Thursday, September 27, 2007

Elementary Errors Compounded

In the Handbook of Water Resources in India (2007) several authors bemoan the low per capita water storage in India. These include John Briscoe and RPS Malik (pg. 2), A Sekhar (pg. 63) and RPS Malik (pg. 142), well known and influential names.

Mr. Sekhar, Advisor to the Planning Commission, even says that one of the main reasons for water problems in the country is the low per capita storage. He adds that India has no option but to go ahead with its dam construction programme. This is quite incredible for in the vast number of articles in book (including by these authors and others) the problems discussed and the solutions offered are quite different.

Nevertheless, it may well be that the authors are merely inconsistent in their views. The question may still be posed. Is there merit in the augmenting water storage?

The reason proffered by these authors is that rainfall is concentrated in a few monsoon months making storage inevitable. Further, the per capita water storage in India at about 265 cubic metres (see Tables 1.8 &1.9 and Chart 4 of this report) is much less than that of other countries. While Briscoe and Malik say that arid-rich countries like USA and Australia have over 5,000 cubic metres (m^3), middle-income countries like South Africa, Mexico, Morocco and China have a storage capacity of about 1,000 m^3. Interestingly, Mr. Malik in a later chapter offers somewhat different figures – 1964 (USA) and 753 (South Africa). He also points out that dams on the Colorado (USA) and Murray-Darling (Australia) can store 900 days of river flow; India can store only about 30 days of rainfall.

The comparison is with a select list of countries (why only these and not other countries make it to their list and why global averages are not presented is a moot point but I will let that pass for the moment). The interesting that is that most of the countries mentioned - Australia, Spain, China, USA and South Africa - face varying levels of acute and chronic water-related problems including that of scarcity. Water storage hardly seems such a silver bullet after all.

Mr. Sekhar also suggests the need for a storage capacity of 750–1,000 m^3 per capita though the rationale of that figure is not explained.

In any case, what matters is the ability of a country to meet its requirements - to provide water - and not its storage capability. India’s per capita availability of 1,700 m^3 per capita per annum is considered quite comfortable. As I pointed out earlier, several countries with higher storage have not solved their problems while several countries (e.g. in the Gulf) with less storage manage quite well. In fact if a country can meet it use without storage so much the better.

Since rainfall in India occurs over a few months it is, of course, imperative to store water. Let’s examine this more closely.

Note that the Indian storage estimates – approximately 300 billion cubic metres (BCM) (265 m^3 per capita) - relate to major (more than 10 million m^3) and medium facilities with the former accounting for almost all of it. This excludes the tens of thousands of small storage structures in the country that collectively store considerable quantities of water.

A major source of surface storage is water in the form of snow, something not considered by the authors at all. This is a free and valuable form of storage and the melting of snow provides water in a very regular and dependable manner, though admittedly the water is not accessible the way it is from other sources. Yet it is a form of storage that hardly deserves to be excluded. In another essay in the book (pg. 184) a figure of 200 BCM of annual water flows from snowmelt is mentioned and one can derive a figure of 800 BCM of storage in the form of snow (700 m^3 per capita), a figure hardly to be scoffed at.

Nor is water stored only above the ground. It is stored below the ground (in shallow and deep aquifers) and which provides near-free and low evaporation capability. As is well known by now groundwater is a considerable source of supplies to irrigation, domestic and industrial users. Aggregate storage below the ground would dwarf surface facilities by a large margin.

(Now it is true that other countries storage capacities too will increase if we include all sources but as I have pointed out overall storage per capita may not be a useful way of looking at things.)

There is also the whole issue of the source of water for storage. If water is not being stored today where is it going? Is it flowing to the seas? Recharging groundwater? Or is it evaporating? Surface storage in large dams would make sense only in case of the last of the three. For as the authors themselves recognise water flowing to the seas is not a waste. And if it were to be captured from what goes to recharge groundwater it would be a zero-sum game.

