due to the perception that a world water crisis is imminent because of an increasing scarcity of water.

But what is the true nature of the ‘water crisis’ in the world and in Sri Lanka? And what do we really mean by ‘water scarcity’? Is the world or Sri Lanka really running out of water? And if so, what are the implications? What is water scarcity?

The abundance or scarcity of water has been of interest to researchers for some time, and several methods for calculating water scarcity at various geographical scales exist, each with its own strengths and weaknesses.

The most often quoted indicator or measure of water scarcity is the Falkenmark Indicator, which relates the more or less fixed amount of renewable fresh water resources in the world to population, using a per capita estimate of water required to satisfy domestic, agricultural and industrial needs. This method suggests that a country with less than 1,700m3 of water per person per year will experience water stress, and that this becomes acute at less than 1,000m3 per person per year.

From a water management point of view, however, this calculation has little use, as it does not tell us what the actual demand for water in a country is, and whether or not the amount of water available is adequate to meet this demand. It also ignores the fact that demand will vary from the relatively small quantities used by households (50 litres per person per day), to the much larger requirements of agriculture (2,000 to 5,000 litres per person per day, depending on diet), industry and the environment.

More accurate assessments of scarcity therefore focus on relating available water to the demand for water, rather than to population. Some have gone further and replaced water demand with water withdrawals (the amount of water taken out of rivers, streams or groundwater aquifers to satisfy human needs) to more accurately assess actual water use. They present scarcity as the total annual withdrawals as a percent of available water resources, in what is referred to as a water resources vulnerability index. They suggest that a country is water scarce, if annual withdrawals are 20% of annual supply, and severely water scarce, if this figure exceeds 40%. As can be seen, these methods become more complex as their creators strive for greater accuracy.

Whilst these scarcity indicators may help us estimate overall water demand and supply relationships at global, regional and national levels (i.e. at quite large geographical scales), what is of particular importance for water management decision making is understanding the variations in water availability and demand that occur within each country, and their underlying reasons. For instance, a healthy water balance for a country as a whole does not necessarily mean that people do not suffer water stress. Some areas may be almost permanently dry (arid) with low levels of rainfall throughout the year, while others may experience extremes of floods during some months of the year and droughts in other months. This would indeed describe many parts of Sri Lanka, as well as many other developing countries, especially in South Asia.

National aggregates of water availability clearly hide considerable variations caused by natural characteristics within a country. This variation becomes more pronounced when certain human activities or responses influence the natural dynamics. The most obvious human impact is of course changes in the use of water. While some sources may attribute lower rainfall for the severe droughts in the Hambantota district in recent years, an alternative explanation is an increase in water withdrawals as populations grow.

Perhaps less obvious are responses that have a positive impact on water availability. For instance, societies with the resources to adopt coping mechanisms (such as water storage, supply infrastructure and efficient allocation rules and institutions) will be better placed to store excess water during monsoons, and make it available during the dry season.

Similarly, societies that can invest in water purification will be able to re-use the same water (such as re-using of domestic/industrial waste water), thereby effectively increasing the amount of usable water. Finally, some countries may prefer to deal with water scarcity by importing a large part of their food supplies, thereby saving water within the country, but effectively using water from the exporter where the food was grown.

The International Water Management Institute (IWMI), the world’s premier research institute on water and agriculture headquartered in Sri Lanka, divides water scarcity into three types that reflect the different reasons for scarcity to occur in each case: absolute or physical scarcity, economic scarcity and institutional/political scarcity.

Absolute or physical water scarcity refers to a situation where a country or river basin does not have enough water to satisfy its needs, even if it takes all reasonable measures to increase available water supply and maximise its use efficiency (or productivity). Many such countries will not be self-sufficient in food production and will have to import part of their food.

Economic water scarcity refers to countries or basins that have the water resources to satisfy their demands, but would have to develop new infrastructure, such as dams and reservoirs, in order to make this water available to the people who need it at the appropriate time.

