Micro-level water-resources engineering—7: Dealing with the [upcoming] summer

Last monsoon, we’ve mostly had excess rain-fall in most parts of Maharashtra, even over India, taken as a whole.

Though the weather in Maharashtra still is, for the most part, pleasantly cool, the autumn season this year (in India) is about to get over, right this month.

Therefore, right now, i.e. right at the beginning of February, is the perfect time to empirically check the water levels in all those check-dams/farm-ponds you have. … That’s because, evaporation is going to happen at an accelerating pace from now on…

Between end-October (say Diwali) and March (say Holi), every solar year in India, the reduction in the levels of the stored water is dominated by the following two factors:
(i) seepage (i.e. the part which occurs after the rains cease), and
(ii) usage (i.e. the irrigation for the “rabbi” (i.e. the winter agricultural) season).

But from now on, the dominant factor is going to be the third one, namely, (iii) evaporation, and it is going to be increasingly ever more important throughout the upcoming summer, i.e., until the arrival of the next monsoon.

As I had earlier pointed out in this series  [^][^], in Maharashtra, the losses due to evaporation are expected to be about 5–8 feet (or 1 to 1.5 “puruSh”) deep.

Don’t take my word for it. … Go out and actually check it out. (Take snap-shots for your own record, if you wish.)

The beginning of February is also the perfect time to start executing on your plans for any maintenance- or new construction-activities on any check-dams/farm-ponds/residential water conservation that you might have thought of, in your mind. If you start executing on it now, you still have a very realistic framework of about 4–4.5 months left, before the next monsoon rains are slated to arrive [give or take about a half month here or there].

…Just a reminder, that’s all.


Keep in touch, best, and bye for now…


[As usual, I may come back and edit this post a bit after its publication, say, after a couple of days or so… I don’t know why, but things like that—viz., thinking about what I did happen to write, always happen to me. But the editing wouldn’t be too much. … OK. … Bye [really] for now.]

 

Micro-level water-resources engineering—6: Evaporation

As compared to the last year, public awareness about water resources has certainly increased this year. It has been a second drought-year straight in a row. None can miss it—the water issue—now. [Not even the breweries.]

There are several NGO initiatives involved in the awareness campaigns, as always. Even celebrities, now. Also politicians.

The heartening part this year is that there also is now a much greater participation of the common people.

Indeed, water conservation schemes are these days receiving quite a broad-based support, cutting across all political party-lines. People are actively getting into the building nallah-bunds, farm-ponds, and all. Good.

Good? … This is India, so how can anything be so straight-forwardly good?

With that question mark, I began taking a second look at this entire scene. It all occurred to me during a show that I saw on TV last week or so.

Well, that way, I don’t watch TV much. At least in India, TV has gone beyond being a stupor- or passivity-inducing device; it has become an active noise generator. So, the most I can put up with is only some channel-flipping, once in a while. [In my case it is typically limited to less than 15 minutes at a time, less than 7 times a week]. In one such episode [of flipping through the channels], I happened to catch a few minutes of a chat that some Marathi journos were having with Aamir Khan and Satyajit Bhatkal. [They should have been in awe of Bhatkal, but instead were, of Aamir Khan. [Journos.]]

Both Khan and Bhatkal were being all earnest and also trying to be all reasonable on that show, and in that vein, at one point, Bhatkal mentioned that there have been hundreds (or thousands) of KT-weirs, nallah-bunds and all, which have been implemented by the successive Maharashtra State governments. These are the structures or works which now have become defunct because of a lack of maintenance. Mentioning this point, he then added something like the following: [not his precise words, but as my casual impression of what he effectively was saying]:

For the best or the most optimum utilization of the available money, it would be better to begin with a revival or maintenance (like silt-removal/wall-repairs) of these thousands of the already existing structures, rather than building everything anew, because the latter would cost even more money.

Looks like quite sensible an approach to take, doesn’t it?