Finally, it is in the Ganga-Brahmaputra-Meghna system that the bulk of the storable potential exists but water shortages are endemic in the arid parts – select regions of north, western, central and southern India. Enhanced water storage is unlikely to benefit these areas.

(This post may be read along with the others on Water.)

Thursday, September 20, 2007

Water Woes in Chennai: Quick Comments on RWH and Desalination

In a recent post I had discussed the potential for desalination as a solution to shortages of water and had made a reference to Chennai. The intention was not to discuss the water problems of the city at any length. The city’s water woes are well known but not well studied.

One attempt to redress the lacuna is the work of A. Vaidyanathan (done jointly with J. Saravanan). Readers may read the relevant chapter in this book. Based on a survey of households carried a few a years ago it provides information on several aspects such as consumption, sources of supply and costs. Care must be taken in interpreting and drawing conclusions from the study as it had several limitations, which the authors themselves highlight. It does provide a broad overview of the water issues including discussion on conservation, rainwater harvesting (RWH) and other supply augmenting measures.

While the work is useful it lacks conceptual clarity. If suffers from most of the errors I had pointed out in an earlier post. We don’t get a water balance for the city that would take into account the way water is received, stored, used and disposed.

For example, while discussing RWH the authors don’t tell us where does the water go if it is not harvested. Does it flow out to the seas or to tanks or lakes that dot the city or in to the marshes or other natural bodies? Does RWH increase overall water availability or does it just redistribute it? Does local availability increase? Is it a zero-sum game?

(This is an important issue especially in urban areas. In rural areas local harvesting has much stronger rationale though the issues are relevant there too. See, 1 and the responses to it - 2 and 3.)

There is also the issue of RWH on individual structures. Even if water is to be harvested locally must it be done on each and every building rather than in a collective enterprise? Making RWH compulsory as was done in Chennai is also likely to lead to corruption, or people putting up token structures that are not effective to begin with or then failing to maintain them.

Desalination is dismissed in one paragraph, which is surprising as the book has been written in 2006 by when a lot of initiatives in Chennai had been taken up. As mentioned in an earlier post this augmentation measure may have great potential and impact.

Chennai is interesting not only because it suffers acute and chronic water problems; relies on water from surrounding and far-off areas with attendant problems; but also because it is on the coast where desalination can be an attractive proposition.

Thursday, September 13, 2007

Desalination in India: Some Comments

It is not for nothing that Earth is called a blue planet. Not only is 71 % of the surface covered by seas, the water they hold is so unfathomably large (in relation to what circulates in the hydrological cycle) so as to be considered infinite. See here.

Removing salt from water is rather easy - boil it and then condense the vapours in another vessel, - and in the bargain get salt, as well. The issue has always been of the cost – primarily energy.

Developments in the past decades have dramatically reduced these costs – present estimates range from 50 to 80 cents (Rs. 20-32) per cubic metre (1,000 litres) of water. (See 1, 2 and 3), though in India a figure of Rs. 50 is also quoted. Costs are most sensitive to the level of salt in water (the lower the salt content the cheaper it is to desalt - so treating brackish water is cheaper) and energy costs. Note that the above costs are that of desalinisation and don’t include those of distribution. Transporting water over long distances (which may also entail lifting it) can increase considerably the final delivered cost of water.

There are two major technologies for desalting water – reverse osmosis (RO) and multi-stage flash (MSF); the former is increasingly more popular. RO is modular in nature and capacity ranges are wide. Another point to the noted is that while the cost of desalination is going down that of conventional water is going up as fresh supplies come from deeper aquifers or water is transported over longer distances. (See above citations for details including on costs, technologies and other matters. See also the references in the sources cited above.)

Given that so much water is available, costs are falling, traditional sources are turning dearer and more difficult to tap, and that there are severe shortages in several coastal location (Chennai is the example that springs to mind) is there a case for desalting water on a large scale?