Finally, institutional or political water scarcity refers to people not having access to water, even if the resources and infrastructure are available, due to inequities in access to the resources, due to various political or social reasons.
An assessment by IWMI of water scarcity in Sri Lanka at district level demonstrates how aggregated information at national level may mask issues of local water scarcity. While absolute scarcity is not the case overall, a substantial area of the country was found to experience severe water-scarce conditions, while other areas showed only moderate or no scarcity.

The degree of scarcity also varies over time – five districts in the maha season, and nine in the yala season already withdrew more than 50% of their water resources in 1991. These districts already have absolute water-scarce conditions according to some criteria. A few more districts will enter into the absolute water-scarce category in 2025 under scenario1 (Figure 1). However, if the irrigation sector efficiency can be doubled by 2025, only four districts in the maha season and nine in the yala season will have severe water-scarce conditions.

On a larger scale, the dry zone accounted for more than 90% of current water withdrawals (mainly due to the higher share of irrigation demand), whereas only 44% of the population lived there in 1991. Demand projections for 2025 show that the dry zone will continue to absorb over 90% of total water withdrawals. With increased irrigation efficiency, however, total demand in the country (and especially in the dry zone) can be reduced by almost half.
So what does the future hold for the world and for Sri Lanka in relation to water availability? What does it imply for the way we should manage water? A similar exercise to that in Sri Lanka was carried out by IWMI at the global scale, where economic water scarcity was found to be the predominant form of scarcity, while many other countries were projected to experience no scarcity conditions (Figure 2).

Thus, the challenge for most countries, including Sri Lanka, at least in the short to medium term, is not a lack of water in absolute terms, but how to utilise it more efficiently and equitably. In other words, it is a) how water can be made safe and accessible to the unserved for domestic use and sanitation, and b) how it can be used more productively to free the poor from poverty and food insecurity, while accommodating the rapidly increasing needs for urban and industrial sectors and without further jeopardising the environment.
Analysts have approached this question by projecting changes in water use, if society continues to use water in the same manner it does today (‘business-as-usual’ model), and by considering the impact on future water use, if we did change our behaviour to use water more productively. Analysis of many years of national data shows that ‘business-as-usual’ would lead to some 25% increase of water withdrawals between 2000 and 2025, from 4,000 km3 withdrawn to 5,000 km3 abstracted, and from 2,200 to 2,800 in terms of cubic kilometres consumed. But in many countries, there are clear signs that this vision is not sustainable.

While continued human population growth will be a factor, the primary reason stems from the fundamentally different way many researchers have come to view water. This difference lies in seeing it not from a particular user’s point of view, but from a holistic view that recognises that water has many roles, direct roles in the lives of people and indirect ones through maintaining a healthy natural environment, which after all, is the basis of all life on Earth, including ours, our children’s and generations to come.

This view is very different to how water has been used in the past, and is still used today in many countries, where the primary use has been for food production – between 70 – 80% of available water. Until recently, urban centres have been relatively small (and domestic requirements are small anyway), and large-scale industrial processes too are relatively new to many countries. What of the environment? It was seen more as a source of water, rather than a user, and hence usually, did not enter the equation at all!

That so much water is used for agriculture is understandable, given it is a basic necessity for life. So long as population densities were modest, there did not seem to be much of a problem. When food production concerns did arise in the 1960s, technologcal means of increasing yields (primarily chemical fertilisers and pesticides) seemed to have solved the problem. Yet, today, the growth of cities and industries, and a greater awareness of the need to leave enough water in our rivers and lakes for nature (environmental flows) require us to reconsider water allocations between different sectors. In the Murray Darling basin in Australia, for example, abstractions have been capped and restoration of environmental flows is now a priority.

Elsewhere, such as in the Yellow River in China, the Yellow River Conservancy Commission has pledged to reduce withdrawals for agriculture by 10% over the next ten years.

So, where does this leave agriculture, if it is seen as the source that will have to shrink its water use to allow expansion for cities and industry? The answer is not in the collapse of the nation’s agricultural heritage, but in increasing the productivity of water used in agriculture that will free water for other users, while continuing to produce enough to feed the world’s population. In fact, failure to make this transition is likely to be very damaging to agriculture.
(The writer is Director General of the International Water Management Institute (IWMI), Sri Lanka)

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