Well, yes, on the face of it. But not so, once you begin to think like an engineer about it. In fact, I do want to raise one flag here—one very big, red flag. [No, I am not a communist, just in case you have begun reading this blog only now.]

Let’s look at some hard facts—and also some simplest physical principles—first.


The only primary source of water is: the rainfall.

The two means of conserving water are: (i) surface storage, and (ii) ground-water recharge.

The two big [physical] enemies of water conservation are: (i) run-off and (ii) evaporation.

Run-off means: Rain-water running off the earth’s surface as floods (may be as flash-floods), without getting intercepted or stored anywhere. Evaporation means: the loss of the stored water due to ambient heat.

It’s good that people have gotten aware about the first part—the runoff factor. The by-now popular Marathi slogan: “paaNee aDavaa, paaNee jirawaa” [English: “block water, percolate water”] refers to this first factor. Unfortunately, it has come to refer to only the first factor.

People must also become fully aware about the second factor—namely, evaporation. It too is just as important in India, particularly in places like Maharashtra.

Evaporation is not always an acute concern in the cooler climates (think USA, Canada, Europe, Japan, Australia, New Zealand). But it is, in the hotter climates (think most of the third world). My focus is exclusively on India, mostly on Maharashtra. Since most of the advanced countries happen to lie in the cooler regions, and since in India we habitually borrow our engineering common-sense from the advanced countries rather than developing it individually here, I want to once again stress this point in this series.


As I mentioned in my last post in this series [^]:

“Evaporation is a really bad factor in hot climates like India. At the level of large-scale dams and even for check dams, there is precious little that can be done about it.”

There is a technological reason behind it: You can’t sprinkle some powder or so to cover the surface of a water body, and thereby arrest or slow down the evaporation losses, without also polluting water body in the process.

These days, you often see a layer of water hyacinth in dams/rivers. Thought the plant contiguously covers the water body, contrary to the naive expectation, it in fact accelerates evaporation. The plant sucks water from below and perspires it out via leaves. This rate of perspiration happens to be higher than that of the plain evaporation. Further, water hyacinth has big leaves. The total surface area of the leaves is many times greater than the area of the water body that the plant covers.

But, yes, the simple-minded idea is right, in a way. If instead of the water-sucking water-hyacinth, something else—something chemically inert and opaque—were to cover the water body, then it would cut down on the evaporation losses. People have tried finding such a material, but without success. Any suggested solutions are either not scalable, not economical, or both. That’s why, evaporation is a fact that we must simply learn to live with.


Let me continue quoting from my aforementioned post:

“Evaporation maps for Maharashtra show losses as high as 1.5 m to even 2.5 m per year. Thus, if you build a check-dam with a 3 m high wall, expect to lose more than half of the [stored] water to evaporation alone.

For the same reason of evaporation, most nallah-bunding and contour-trenching works [such as] those typically undertaken under the socialist programs like MNREGA don’t translate to anything at all for storage, or for that matter, even for seepage. Typically, the bunds are less than 1 m tall, and theoretically, water in them is expected to plain evaporate out right before December. Practically, that anyway is the observation! […] It is a waste of money and effort.”

That’s what I had said, about a year ago. It needs to be repeated.

Most people currently enthusiastic about water conservation simply don’t seem to have any appreciation as to how huge (and how hugely relevant) this factor of evaporation is. Hence this post.


To repeat: In Maharashtra, the range of evaporation losses is as high as 1.5–2.5 m. That is, about 5–8 feet, in terms of the height of water lost.

Thus, if you build or repair a nullah-bund that is about 10 feet tall (which is the typical height of a house), then you should expect to lose about 75% of the stored water to evaporation alone. Perhaps even 90% or more. After all, nullahs and rivers typically have a progressively smaller width as we go deeper, and so, the volume of the water body remaining at the bottom after evaporation is even smaller than what a simple height-based calculation tells you.