Apart from Chennai, several other cities on the lower east coast and in Gujarat would seem to hold immediate potential. At present Chennai is building several desalination plants for both domestic use and for industries. See 1, 2 and 3.

Another interesting possibility is that if coastal areas can develop their own independent water supplies it may relieve pressures on upstream water resources that currently supply water to these locations. In other words, water which is now required for downstream users can be saved and used upstream. Hence, desalted water may have a role in helping upstream water users too!!

Desalted water is undoubtedly more expensive, say 2-5 times (numbers are illustrative) the cost of conventional water and it is feared that overall costs of water would shoot up considerably if it were to be adopted on a wide scale. The purpose of this post is not to discuss the costs in any detail but I would suggest a perusal of the links cited above. Instead I wish to make some more general observations and clarify certain matters in this regard.

To begin with it is not as if all water supplies would be met from desalted water. Only incremental supplies will be. So if say, 10 % of water is to be met from desalination and it costs 5 times as much as conventional water overall total costs go up only 50 % and don’t become 5 times. (A scenario analysis using various assumptions on the cost of desalting water and its contribution to overall water supplies is encouraged)

However, comparing the marginal cost of desalted water with the average of conventional is not the right way to go about it. Marginal costs ought to be compared with the marginal cost of conventional water supplied. Since the latter is likely to be closer to Rs. 50 and not Rs.10 or so the difference between the two sources narrows down considerably. (The average cost of the RO is nearly the same as its marginal cost).

In short, desalination may be cheaper, relatively, than what appears at first glance.

It is also argued that the energy costs of RO are considerable but that is already included in the higher costs of desalting water and highlighting them separately is wrong and if done unthinkingly may end up in double counting.

Note, that as a practical matter residents of Chennai and industries around the city already pay Rs. 50 or more per cubic metre, the very high end of the cost of desalted water. And if one adds the opportunity cost of time, disease, additional investments in pumps and storage, desalination is not more expensive, probably a cheaper alternative. The extra burden, assuming all costs are to be recovered from users would hardly burn a hole in the pockets of the residents. Compare the monthly expenditure on water with items such as telephony or entertainment. (Tamil Nadu seems rich enough for its government to give free colour TV sets to the needy!!)

The other major concerns with desalination are its environmental impact.

One of them is the loss of marine life during the intake as organisms get sucked in and die. This is rather a minor problem to solve and is preventable by the suitable placement of intake pipes, meshes and beach-wells.

The major worry has been the effluents generated during purification. Note, however, that the common notion that hot water generated during the process can damage the marine ecosystem is not true. Hot water is not generated during RO but brine (highly concentrated salt solution) definitely is.

It has been argued that brine can be discharged at appropriate places and diluted with water to lessen its impact. Another suggestion is to solidify the wastes and dispose them in say, abandoned mines or such places.

But the best possible solution would be to sell it. After all salt is a major input for many chemical industries and maybe it can even be made good enough (after treatment) for human consumption. I am reminded about flyash (generated from thermal power plants) and which was such a problem many years ago. Now cement companies clamour to gain access to it to make blended cement. They are willing to pay for it.

It is also curious that papers such as that of the WWF cited above make no discussion of environmental costs of existing water supplies. After all costs are relative. Groundwater depletion, energy use by borewells, tankers plying all over the city, water transported over long distances, are all environmental costs associated with conventional supplies.

Overall it seems that desalination of water has a promising role to play. It ought to begin small but if economic and environmental costs are reasonable it can be expanded to more locations, and water conveyed inland.

Finally, desalination is not a substitute for demand-side measures. It is sometimes argued that we should rely on the latter rather than the former to solve our problems. Of curse, we should. But where supplies need to be augmented, desalting would be as good a bet as withdrawing water from the ground or bringing it from distant places. Nor is desalination likely to be relevant for the whole of India. It is also not a panacea for the myriad ills of India’s water system but it could play a considerable role in supplying clean water to select locations at low rates with minimal damage to the ecosystem.

