Jala Vijnana (जलविज्ञानम्)

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Jala vijnana (Samskrit: जलविज्ञानम्) is the science of water, referred to as Hydrology in modern parlance. Ancient samskrit literature contains the most valuable and highly advanced scientific discourses on hydroscience, sadly unexplored to a great extent.

In vedas one can find references to the concept of loosely bound water molecules; Puranas mention that water is not created or destroyed and it undergoes a change of state through the various phases of water cycle. Earliest references to the process of raindrop formation, rainfall patterns, astronomical factors that affect rains, the chemical aspects such as evaporation, condensation, cloud formation, precipitation are all found interspersed in ancient texts, showcasing the technological advancement of Bharatavarsha.

Effects of Yajnas (in causing rains), forests, reservoirs, classification of clouds, their color, rainfall capacity etc, forecasting of rainfall on the basis of natural phenomena like color of the sky, clouds; wind direction, lightening, and the activities of animals was well developed in ancient days. Varshamapana yantra (rain guage) a contrivance to measure rainfall was referred in Arthashastra of Kautilya and Ashtadhyayi of Panini. The modern hydrology evaluations are based on the ancient technology used in such yantras differing in the weight measure (of Drona and Pala) instead of the modern linear measurement of rainfall. The quantity of rainfall in various parts of Bharat was also predicted by Kautilya.

Brhat samhita discusses the ground water development and water quality methods. Driven by sound concepts, people of ancient Bharat could locate groundwater, analyze its distribution and had knowledge of reaching these water-tables to irrigate fields.

Water Formations

Hydrology involves the study of flowing water bodies, change of water states and other elements of hydrology and water resources as follows

• Hydrologic Cycle
• Precipitation, cloud formation, measurement etc.
• Interception and Infiltration
• Stream flow and Geomorphology
• Ground Water
• Evapotranspiration
• Water Quality
• Water use and conservation.

Water Cycle

The Hydrological or Water Cycle is an important concept in hydroscience. It is the chain of events describing the movement of water involving the total earth system comprising the atmosphere (the gaseous enveiop), the hydrosphere (surface and subsurface water), lithosphere (s0118 & rocks), and the biosphere (plants & animals). In one of the three phases (solid, liquid, and vapour) the water passes through these four parts of the earth system.

A number of mantras in the Rigveda support the fact that our ancient rshis and maharshis have thorough knowledge of the water cycle and process.

The present day theories of how the sun-ray's heat up the water, creating the vapors and how hot air rises to form clouds in the upper atmospheric strata are all clearly mentioned in the texts. Watery vapors closer to the earth in combination with sun's rays ascend upwards into the sky forming clouds. The Vaiseshika Sutras by Kanada clearly mention the interactions of these particles

नाड्या वायुसंयोगादारोहणम् । वैशेषिक-५,२.५ ।

नोदनापीडनात् संयुक्तसंयोगाच्च । वैशेषिक-५,२.६ ।

वृक्षाभिसर्पणमित्यदृष्टकारितम् । वैशेषिक-५,२.७ ।

अपां सङ्घातो विलयनं च तेजः संयोगात् । वैशेषिक-५,२.८ ।

तत्र विस्फूर्जतुर्लिङ्गम् । वैशेषिक-५,२.९ ।

वायुसयुक्तास्सूर्यरश्मयः अपः भूमिष्ठास्तावदन्तरिक्षमारोहयन्ति ।। (K. S. 5)

अन्तरिक्षमारूढाः खल्वापः धूमेन ज्योतिषा वायुना च संसृज्यमानाः मेघभावमापद्यन्ते (Form clouds) |

Water rising (in the form of vapor) by combining with the smoke, heat (of the sun's rays) and winds (in the upper strata) form the Clouds. When water and

जले दिव्यज्योतिस्संयोगे सति विद्युत्प्रकाशः (Lightning) ततो विस्फूर्जथुः (Thunder) |

Kalidasa also poetically mentions the formation of clouds in his Meghadoota.

धूमज्योतिस्सलिलमरुता सन्निपातः क्व मेघः । (Megh. 5)