Coming back to the Khans and Bhatkals, and Patekars and Anaspures: If the small check-dam or Kolhapur-type of bund/weir you are repairing this summer is, say, 7–8 feet high, then what you should expect to see in the next March or April is: a dry river-bed with a few puddles of water perhaps still lingering here and there. Picture a stray dog trying to satisfy his thirst from a puddle that is relatively cleaner from among them, but with a vast patch of a darkish brown, rocky or parched land filling the rest of your visual field. In no case should you picture a large body of clean water extending a couple of kilometers or more upstream of the bund. The fallen rain-water would have got blocked by that bund, sure, but if your bund is only 7–8 feet tall, then all of it would have disappeared [literally] in the thin air through evaporation alone, by the time the summer arrives. [We are not even counting seepage here. And realize, not all seepage goes towards meaningful groundwater recharge. More on it, may be, later.]

Now, the fact of the matter is, many, many KT weirs and bunds, as built in Maharashtra, are hardly even 5–6 feet tall. (Some are as low as just 3–4 feet tall.) They are, thus, not even one (Marathi/Sanskrit word) “puruSh” deep. …

The next time you go for an outing, keep an eye for the bunds. For instance, if you are in Pune, take an excursion in the nearby Purandar taluka, and check out the series of the bunds built by the PWD/Irrigation department on the Neera river. Most of them are just 3–5 feet tall. None is as big as a “puruSh” tall. None ever shows any water left after December. [But don’t therefore go and talk to the PWD/Irrigation engineers about it. These engineers are smart. They will tell you that those are flood-control structures, not water-storage structures. You will thus come back non-plussed. You are warned.]

… In case you didn’t know what “puruSh” means: Well, it’s a traditionally used unit of depth/height in India. It is defined as the uppermost reach of a man when he stands upright and stretches his arms up. Thus, one “puruSh” is about 7–8 feet. Typically, in earlier times, the unit would be used for measuring the depth of a well. [During my childhood, I would often hear people using it. People in the rural areas still continue using it.]

So keep the following capsule in mind.

In most parts of Maharashtra, expect the evaporation losses to be about one “puruSh” deep.

If the water-body at a nallah-bund/check-dam/farm-pond is one “puruSh” deep during the monsoon, then expect its water body to completely dry up by the time the summer arrives the next year.

Therefore, an urgent word of advice:

If you are building farm-ponds or undertaking repairs of any bunds or KT weirs structures this year, then drop from your planning all those sites whose walls are not at least 2.0 “puruSh” tall. [If a wall is 2.0 purush tall, the water body will be about 1.5 purush deep.] Evaporation losses will make sure that your social-work/activity would be a complete waste of money. The successive governments—not just politicians but also social workers, planners, bureaucrats and engineers—have already wasted money on them. Let the wastage stop at least now. Focus from now on only on the viable sites—the sites where the depth of the water-body would be at least 12–15 feet or so.

If the nullah is not naturally deep, and if the local soil type is right, then you may think of deepening it (to a sufficient minimum depth), perhaps with machinery and all.

But in any case, keep the factor of evaporation in mind.


As pointed out in my earlier posts in this series, given the geological type of the top layers in most parts of Maharashtra, seepage is not a favorable option for water conservation planning.

The only exception is the patch that runs across Dhule, Jalgaon through Wardha, Nagpur. There, the top-layer is sufficiently sandy (as in Rajasthan.) Mr. Suresh Khanapurkar has done a lot of seepage-related work in this patch, and groundwater recharge indeed is a viable option there.

But remember: seepage is not viable for most of the remaining parts of Maharashtra (and in fact, it also is not, over very large patches of India). So, if your idea is to build shallower bunds with the expectation that it would help improve groundwater levels via seepage during and soon after monsoon (i.e., before evaporation kicks in the months following the monsoon), then that idea is not so much on the target, as far as Maharashtra is concerned. Engineering for seepage can be viable only if the local geology favors it.

