In this age of economic growth coupled with substantial population increase, more and more regions of the world are finding their water resources quite inadequate. The time is fast approaching, experts opine, when man will not be able to command enough supplies from rivers and groundwater as well, the sources he has been dependent upon since the ages¹. The economic aspect of water conservation and use is a problem to count on its own merit and, of late, it is assuming more importance than ever with the increased multipurpose use of resources and the growing disproportion between ‘demand and supply'. Every wrong step taken in handling the said resources, a move which, at first glance might seem to be economically justified for the given situation, results in sizeable loss over time.   “Let us not”, Engles² says, “however, flatter ourselves over much at our conquests over nature, for each such subjugation takes its revenge on us”.   It is a tangled web we weave and there is really no getting away from the fury of nature when things do not go as they are meant to.   Prognostication will help to find ‘just' solutions to the problems of conserving and using water resources.   Long-range forecasting has enabled us to establish a number of sound and workable principles of water planning, conservation and use.   These principles will determine technological policy in the development of the water economy.

The history of the vast sub-continent of India dates back to over 2500 years B.C. when world civilizations were in their infancy.   The Republic of India is clearly demarcated from the rest of Asia by the 2400 km long Himalayan mountains, the multiple ranges that rise to heights over 20,000 ft, roughly, triangular in shape, tapering to the south and dividing the northern Indian Ocean into the Arabian sea and the Bay of Bengal flanked by the Malabar- and the Coromandal coasts respectively. In the east, the Pokkari hills and the Arakan Yoma form the boundary between India and Myanmar.   South of the Himalayan foothills and forming a huge curve from Ranjitpura – Pugal (Rajasthan) to Kolkatta (WB), is the great Northern- or the Indo-Gangetic Plain.   It is 3328 km long with an average width of 432 km.   It is one of the most fertile plains in the world with thick alluvial soils.   It is so level that the mean gradient along the Ganges is not more than an inch per 2 km.   Within its huge basin of about 4 m.sq.km. live a third of India's population and there are, probably, more farms here than in the rest of India put together.

Peninsular India is a plateau country, occupied by the ‘Deccan plateau' which tilts towards the Bay of Bengal.   The steeper hills which bound the plateau on the west are called the ‘western ghats' and overlook the Arabian sea; while the more gentle slopes on the east are identified as ‘eastern ghats'. The Coastal plains are narrow and intensively cultivated with tropical crops.   The north-western Deccan is made up of lava on account of series of flows ejected by volcanic vents.   The Satpura range forms a line of division between the Northern Indian Plain and Peninsular India.   In the south-west are the Nilgiri and Cardamom hills, the only significant tea-growing area of India outside the Assam hills.

THE BIOTOPES

A.         THE RIVERS OF INDIA:

            The ‘riverine resources of India' comprise of five major river systems namely:-

•  The Ganga system commanding a total length of about 8047 km, is among the largest river systems in the world.   It drains the southern slopes of the Central Himalayas and covers the States of Haryana, Uttara Pradesh, Bihar, West Bengal and parts of Rajasthan and Madhya Pradesh.

•  The Brahmaputra system with a combined length of 4023 km drains the northern slopes of the Central and Eastern Himalayas, Assam, Bhutan, Sikkim and parts of north-west Bengal.

•  The Indus system, though massive as a whole, has only a small segment left in Independent India where the important rivers are the Beas and the Sutlej.

•  The East-coast system in Peninsular India is, infact, a composite system of rivers, the main constituents of which are the Mahanadi, the Godavari, the Krishna and the Cauvery having a combined length of about 6437 km. The system drains the entire peninsular India, east of Western Ghats in the west and the southern parts of Central India including Chota Nagpur hill ranges.

•  The West-coast system in the south drains the narrow belt of Peninsular India, most of western ghats but, further north, it includes the basins of the Narmada and the Tapti and the drainage of Gujarat.   The Narmada and the Tapti are the largest rivers of this system and all the other lotic resources of this region arising from western ghats are short and, though many are perennial, most are like torrential streams only. The length of the rivers of this region is about 3380 km³.

These rivers, inclusive of their tributaries, run approximately to a collective length of 27,359 km, and if the vast network of canals and channels are considered it adds up to about 2,12,654 km^3,4.

