Monsoon—it’s officially here!

Yes, the monsoon has arrived! Even in the mainland peninsular India!

… Yes, even the government says so, now! [^].


The news was expected for quite some time, may be a week or so by now. … I have been tracking not just the IMD but also SkyMetWeather [^], and in fact, also the blogging by the latter’s CEO. Here is the latest from him [^].

As to the IMD, well, none at IMD blogs. … But still, you have to give them some credit. One would have thought that they would wait for Modi’s address to the joint session of the US Congress to get over before “notorizing” the arrival of the monsoon. … No, the quoted phrase is not mine; it comes from a blog post by Jatin Singh, the CEO of SkyMetWeather. [Sorry, can’t locate that post of his so readily; will insert the link later, if I get it.] That post by Singh had appeared about a week ago, and the author had rightly shown in it why and how the arrival of the Monsoon could be announced right back then—a week ago. … Anyway, apparently, in forming the subjective judgment of the objective criteria [once again, the characterization comes from Jatin Singh], the IMD, it seems, followed the rains more than the PM.

All the same, it’s a huge (and hugely welcome) a piece of news.

… If you are an American (or come from any advanced country) you just cannot in your entire lifetime imagine just what the phrase “Monsoon arrival” means to an Indian.


Yes, I am an Indian. Naturally, my memory (and/or attention-span) is short. Naturally, I’ve already forgotten how fast I had consumed my Internet data-pack limit last month (as was mentioned in my last post). The fact of the matter is, the data pack got renewed just a few days ago. And that’s all that matters to me, right now.

Naturally, I have watched quite a few satellite animation videos, and in fact also want to strongly recommend that you, too, go and watch them. Check out here [^] and here [^]. (As to the EuMetSat site, I have no idea why they have a blank atmosphere on 7th June until about 20:00 UTC.)

For the same reason—of being an Indian all the way to my core—I do not, and would never ever in my life, associate any of the following with the word “monsoon”:

  • Random interruptions in the electricity supply (in the cities where there at all is an electricity supply)
  • Overflowing gutters, drainages, nullahs and minor rivers in the cities; also the blocked roads, the broken down buses, the cancelled trains
  • News of people in the cities being evacuated, but only after a few have already drowned because of the “sudden” increase in the water levels in the areas down-stream of dams, because of a “sudden” and very heavy downpour, even though every one owns a cell phone these days, including those in the slums in the cities and the villages in the rural areas.
  • News of bus getting washed away in the floods in the rural areas because the driver thought that the waters overflowing on the low-lying bridge was not deep enough or fast enough
  • News of young, educated, sleek people from Mumbai and Pune (including those employed in the IT industry, including young women) drowning at Alibag or Murud or Ganapati Pule beach, despite the local people urging them again and again not to go swimming in the seas at a time they themselves don’t dare doing so, because the sea is so rough
  • News of young, educated, sleek people from Pune and Mumbai (including those employed in the IT industry, including young women) drowning at the Bushy dam at Lonavala, despite police yelling at them, using even loudspeakers, not to go and play in the rough waters
  • And, oh, yes, add the Bhandardara lake near Nasik too.  Also the waterfalls near Mahabaleshwar. …

Yes, you have to be an Indian to have this kind of a sense of “humour,” too.

… Yes, we Indians are like that only.

… If we weren’t, life would immediately become far too depressing for even us to handle.


But, any way, we the Indians really feel good when we see the kind of reception our PM receives abroad.

… All of us do. Including those of us in the S. F. Bay Area. (Including those who have become American citizens.) It’s one of those few, few things which makes our lives acquire some luminosity, some rich splashes of the rainbow hues, even if only temporarily. Life becomes interesting then. Magnificent. Majestic. We feel proud then. … We can. Yes, we can. We can feel proud. At such moments.

Our movie-makers know all about it, all too well—the feel good factor. Not just the Hindi cinema, but, now-a-days, also the Marathi cinema.

The Marathi cinema, too, has by now become technically rich. And sleek. As sleek as those young crowds who must flock to the Sinhgad fort on their super-macho motorbikes (or in their massive SUVs) on every week-end during the Monsoons, despite knowing very well in advance that all roads to and near Sinhgad would be overflowing with vehicles, resulting in 5+ hours of traffic jams.

Hey, every one needs to feel better, at  least once in a while, OK?

OK. So, let me, too, join them all, and share a recent Marathi movie song with you.


A Song I Like:

Regardless of what all I wrote above, I actually like this song.

About this song: There is something a bit strange about this song. … Sometimes, a song excels in only a few departments: great tune, great voice, great singing, great orchestration, great acting, great-looking actors, great location, great picturization, or just a great overall theme. Etc. This song is strange in the sense that it is good on many such counts—when the factors are taken individually. The thing is: There is no complete integration of these elements. That’s the strange part about this song… I mean to say, for example, that the words mention rains, but the picturization doesn’t show any. The words, phrases and even metaphors are authentic (even traditional) Marathi, but the orchestration is Western. Etc. And even then, even if a complete consistency is not there, the song, somehow, comes out good. That’s strange.

Anyway, it indeed is a good song. (It certainly is better integrated than the movie in which it appears.) And, yes, I like it.

[As you must have guessed by now, yes, for this time round, I do mean to refer not just the audio, but also to the video of this song. [Yes, I realized that I have the bandwidth to go watch it right now, and that’s all that mattered to me, right now. … Remember, I am an Indian?]]