Monday, September 10, 2007

Elementary Errors in Analysing Water

Water analysis usually starts with estimates of water availability. According to India’s Central Water Commission:

"Precipitation (including snowfall) is the source of all water on the earth. The average annual precipitation over the country is estimated at 4000 BCM of which a part goes towards increasing ground water storage, a part is lost as evapo-transpiration and the remaining appears as surface water. The water resources potential of the country which occurs as natural run off in the rivers is estimated as about 1869 BCM, considering both surface and ground water as one system. Due to various constraints of topography, uneven distribution of resource over space and time, and geographic [sic] only about 1122 BCM of the total potential can be put to beneficial use, 690 BCM through surface water resources and 432 BCM by ground water."(pg. 13)

These numbers are widely used (see CSE and Iyer (2007)) and rather uncritically.

Note that just over 25 % of the precipitation is estimated of being put to beneficial use. So even a small increase in the utilisation percentage can lead to a big jump in available water.

The paragraph quoted above, however, is factually inaccurate, misleading and incomplete. To begin with the statement about precipitation being the source of all water is erroneous as oceans (97%), glaciers and polar icecaps (2.4%) hold the bulk of surface water. See here. Shallow and deep aquifers (in the aggregate) hold enormous quantities of freshwater.

The CWC statement can perhaps be re-read to indicate an estimate of sustainable water availability as water from rains is replenished every year. However, even so their estimate is incorrect, as we will see below.

Firstly, rainwater which seeps in to the ground is also (potentially) available for use so it should not be deducted from total precipitation. Secondly, India has commitments to supply (let water flow) to neighbouring countries and in turn it receives water from outside its boundaries. The net figure has to be deducted from overall precipitation. Finally, flow of water in rivers and out in to the seas serves many critical ecological and socio-economic functions, so even if all water could be captured and stored one wouldn’t do so.

So beginning with the annual precipitation over the country, a proper analysis must deduct the quantity of evapo-transpiration (strictly speaking this is the only quantity not available for use) and India’s net commitments to neighbouring countries. Water, which needs to flow to the seas to fulfil ecological and other functions, too needs to be subtracted.

Potentially all other water is available for use. However, it is not quite practicable to store all the water that falls as precipitation and much of it flows to the seas. The storable potential is not fixed and has and can be increased. Note, however, that this increase in storage capacity doesn’t necessarily have to come from the construction of large dams. Small storage structures and increasing ground water storage through increase in percolation of rainwater through the soil, to name just two measures, can be just as effective.

Even this analysis is incomplete. For water can be and is used again and again. This is true of the three major water-using sectors – domestic, agricultural and industrial. Return flows, as they are termed are extremely important and the bulk of water used is returned back to the hydrological cycle. Most of this happens naturally but can be enhanced by human efforts. A multiplier is at work here and recycled and reused water may increase manifold the effective utilisable water.

For an extremely illuminating discussion on the above see IWMI especially the section on Water Balance Analysis and Appendix A.

Finally, water supplies can be augmented by desalination of seawater. This is, of course, limited to coastal location and largely for industrial and domestic use but with a coastline of 7,500 kms this need not be a trivial source of supply. Such water is now available at very competitive rates without severe environmental damage (this is not the place to go into details, but I will discuss this in a later post). And rather than take out all the water from our rivers it may be far more sensible to let water flow into the seas and then desalt it.

The CWC analysis (which forms the basis for many others) seriously underestimates water availability in the country. I don’t have the model or the data to estimate the revised numbers but they must surely be much more than present CWC estimates.