The rivers have been of significant importance in the cultural development of man. The habits of men and the forms of their social organisations have been influenced more by their close association with water than with land from where they earn their bread.   At the dawn of civilisation man settled on the banks of rivers, sailed down rivers to explore unknown lands, drank river water and ate fish caught in rivers. As productive forces developed, man began to use river water for irrigation and then as a source of power, from primitive water mills to modern hydro-power plants with capacities of five million kilowatts.

Many ancient civilisations were inseparably bound with rivers – ancient Egypt with the Nile, Assyria and Babylon with the Euphrates and the Tigris and India with the Indus and the Ganges. So also, the history of Russia was closely linked with her rivers – first with the Dnepier and then with the Volga. The St. Lawrance and Mississippi rivers and Great Lakes played a big role in the development of North America, as did the Parana, Paraguay, Uruguay and Amazon rivers in the settlement of South America. Although all of Africa's large rivers have numerous rapids and waterfalls, the Nile, Congo, Zambezi, Orange and other rivers play an important part in the life of the continent.

During the pre-independent era of the country, the flood waters of the rivers used to be drained into the seas. However, during the post-independent period, the ‘Planning Commission' had drawn-up detailed projects for the utilisation of the flood waters by constructing dams. Both the Central and the State Governments now have recognized the need for introducing specific flood control programmes designed to prevent floods. The establishment of the Commission in 1954 to look-after flood control, is doing its best to mitigate the sufferings of men and loss of material wealth.   The Central Water and Power Commission, perhaps, in view of the success achieved in many river valley projects in the country, is keen on 'power schemes'.

In all the rivers of the country, there are marked disparities in the flow regime from year to year and season to season.   Preliminary assessment of surface water resources of India has been computed to be 1.675 mcum which is an estimate of the quantum of water draining through its rivers.   Of this, 0.204 mcum is utilized for irrigation and hydro-power generation.   This proves that hardly 12.0% of the surface flow is utilized in the country⁵.

B.         THE RESERVOIRS AND LAKES OF INDIA:

Lakes and rivers are inseparably linked with the hydrological cycle. Very few lakes are independent of rivers; rivers usually flow into, from or through them. Lakes and reservoirs are more or less closed ecological systems involving a complex of inter-connected mechanical (currents, waves, sediment movements), physical (thermal and ice phenomena) and chemical and biological processes.   In lakes and reservoirs, with a high degree of flow, these processes are similar to those in rivers.   Big lakes with relatively weak flow with large volumes of water in relation to inflow and outflow, have eco-systems of a specific type.   These eco-systems are highly sensitive to man's activities, especially to organic pollution.

A characteristic feature of lakes is that more water is evaporated from their surface than from the surrounding land. Evaporation from lakes goes on all the time, but, on the surrounding land, there are periods when the top soil is dry and has no moisture to lose by such a process.   The main role drainage lakes play in the hydrologic cycle is in regulating stream flow, making it more even during the year. A much greater role in regulating stream flow, however, is played by storage reservoirs – the man-made lakes.

Although the recorded history of major dams in the country dates back to as early as 1700s when Jaisamund tank in Rajasthan was built, the era of present day large dams began in 1930s.   Incidentally, Vanivilas Sagar dam across river Vedavathi in Karnataka occupies the prime position being the first one to be commissioned in the country. This was also the time when dams were considered the symbols of technological advancement and development the world over. India too, not to be left behind, went ahead in constructing more and more dams. By the late 1980s, the country had more than 1500 dams. These dams, it was believed, would do it all: provide electricity to meet growing industrial and domestic demands, control devastating floods and, most importantly, provide irrigation and water to parched lands and throats. True enough; they did provide employment and irrigation facilities, moderate floods and generate electricity⁶. With the passage of time and on the implementation of several Five Year Plans, the scope of dams too expanded greatly, and, presently, these are constructed with multiple objectives viz: water storage for public supply, for irrigation reserves, for hydro-electric power, flood control, navigation as also development of fisheries including ‘sport fishing'.

India, to-date, has 975 large reservoirs of which 550 are major ones. Of the latter, 5.0% are very large (above 10,000 ha), 3.0% large (5,000 – 10,000 ha), 26.0% medium (1,000 – 5,000 ha) and the rest 66.0% are small (50 – 1,000 ha). Hirekud (74,592 ha) constructed across river Mahanadi in Orissa is the country's largest reservoir followed by Gandhi Sagar (64,750 ha) across river Chambal in Madhya Pradesh and Govind Ballabh Pant Sagar (46,539 ha) across Rend, a tributary to river Sone in Uttar Pradesh.

