I would very much appreciate any information on the following

(1) The earliest mention of a complete/partial understanding of Hydrologic Cycle (Water Cycle) in Hindu scriptures.
(2) The earliest mention of the record of rainfall and other hydro-meteorological data.
(3) Any other information on Hydrology/meteorology in Hindu scriptures.

Thanks.

(3)Any other Information:-(a) "Aakaasath Pathitham thoyam Yadhaa Gacchathi Zaagaram"(I know this is a veda Mantram-reference I do not know)---Akaasath= from the sky---Pathitham=falling down----Thoyam=
Water(in the form of rain/or snow fall)--Yadha=in which way---Gacchathi=goes/travels----and reaches---zaagaram=Ocean.{("Sarva Devam namaskaram Kesavam Pradhigacchathi=same way Salutations to all gods reaches sri.Kesava)}(b) Aapaha punanthu Prthveem----Aapaha=water---Punanthu=Purifies/makes fresh---Prthveem =the earth(I feel the purport is after a good rain, the copious flow of water cleans the earth from filth/dirt/dust etc)----(c) "Yo Apaam Aaya Dhanam veda-Aayadhanavaan Bhavathi"
(Krishna Yajur vedam)--Ya(Yo)=the One---Veda=understands/possesses the knowledge(Hydrologist?!!)---Apaam =water is---Aaya=most gainful/most profitable--- Dhanam=Wealth---that person---Bhavathi= let him/her become---- Aayadhnavaan=the richest person.In my opinion this is the most important vedic rk praising the supremacy of water.In a nut shell it says of all wealth Water is the best wealth

Falling of rain and its flow (on the surface) to ocean is obvious to one and all.

If one knows that the rain clouds originate in the ocean and the flowing back to ocean is not only on the surface but also subsurface, then that would indicate a knowledge of the Hydrologic CYCLE.

When, and whether, ancient Hindus knew that it is a cycle, not a one-way flow from Indradeva (rain) to ocean?

Dear Shri.Jha,
i think the following translated verses of Rigved
may explain a little.
These verses are being put forth in their exact form as printed in the Book"Mysticism in the Rigveda" by Dr.T.G.Mainkar and first published in the Year 1961.

Vashistha address the Waters thus: (in vii 47 &49)
All-purifying,joying in their nature,to paths of Gods the Goddesses move onward.
They never violate the laws of Indra.
Present the oil-rich offerings to the Rivers 47.3

2.Whom Surya with his bright beams has attracted,
and Indra dug the path for them to travel,
May these streams give ample room and freedom 47.4

3.These Waters are bright,purifying,speeding to the Ocean;amid them goes Varuna--- 49.3

my views are:1. the Godesses are the innumerable
streams of water
2.The path of Gods is the rain cycle
3.The incessent charecter of this cycle without undergoing any change is depicted in"never violate the laws of Indra".
4."Present the oil-rich offering to the Rivers"
speaks of knowledge about the sub-surface.
5."Whom Surya with his bright beams has attracted" evidently tells us about the formation of clouds.
6."Indra dug the path for them to travel"
indicates the subsquent rain fall.
7."These Waters are bright,purifying,speeding to the Ocean,amid them goes Varuna--" obviously
clears it further.

The Author of the Book has dealt with Mysticism
under various captions like Rituals,Nature,Beauty-The interpretations, as far as our subject is concerned, are mine and therefore, i owe the entire responsibility of any mis-interpretation.

i,sincerely ,appreciate the idea behind bringing up this topic for discussion and do hope that more and more of Topics like this will be brought
forth to elaborate the Value of our Sacred Literature in various fields.

OM-TAT-SAT

Please see Manu 3.76

I am trying to locate a book "The Story of Creation" by Pundit Bhagavad Datta which details the cycle, numerous vareities of clouds, manifestation of lightening, types of wind etc as discussed clearly in the vast Vedic texts. Will post the stuff as soon as I find it.

Let me see if I could go to the local library, where I have definitely seen several books on this topic.

Regards

Vishal

Many thanks to Dr. SSR, Dr. Ninad and Sri Vishal. I hope to get some more information from so many knowledgeable persons on this forum.

The verse from Manu Smriti suggested by Sri Vishal says

3:76. An oblation duly thrown into the fire, reaches the sun; from the sun comes rain, from rain food, therefrom the living creatures (derive their subsistence).

I am eagerly waiting for more on what Sri Vishal has mentioned.

The Encyclopaedia Britannica says

The idea that the waters of the Earth undergo cyclical motions, changing from seawater to vapour to precipitation and then flowing back to the ocean, is probably older than any of the surviving texts that hint at or frame it explicitly.

The idea of the hydrological cycle developed independently in China as early as the 4th century BC and was explicitly stated in the Lu-shih Ch'un Ch'iu ("The Spring and Autumn [Annals] of Mr. Lu"), written in the 3rd century BC. A circulatory system of a different kind, involving movements of water on a large scale within the Earth, was envisioned by Plato (c. 428-348/347 BC). In one of his two explanations for the origin of rivers and springs, he described the Earth as perforated by passages connecting with Tartarus, a vast subterranean reservoir.

A coherent theory of precipitation is found in the writings of Aristotle. Moisture on the Earth is changed to airy vapour by heat from above. Because it is the nature of heat to rise, the heat in the vapour carries it aloft. When the heat begins to leave the vapour, the vapour turns to water. The formation of water from air produces clouds. Heat remaining in the clouds is further opposed by the cold inherent in the water and is driven away. The cold presses the particles of the cloud closer together, restoring in them the true nature of the element water. Water naturally moves downward, and so it falls from the cloud as raindrops. Snow falls from clouds that have frozen.

In Aristotle's system the four earthly elements were not stable but could change into one another. If air can change to water in the sky, it should also be able to change into water underground.

If Hindus had better knowledge at an earlier date, why shouldn't we send such information to The Encyclopaedia Britannica, and other such popular references.