For the general-purpose water conservation, in most parts of Maharashtra, we have to look for storage, not seepage. Therefore, evaporation becomes a more important factor. So, avoid all shallower sites.

In particular, when it comes to farm-ponds, don’t build the shallower ones even if government gives you subsidy for building them (including for the blue plastic sheet which they use in the farm-ponds to prevent the wasteful seepage). If your pond is shallow, it would once again be a waste of money, pure and simple. Evaporation would make sure of that.

That’s all for now, folks.


Yes, I have been repetitive. I don’t mind. I want to be repetitive, until the time that social workers and engineers begin to show a better understanding of the engineering issues involved in water conservation, esp. the factor of evaporation. Currently, an appreciation of this factor seems to be non-existent.


My blogging in the upcoming weeks will be sparser, because I have to re-write my CFD course notes and research related notes, simulation programs, etc. I lost them all during my last HDD crash. I want to complete that part first. So excuse me even if I don’t come back for some 3–4 weeks or more for now. I will try to post a brief note or two even if not a blog post, but no promises. [And, yes, I have now begun my weekly backups, and am strictly following the policy—the notifications from the operating system.]

Bye for now.


[May be one more editing pass, later today or tomorrow… Done.]

[E&OE]

It’s Hot…

It’s hot—I mean the weather. I mean that in Pune. I mean the one right now.

The temperatures in the city have consistently been hovering around/above 40 degrees, and this is unusual. That way, it’s possible that the the max. temp. figures themselves might not be very much above the average. It could also be that the min. temp. is way above the normal temp. Or, if not that too, then at least the temp profile throughout the day—the total flux received per day as such—might have gone significantly up. Or, the wind is unusually low… Whatever. But the fact is that it’s been very much hot for the past many days—not just in Pune but also for most of Maharashtra (and other parts of the country). … Hmmm….

…Is it just me, or have our daily newspaper-wallahs from Pune really forgotten to print photographs or news-stories on one or more of the following (listed in no particular order):

  1. Naked urchins caught mid-air on camera while jumping into: (a) Mula, (b) Mutha, (c) Mula-Mutha, or (d) a canal
  2. A vendor of water-melons caught napping on a heap of the fruit at the market-yard, right on the hot afternoon
  3. A sparrow or a crow perched on a municipality water-tap, its neck strenuously bent down towards the outlet of the tap, trying to drink the infrequent droplets of water coming out of the tap
  4. A close-up of a dry river-bed showing that typical criss-cross patterns of cracks developed in the baked mud
  5. A color photograph of a bright-red “gulmohor” tree, say on the NDA road, snapped by some practising general physician (who has not let his finer sensibilities die despite the demands of his profession and his obviously busy schedule (from 10 to 1 and 4:30 to 7:30, this being Pune))
  6. A photo of the fallen levels of water in the dams nearby. Here, two options are available to the newspaper editor: (i) If he likes a long-shot, show the dry contours of the near-empty reservoir. (ii) If he likes a close-up, show the vertical water level-gauge near the dam wall which used to have red and white markings in a previous life-time.
  7. A photo showing the audience in a small meeting hall, the audience consisting solely of working journalists, the photo itself appearing with a caption that the event was organized for discussing P. Sainath’s book: “Everyone Loves a Good Draught”. … Even without reading anything further from the news, it is easy to make out that they all are working journalists, because:
    1. all the males in the audience have beards and no female seems to have any kind of a make-up put on
    2. regardless of their gender, they all: (a) appear in cotton/khaadi “kurtas,” (b) record news the old-fashioned way, by scribing down in a school-student’s notebook, i.e. without using audio/video recorder, (c) carry “shabnam” bags

I don’t think I have seen any one of the above-mentioned news items in any one of our Pune newspapers (including the local editions of the National Newspapers) … Why is it so? Why? Have our H’ble Ministries/Departments of Information and Broadcasting, Environment, Irrigation, Water Supply, Science and Technology, Meteorology, etc. all been sleeping? Shouldn’t they be more careful and see to it that proper news items are punctually published in all our newspapers? … Weren’t the matters soooo much for the better during those BJP years?