{Note: BCM is billion cubic metres. I cubic metre = 1,000 litres. India’s average annual rainfall is 1200 mm (1.2 mts) and multiplied by the area of 328 million hectares gives an approximate figure of 4,000 BCM since a hectare = 10,000 sq. mts. Also 4,000 BCM=400 million hectare metres=4,000 cubic kms.}

Monday, September 3, 2007

Bhopal Revisited

S Ravi Rajan who has written extensively on Bhopal calls it a “natural laboratory” which allows one to study and understand matters such as environmental and societal violence in relation to complex, modern technology (see this essay). In particular, discussing the Bhopal gas leak, which he calls not quite unpredictable or unusual, he states and I quote:

“ …….. Yet, they are far from being freak incidents, results of a stochastic roll of the dice of history.........In light of this history, what happened on December 3, 1984, was clearly not accidental in the sense of a chance, random, unpredictable event......"

The history Ravi Rajan is referring to includes the various accidents at the Bhopal factory of Union Carbide, prior to 1984. This fact juxtaposed with the faulty plant design, departure of skilled staff and manning by under-qualified staff makes his hypothesis seem quite convincing and the accident almost inevitable.

However, closer examination suggests that only is the analysis based on the study of just one major disaster but there is a far more serious problem with it.

It is manifestly wrong (methodologically) to argue backwards from the event after it has occurred. From the knowledge of the disaster having taken place it is simple to trace it to a set of particular circumstances and underlying reasons. It is simple but it is also deeply flawed.

For what of the hundreds of instances where similar initial conditions prevailed but no accident/disaster took place?

To understand this better it is instructive to invoke the ideas of Nassim N Taleb discussed in his book The Black Swan (this is definitely the must read book of 2007 - irrespective of your interests or background. The present analysis owes a lot to this book. If unfamiliar with his ideas see 1 and 2).

A Black Swan event has three characteristics:

  1. small probability of occurrence
  2. large impact
  3. and, retrospective predictability.

As we have seen in an earlier post the Bhopal gas leakage of 1984 was an extremely rare event with huge impact. And yet with perfect hindsight it is rationalised and explained as something not unusual or unpredictable.

However, a proper analysis ought to start with a universe of factories (or a subset of them where the pre-conditions/indicators that have been identified -– small accidents, lack of preparedness, staff issues – are present) and see how many lead to extremely, serious and huge accidents. This would help test if the hypothesis has any predictive power.

In other words rather than start from Bhopal (a known disaster site) one ought to start from factories and move forward. The analysis as done by Ravi Rajan starts with the disaster and then moves backwards to underlying causes and is thereby flawed.

A similar analysis applies in case of the warnings about the hazards from the Bhopal factory and which were largely ignored. Such warnings were and continue to be made in the case of numerous other factories; warnings which were and have been ignored by and large. But the consequences too have never materialised. Even environmentalists didn’t take the warnings seriously till the gas leakage took place in Bhopal.

So should the solitary Bhopal catastrophe lead one to conclude that the other disaster-free plants had appropriate designs, trained staff and high level of preparedness? If so it would make Bhopal even more of an outlier but more importantly it would defy all what is generally known and accepted about the conditions in Indian factories – certainly till the 1980s.

Or alternatively if the plants were not designed safely, had staffing issues and a history of small accidents then the hypothesis as propounded by S Ravi Rajan is faulty since in such factories (with certain pre-conditions identified) no major accident took place. These indicators, it would seem are poor predictors of industrial accidents and Bhopal would be unusual and unpredictable, contrary to Rajan’s thesis.

This still begs the question: what turns some to be Black Swans?

Well, the short answer is that we don’t know; nor can we know prospectively else they wouldn’t be Black Swans.

Think 9/11. In retrospect it is all too clear. But what seems predictable now was inconceivable back then.

It is also very likely that industries have learnt from Bhopal and other disasters and taken steps to avoid them. We will never hear or read about disasters avoided since they never happened!

More Black Swans?

Black Swans are rare but they do occur – though not exactly in the same way. History rhymes, it doesn’t repeat.

It is a frightening thought that though they can’t be predicted disasters will occur and perhaps with extremely devastating consequences.

Should we be worried? Yes. Can we act to stop them? No, and for reasons outlined above.