The main reservoirs on the Ganga river system are Govind Ballabh Pant Sagar (46,539 ha), Matatila (20,720 ha), Sarda Sagar (7,304 ha) and Nanak Sagar (4,662 ha) in Uttar Pradesh; Maithon (11,492 ha), Panchet (7,511 ha), Mayurkashi (6,734 ha), Tilaiya (6,475 ha) and Konar (2,792 ha) in Bihar; Gandhi Sagar (64,750 ha) in Madhya Pradesh and Kangsabati (11,396 ha) in West Bengal. Presently there does not exist any important reservoir on the Brahmaputra river system. Govind Sagar across river Sutlej with a waterspread area of 16,839 ha is the most important reservoir in Punjab. There is no major dam on the river Godavari; however, 188 km stretch of the river located between Dowleswaram and Ammagudem anicuts in Andhra Pradesh is ‘lacustrine' in character.   Tungabhadra (37,814 ha) in Karnataka, Nagarjuna Sagar (30,303 ha), and Nizam Sagar (14,636 ha) in Andhra Pradesh are the most important reservoirs of the Krishna river system. Krishnaraja Sagar (12,924 ha) in Karnataka and Stanley/Mettur (15,344 ha), Bhavani Sagar (7,862 ha) and Poondi (3,263 ha) in Tamil Nadu are the important reservoirs on the Cauvery river system. Rivers Narmada and Tapti have no large reservoirs at present but an epoch making ‘Narmada Project in Madhya Pradesh' is in the way. Ukai (51,282 ha) in Gujarat; Shivaji Sagar (12,100 ha) and Darwa (3,367 ha) in Maharashtra and Neyyar (9,085 ha), Malampuzha (2,313 ha) and Periyar dams (606 ha) in Kerala on different rivers of the west-coast of India are the most important reservoirs^3,7,8. Besides these, the Logtak lake (Manipur), the Collair lake (Andhra Pradesh), the Wulhar lake (Kashmir), the mountain lakes in Tal area (Uttar Pradesh) and numerous smaller waterbodies found in different locales all over the country are also potential resources. Natural lakes in the country have been estimated to offer an expanse of about 0.72 m ha. (Wealth of India, 1962). In addition, tanks and ponds found scattered all over the country account for 16,00,000 ha of waterspread area⁹.

C.             TANKS, PONDS AND IRRIGATION WELLS:

There are innumerable smaller watersheets called ‘ponds and tanks' in the country whose number and area are yet to be assessed correctly and their potential for irrigation as also fish culture determined.   The difference between ‘tanks' and ‘reservoirs' is that the impoundments generally vary not only in the extension of water area but also capacity for water holding per square meter of surface area.   Tanks record below 4.0 m depth of water in more than 75.0 – 80.0% of their area whereas the reservoirs contain 6.0 – 7.5 m depth of water in 75.0% or more of their total surface area.   Tanks, unlike the reservoirs, constructed out of concrete or masonry, are built of rubble and stone throwing a ‘bundh' across mostly seasonal streams to impound water for small-scale irrigation.   Unlike the larger impoundments, almost all the tanks contain aquatic weeds and such conditions are generally applicable to similar waterbodies in southern States like Madhya Pradesh, Maharashtra, Andhra Pradesh, Karnataka, Tamil Nadu and Kerala. The tanks in the northern Indian plains, being merely depressions in the alluvial soil where water accumulates during rains or by flood inundations, are mainly for irrigation.   Such irrigation tanks in north India and particularly in Madhya Pradesh are also known as ‘Bundhs'. Some of these smaller watersheets have bundhs on all the four sides with a small catchment and an inlet and an outlet to facilitate flow of water into the agricultural lands.   South Indian tanks, on the other hand, are built across seasonal streams and rivulets and command good catchment with a bundh only on one side provided with regulator/s to supply water to the fields. Besides the irrigation tanks, especially in South India, there are number of village ponds, farm ponds, temple ponds (Kalyanis) and fortmoats holding water all-through the year.

In the absence of proper management measures for each of the tanks in particular, the said waterbodies have been silted-up and water-holding capacity has reduced.   The infestation of noxious aquatic weeds too is hastening the silting-up of tanks and also accounting for great loss of water through evapo-transpiration. In the absence of adequate desirable management practices, majority of the perennial tanks, even in the rain-fed areas, have been converted into ‘seasonal ones' the result being low agricultural production.   Wetlands, with the provision of south-west monsoon four decades back, used to produce two crops a year, now accounts for only one crop a year.