Anyway, here is the song:

(Marathi) “kadhee too, rimjhim zaraNaari barasaat…”
Lyrics: Shrirang Godbole
Singer: Hrishikesh Ranade
Music: Avinash-Vishwajeet

[Perhaps a minor editing pass may be done 2–3 days later. [Done, right away.]  … My stint at the previous college got over in late-April, and so, these days, I am busy applying for jobs, attending interviews and all. … The research has taken a back-seat for the time being. Implication: I will be busy attending interviews or traveling in the near future, and so, it may be 2–3 days (perhaps 3–4 days) before I am able to come back and think of improving this blog post or check the comments queue here. … But then, probably, even minor editing isn’t required for this post anyway; so regard this version as more or less the final version. [Yes, that’s right. The editing is now done.] … Take care and bye for now.]

[E&OE]

 

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]

Summer, boredom, city skyline, etc.

Boredom. That’s what my life has become of late. … Boredom. … Pure boredom.

Life is boring.

Nothing interests me. Don’t feel like writing anything.

No, it’s not called a writer’s block. To have a writer’s block, first you need to be a writer. And my problem is that I don’t even want to be a writer. Not even just a plain reader. Both are boring propositions.

Life, somehow, has become boring to that great an extent.

Summers always do that to me.


While at IIT Madras, we (a few friends of mine and I) had begun using a special term for that: (Sanskrit) “glaani.”

Usage pattern:

“Did you work out those lab calculations?”

“.” [No answer from me.]

“Ajit, did you complete those lab calculations?”

“.” [No answer.]

“Machchaa…”

“.” [Still no answer.]

The fellow turns around, lethargically. [He, too, doesn’t have much energy left to pursue anything; the heat has been that bad…] … Begins to drag his feet back to his room.

“glaani.” [One attempts some answer, some explanation.]

The fellow does not even care to look back.

The use-case scenario is over.

Currently, it’s summer time, and this year in particular, I am finding it even more lethargy-inducing and boring than it usually is…


Here is an idea I had. I wanted to expand it in a blog post. But since everything has become so summer-ly boring, I am not going to do that. Instead, I will just mention the idea, and let it go at that.

How do you visually estimate the water requirements of a human settlement, say, a city? Say a city with skyscrapers, like Mumbai? (Skyscrapers? In Mumbai? OK, let’s agree to call them that.)

Start with a decent estimate of per capita water requirement. Something like, say, 135 liters/day/person. That is, 1.35 \times 10^2 \times 10^{-3} = 1.35 \times 10^{-1} cubic meters. For one year, it translates to 0.135 \times 365 = 49.275 \approx 50 cubic meters.

An average room in an average apartment is about 10 feet X 12 feet. With a standard height of 10 feet, its volume, in cubic meters, is: 3.048 \times 3.6576 \times 3.048 = 33.98 \approx 35 cubic meters.

Of course, 135 liters/day is an estimate on a slightly higher side; if what I recall is right, the planning estimates range from even as low as 50 liters/day/person. So, taking a somewhat lower estimate for the daily per capita requirement (figure out exactly how much), you basically arrive at this neat nugget:

Think of one apartment room, full of water. That much volume each person needs, for the entire year.

If one person lives in one room (or if a family of four people lives in a 2BHK apartment), then the volume of that apartment is their yearly water requirement.

Hardly surprising. In the traditional water-harvesting in Rajasthan, they would have single-storied houses, and roughly the same volume for an underground reservoir of water. Last year, I blogged quite a bit about water resources and water conservation; check out tags like “water resources” [^].

So, the next time you look at a city skyline, mentally invert it: imagine a dam-valley that is just as deep as the skyline’s height, containing water for that skyline. That would be the residential water requirement of that city.

Of course, if the population density is greater, if one apartment room accommodates 2, 3 (or even more number of) people (as is the common in Mumbai), then the visualization fails. I mean to say: You then have to imagine a deeper (or wider) dam valley.

… I used to be skeptical of residential water harvesting schemes. I used to think that it was a typical NGO type of day-dreaming, not backed up by hard data. I used to think that even if every 3-story apartment building covered its entire plot area (and not just the built-up area) with a 1 to 2 story-deep tank beneath it, it wouldn’t last for even a couple of months. But when I did the actual calculations (as above), I became convinced of the utility of the residential water harvesting schemes—if the storage is big enough.


Of course, as one often hears these days, if common people are going to look after everything from electricity (portable gen-sets, batteries and inverters), water (residential water harvesting), garbage (composting in the house/terrace garden), even security (gated communities with privately paid watchmen), then what the hell is the government for?

If your anger has subsided, realize that only the last (security) falls under the proper functions of government; the rest should actually be services rendered by private businesses. And if government gets out of every thing but the defense, the police and the courts, the economic progress would so humongous that none would bother reading or writing blog posts on residential water conservation schemes—there would be very competent businesses with private dams and private canals to deliver you clean water very cheaply (also via private trains, if the need be)… But then, I am not going to write about it.  Writing is boring. Life is boring. …. So, just look up Ayn Rand if you want, OK?

… Yawns. Life is boring.

BTW, did you notice that boring also means digging, and I was somehow talking about inverting the skyline, i.e., imagining wells and valleys. Kindaa double meaning, the word “boring” happens to have, and I happen to have used it in both senses, haven’t I?

Oh well. But really, really speaking, I meant it only in the simplest, most basic sense.

Life is boring. … Yawns….

[E&OE]