However, while we all seem to be fixated on low probability events with huge consequences we tend to ignore the more probable ones with smaller distributed impacts.

So while we focus on Bhopal, we ignore the everyday small accidents in factories. We worry about airplane crashes (though adjusted for passenger kilometres air travel may be safer than road travel) while everyday 250 persons die in road accidents in India. To put that number in perspective it is nearly 100,000 people every year. While we are concerned about terrorism (less than 5,000 deaths every year on average in India), millions of infants will not see their first birthday and tens of thousands of women die in childbirth every year.

Not only do these seemingly small matters have more bearing on our lives but they are also far more but amenable to corrective action.

(this post may be read along with the one below)

Rethinking Industrial Disasters

Given the concern that industrial disasters invoke the Wikipedia entry on them turns out to have surprisingly few entries. An Internet search too doesn’t generate many unique entries. Another website has very few industrial disasters listed as happening in the past 50 years. Admittedly these lists are not exhaustive (and they largely omit the plant-level accidents in the former USSR, China and Eastern Europe) but nevertheless it is unlikely that a major disaster affecting the general public would have been excluded.

The list includes several infamous accidents such as Bhopal (undeniably the world’s worst ever industrial disaster), Chernobyl, Seveso and Minamata. Three Mile Island is not even mentioned on the Wikipedia list, presumably due to lack of mortalities, though it crops up frequently in public discussions. See the Wikipedia links cited above for information on fatalities from accidents.

At this stage it is useful to distinguish between several kinds of accidents/disasters.

Bhopal and Chernobyl are examples of (one-time) accidents that had an immediate (and also long-term) massive impact which extended well beyond the plant premises. In the second category are accidents where the impact is confined to the plant premises.

The word disaster is also sometimes used for damage due to pollution (discharge of effluents on a near-regular basis) and which has long-term impacts outside the plant - e.g. - Minamata. It is also used, though less frequently for occupational hazards in work places due to dangerous practices and exposure to toxins.

These four categories differ in origin, causes and their impacts and consequences. Colloquially the word disaster refers to the first category though perhaps the big plant-level accidents too ought to be considered as disasters especially the mining accidents which historically and presently continue to take a heavy toll of human life.

It is because of the immediate and huge consequences that we remember Bhopal and not the other smaller accidents. It is by no means certain that accidents (within and outside plants) cause the bulk or majority of the fatalities. Long-term exposure to toxins among workers and adverse health consequences due to exposure to pollutants among public have grave health consequences and in the aggregate they may match or exceed the fatalities due to accidents.

Industrial disasters which affect the general public grab headlines and comprise most of the discussion on the subject, the horrible consequences of other events notwithstanding. It is not only in popular press that they dominate. Consider for example, the year 2007 publication, Environmental Issues in India, edited by Mahesh Rangarajan. While otherwise very comprehensive in its treatment of subjects it has practically nothing on pollution, occupational health and plant-level accidents.

As mentioned earlier it seems that industrial accidents/disasters affecting the public have mercifully been very rare though it may seem otherwise given the attention that they receive in public discussions.

The rarity of accidents is also somewhat remarkable given the level and growth of industry and the millions of hours of operations at multiple sites all over the world. The Indian chemical industry (broadly defined to include inorganic and organic chemicals and also petroleum refineries, petrochemical plants, fertilizers and pharmaceuticals) too has grown by leaps and bounds and doesn’t seem to have slowed down since 1984 when the Bhopal accident took place. In fact growth has accelerated in the past two decades.

Despite the risks, growth has taken place in several countries and across ownership categories - private, public, MNCs and even co-operatives. And while the profit motive is usually blamed for accidents the continuous process chemical plants actually need to run for long, accident-free, uninterrupted stretches to turn in profits. Hence, the desire for profits is well-aligned with the necessity to avoid accidents and plant shutdowns.

(In the next post I will look at the Bhopal gas leakage)