In addition, there exists innumerable ‘irrigation wells' in the country. A quarter of the country's irrigation land makes use of water from wells of assorted dimensions.   They are most numerous in the Deccan Plateau where rainfall is low and where rocks in many areas are porous.   The Deccan wells which may be sunk to depths of 15 – 50 ft. are usually small irrigating about 1 – 3 acres of land. In the Punjab and Uttar Pradesh, wells are much larger and may have sufficient water to irrigate farms of 10 – 15 acres. In addition, with the widespread use of diesel and electricity, ‘tube-wells' are increasingly being used.   Some tube-wells are sunk to a depth of 300 ft and can be used to irrigate areas as large as thousand acres. The role played by scores of irrigation wells in the production of cash crops is on record and in view of this, proper encouragement is to be accorded in commissioning such biotopes in feasible locations in the larger interest of the community and the country.

•  POLLUTION:

Availability of potable water and in enough quantity at the right time and place is a pre-requisite for the economic and social development of any Nation¹⁰. But, most unfortunately, a serious problem that haunt the country presently is the impact of man-induced ‘pollution' in the aquatic environment. Man has made quite a few blunders in water conservation and use, the worst of them being massive pollution of rivers and lakes.   In the past, waters of rivers were considered to be ‘pure' and in ancient Indian literature, there is no mention of any further purification of river water. But, with the advent of Industrial Revolution, the picture became ‘grim' – the biotopes – the rivers in particular, are, at the moment, being used as ‘dust-bins' for the disposal of untreated domestic and industrial effluents. Pollution, arguably, is the most serious long-term biological hazard of the 20 th century since its effects are eventually felt through the food chain on ‘man'. The aquatic pollution and degradation are more serious where, in particular, urbanisation and industrialisation have advanced to a high degree. The alarming increase of human population in the country and the rapid pace of its industrialisation have created problems of disposal of waste products. As is the fact that, clean drinking water is an essential requisite for sustenance of life, it is also a sine-quo-non for the production of irrigation crops and the development of fisheries. It is also true to say that man, generally, has been slow to realise the insidious effects of pollution on plants and animals. Each cubic meter of sewage dumped into a river or lake, contaminates scores of cubic meters of clean water. Abundant water resources are of little use if they are polluted, for pollution makes them a health hazard. Rivers, as mentioned earlier, are treated as dust-bins for the various undesirable effluents from industries. The major industrial pollution sources in the country, to name a few are pulp and paper, textile, leather, rubber, chemicals, in addition to municipal and domestic waste effluents. Tentative estimates indicate that pulp and paper, textile, leather and rubber, on an average, discharge 39.28, 4.48, 2.50 and 2.40 m. gallons per day respectively. Total waste produced from these sources alone may be estimated as 5321 cusecs indicating that the demand for water exceeds the supply. Thus, the ratio of pollutants to water discharge indicated an alarming scenario¹¹.

To the polluting agents, in recent years, there have been added an array of agricultural pesticides and insecticides which are further seriously aggravating the problem of pollution both from the point of view of public health as well as aquaculture. Should the water quality of the Indian rivers and streams get degraded beyond certain limits, the situation may go out of control which may not only adversely affect all of the uses water is put to such as domestic, agriculture, aquaculture, industrial, power generation, aesthetic, navigational, recreational, etc., but the entire aquatic system may be thrown out of gear and may lead to a severe ‘biological imbalance'. The latter, if it happens, would be an ‘ecological disaster'.

•  AQUATIC WEEDS:

Aquatic weeds are defined as those unwanted and undesirable vegetation which grow and reproduce in the medium and, if left unchecked, may choke the watersheet posing serious threat to water supply conduits, turbines, channels, navigation, pisciculture, etc. The need for solving the practical field problem of weed control is more keenly felt in India than in other countries where its problem is not so acute due to temperate climate and other related conditions. Considerable quantum of water loss is there due to evapo-transpiration through certain aquatic weeds, which far exceeds the evaporation losses from open water-surface. The weed-chocked water areas will quickly deteriorate into a swamp/bog.