..Err… Leaving aside the dark-grey [“nothing is all black or all white”] humor…

…Ok. Really leaving humor aside and getting serious about something that is worth getting serious about:

Here is a reminder that now is the time to execute at full-speed all those micro-level projects like “paaNi aDavaa, paaNi jiravaa.”

… I don’t know if it is true but it’s a widely held belief that if a summer is unusually hot, as this summer seems to be turning into, then the monsoon following it also tends to be more intense. … A greater rain-fall ought to make for good news in a heavily rains-dependent country like India, but, unfortunately, this always is not true—even a greater rain-fall is only a mixed blessing. In India, just the way we waste any other natural resource (including time), we also put to waste most of the water that falls in this land… The way we function, typically, people wake up about the need to put up small dams in their places only in the month of July (just the way we wake up to the need to put up large dams in place only in mid-May).

The time to act to for the next monsoon is now—at least for those micro-level projects.

– – – – –

A Song I Like:

(Marathi) “nav laakh taLapatee, deep vijeche yeth_…”
Lyrics: “kusumaagraj” (V. V. Shirwadkar)
Music: “aNNasaaheb chitaLkar” (C. Ramchandra)
Singer: “aNNasaaheb chitaLkar” (C. Ramchandra)

PS: If someone can locate a record/CD for this particular song, please drop me an email (aj175tp AT yahoo DOT co DOT in). Thanks in advance!

PPS: Now that I have begun writing shorter blog-posts covering only one-two topics (and so long as I continue doing so) I am going to reduce the number of songs listed in this last section—one, at most two.

[To be streamlined at the time of the next post]

A Real Quick Update (11 Oct. 2008)…

OK. I know I have not been blogging for a while… A lot of stuff is lying unorganized in my mind and I need to get it together…. In the meanwhile, here we go in a real quick manner—just the bullets (NASA style)