It is not the ‘maximum waterspread area' that desires consideration; the deserving point is the ‘depth' that matters from the point of storing the natural waters. More the expanse and extent of waterspread area, more the rate of evaporation. While power generation and navigation on rivers and reservoirs do not, as a rule, remove any of the running water they use, there is, nevertheless, loss of water through evaporation from the reservoirs that are formed behind most power dams. To over-come the evaporation problems, experiments are being conducted in spraying the water surface with ‘hexadecanol' which forms a mono-molecular film. When the entire surface is covered with the film, evaporation is reduced to 90.0%. Coconut oil is under study and hopefully, one day its application will prove to be quite economical¹².

•  SILTATION:

Over 1500 large and majority of the medium and small dams in the country today suffer from over-siltation, the result being fast deterioration of the watershed, man's intrusion on account of developmental activities, forest fires, over-grazing, unwise agricultural practices, etc. A disturbing aspect is the inadequacy of data on the volume of solids transported by the rivers. This would provide an answer to the question of the rate at which the capacities of reservoirs is decreasing as a result of their progressive filling with sand and mud and at what date they will totally cease to function. Atleast the order of magnitude of this data should be known because, in addition to a sound development of reservoir fisheries in a given time, irrigated agriculture and the generation of electricity in particular being long-term developmental projects, could be accorded priorities for achieving the envisaged goals.

In some areas, these reservoirs are not free from incursion of sewage and industrial effluents also which, of course, are man-made only.   In certain other instances, lot of stored water is being wasted through seepage, percolation and surface evaporation. This, in most of the cases, is due to faulty construction of irrigation canals. The agriculturists are also using excess water than actually needed for cultivation of varieties of crops. Conservation of water either in the soil profile or in the reservoirs deserves critical analysis and positive approach to derive maximum benefits.

In conclusion, it could only be said that: ‘if all the world's water were represented in a half-gallon milk carton, the amount of freshwater that people get-at would be what is available on the point of a needle. And all but a single droplet of that would have to be pulled out of the earth for one to use'. As a Syrian delegate warned, the day is not distant “when a drop of water cost more than a drop of oil”. Documents that were prepared for the United Nations Water Conference held during March, 1977 in Argentina¹³ are a ‘Mine' – or perhaps, a ‘Fountain' of such startling information.

Although various Agencies – Industries / Institutes, etc. are doing their best by implementing the technical know-how available in safe-guarding the interest of aquatic eco-system of the country, the ‘man in the street', yet, remains steadfastly unimpressed. This is in view of the fact that the ecological disasters caused by man are also responsible for an acute shortage of clean, safe drinking water. The realisation that water must be used as efficiently and economically as possible has prompted industry to introduce multiple and closed-cycle technologies. What is needed is a ‘grand gesture' in the interest of nature and one and all by the agencies involved as a whole. The apocryphal adage that “medicine must be unpleasant if it is to do any good” has got a ring of truth. Some 2400 years ago, Hippocrates wrote that “extreme remedies are very appropriate for extreme diseases”. The environment, inclusive of aquatic eco-system, may not have been the particular malady he had in mind, but, he had a “point”.

FRESHWATER FISH SPECIES RECORDED FROM WESTERN GHAT AREA OF KARNATAKA

•  Due priority to be given to construct small dams across all the small and big tributaries of the major river systems to facilitate effective way of flood control.

•  In order to avoid silting and for uninterrupted hydro-power generation, there is an urgent need to create small feeding reservoirs above the main impoundment, not across the river directly, but by diverting the river water a few kms. away from the main river and by connecting such smaller watersheets in the river basin to   major reservoir.

•  Farmers must be properly educated for better water-use efficiency.

•  Necessary measures to be employed to keep tanks, rivers and reservoirs safe from sewage and industrial pollution.

•  Afforestation and planting of grasses in the areas vulnerable for erosion should be adopted in the interest of wild-life and scores of industries depending upon regular supply of the raw material.

•  Commissioning of good drainage system in all the villages, towns and cities situated in low-lying river basins frequented by floods deserves attention.

•  In addition to the usual fish culture practices to be programmed in all the amenable waterbodies, introduction of the herbivorous fish species¹⁴ to keep the aquatic weeds menace under absolute check is to be considered in its right perspective.

•  Desilting of village ponds/tanks by integrating with potteries and brick industry is to be accorded top priority, which helps to increase the water holding capacity. It helps in the production of crops from the kitchen garden, agricultural crops and also to undertake fish culture in them.

•  Conservation of soil in the catchment area is regarded very important about which concerted efforts are to be made to implement the technical know-how available.

References and Books in CES