  • About water resources in India. I am going to point out to a document prepared by a government agency, but cannot somehow find it right now on my local disk. Once I do, I will put my thoughts together. But still, briefly, as far as water management goes, groundwater level in India has been going down rapidly, and is a matter of grave concern already. I think a multi-pronged approach is necessary. While the points raised by Arundhati Roy in an article years back in Times of India were right (she spoke about settlement of soil and subsequent reduction in the capacity of the big dams, for what *technical engineering reasons* increasing heights is not always the solution, how more grainstock gets eaten by rats in FCI godowns than goes to poor people with the result that the government is actually is subsiding rats rather than people, etc.), I still believe there is a necessity to have large dam projects. Actually, it should be a mix of a few large, many medium, and numerous small or micro-level dams. There is no alternative to large dams for flood control, and the concentrated efforts undertaken by several NGOs towards educating the public on “groundwater harvesting” is, actually, a ridiculous idea—it is far too inefficient. Smart way would involve what general Indians (outside the government baboos) are poor at: meticulous records keeping. As my new suggestion, you need to ask all the bore-well drillers to submit records of what kind of rock exists at what location, and then, someone (ideally, a business house like Reliance) should use geographical software at a micro level to identify the best places to build both percolation tanks (numerous at micro scale, low-tech versions of them). With a bore-well at an avarage distance of a few kilometers (and in some locations, crowded further together), you will get a much better 3D map of soil layers and water table in different locations than the best maps government has on them today. It’s the typical dull bureaucratic mindset which has (i) advocated drilling more bore-wells, but essentially anywhere people wanted to, and (ii) not asked for records keeping for the millions of bore-wells already drilled. On the other hand, the NGOs seem to think that there is only one way to counter that kind of dullness, which is, to undertake colorful day dreaming and wishing that wherever in whatever urban areas people do groundwater harvesting, it’s going to be the right place to do so. More on all these topics, later. (But since I have been promising for a long time, I had to give at least an indication of what I had in mind.)
  • About the nuclear deal. I am glad that it has, finally, gone through. “Hushhh…” (That is like the “pheww” in the American, and not like the “shoooo”.) The Americans predictably gave talking points to communists and BJP alike, when they did insert, at the last minute, provisions to the effect that they won’t supply uranium for bombs-making in future (i.e., if India tests). The reason I supported the deal is not that I wish to see a weak India. The reason I supported it is because with this deal, a definite formal way has been put in place with which the two countries could talk on the issues. The BJP+’s idea has been to continue doing what they are best at: aggressive posturing. For instance, read Arun Shourie’s full-page articles in the recent times in Indian Express. (There are many in BJP who are not worth taking intellectual notice of; Shourie is rather in a minority in that party.) But sometime, you have to take a realistic stock of the situation in India and ask yourself, honestly, with all the poor population that India has, how further aggressive and strong can the nation at all get? BJP never did permit this thought to come up anytime during their entire six years’ rule. Their whole idea was simply to evade the issue. If the Americans engaged in pressure tactics, sacrificial men like Ajit Jadhav (me) were handy. (I have read Shourie talk about the kind of follow-up he faced in Indira Gandhi’s rule. My question to him is: Will he face up to me—i.e., face up the description of the kind of follow-up that I have suffered when his party was in the rule? (And it’s not just me—my family suffered too, alongwith me.) And what “guaruntees” can he have to offer that the performance won’t be repeated should his party come in power in the next general elections? On what basis? As to the communists, it was not at all surprising that they would oppose any form of cooperation with the Americans. But what this episode showed us was the essential identity of the basic wordview—defined by collectivism, altruism, mysticism and intrinsicism—which is shared by both the left (communists) and the right (BJP). Congress may only be a “muddle in the middle.” Sure. But compared to these two camps, Congress does, indeed, come out far too better—despite actually being a “muddle”. (Very apt description, that was, though I don’t know where and when I read it first. But I loved the expression… In terms of aptness, it competes with, but still is not as delightful as the “teflon” analogy for “nothing [bad] sticks onto [some politician].”) More on this all—I mean, politics and not communication—later. (I need to explain why I say they share the basic worldview, and how. So far, I have only stated that they do—without any explanation.) Pending work…
  • Incidentally, politics really does not interest me all that much. I have been busy with computational engineering and quantum mechanics. But before I come to it, I also want to note, before I forget to mention, that I think it is high time that Sharad Pawar became prime minister. To my mind, he is eminently well suited for the job. Stronger: He would make an extremely competent PM. But the thing that I wish to really discuss is not the question of why he should become a PM. The more interesting question is: Why has he not already become one? Sharad Pawar’s qualifications for the job are so obvious that the second question is far more interesting than the first one. I plan to discuss it one of these days here. And, no, to my mind, this is neither an affront to Dr. Manmohan Singh, nor a lessening of the admiration that I do have for that gentleman. … It also does not mean I give up my right to criticize Mr. Sharad Pawar’s decision or even some of his policies. … The politics in India has sunk to such low levels that one has to issue such clarifications.  But, anyway, I will certainly write on this topic—the second question—one of these days… Hope to find time, though!
  • And, now, about quantum mechanics.  I do have an announcement about a proposed Study Group for self-studies of QM, already posted at my Web site; see http://www.JadhavResearch.info/training.htm

I will expand these points one by one (in no particular order) as time goes on… But I really don’t find time for blogging as much as I would like to…

PS: The results of the test of astrology, conducted by the “Andhashraddha Nirmulan Samiti,” are out. I had participated in it as an “amateur”—though, as I said here in my blogs earlier, I do not believe in astrology. I do have something to add concerning the nature of the test—it was not a very well designed test, if you ask me. But then, on the other hand, I also have a few further things to add as to why astrology just cannot be a science… More on these things too, later.