WATER RESOURCES: USE AND OVER-UTILIZATION OF SURFACE AND GROUND WATER
3. Lotic Ecosystems or Moving Water
Moving water or lotic ecosystems include rivers, streams, and related environments.
They are of various sizes ranging from Ganga, Yamuna, Hindon, Kali Nadi, Sutlez, Gomti, etc to the trickle of a small spring. Likewise, there is distinction on the basis of flow. On one hand there are raging torrents and waterfalls and on the other hand, the rivers whose flow is so smooth as to be almost unnoticeable. Every river varies considerably over its length, as it charges from a mountain brook to a large river.
Main Characteristics of Lotic Environment: Moving water differ from lakes and ponds as under:
(i) Current is a controlling and limiting factor.
(ii) Land water interchange is great because of the small size and depth of moving water systems as compared with lakes.
(iii) Oxygen is almost always in abundant supply except when there is pollution.
(iv) Temperature extremes tend to be greater than in standing water.
(v) The most distinctive features of moving water ecosystems are those related to their motion i.e. the rate of flow and the streams velocity. The rate of flow refers to the volume of water passing a given observation point during a specific unit of time;
It is measured in units such as m3/sec, ft3 or acre-feet/sec.
(a) Rapidly flowing water
Rapidly flowing water can be defined as the portion of the streams in which the flow is both rapid and turbulent. Consequently everything that is not attached or weighty is swept away by the current. This includes organisms and sediment particles alike. The substrate tends to be rock or gravel. The fragments are gradually rounded and smooth by the water.
(b) Slowly flowing water
A slowly flowing water ecosystem is a very different type of system from the fast streams. The flow is both slower and more likely to be laminar. The results are that the erosive power of the stream is greatly reduced, hence, smaller sediment particles (sit) and decaying organic debris, are deposited on the bottom. Besides, the slow streams have higher temperature. Consequently, planktonic organisms, espeically protozoans, occur in large number in this ecosytem. In some moving streams, the bottom muds contain more organic material than mineral fragments. In slow water streams oxygen concentration is main limiting factor. The high level of animal activity, along with an active detritus stream.
Besides, the low level of turbulence means that less oxygen is in corporate into the water at surface. Thus the dissolved oxygen content of a slowly moving stream is likely to be much lower than that of a fast-moving stream.
4. Estuaries
Water of all streams and rivers eventually drain into the sea. Estuaries is the place where this freshwater joins the salt water. As such estuaries are the transitional zones between the sea and rivers and are the sites of unique ecological properties. They are semienclosed coastal bodies of water that have a free connection with the open and within which seawater is measurably diluted with freshwater from river. However, all the rivers are not open into estuaries. Some rivers simply discharge their runoff into the ocean. Estuaries are not alike. Instead they differ in size, shape and volume of water flow, they are influenced by the geology of the region in which they occur. As the river reaches the encroaching sea, the stream carried sediments are dropped in the quiet water. These accumulate to form deltas in the upper reaches of the mouth and shorten the estuary.
The Position of Surface Water in the Country
India has been bestowed with substantial surface water resources. Overall water resources of the country have been assessed at 1880 km3 annually. Of thus, it may be possible to harness about 690 km3 of water for beneficial use. In addition, Ground Water Resources of the Country are assessed at about 452 km3.
Storages
India has constructed a large number of storages and diversions for harness its vast ware potential.
(1) Live storages built-up in the completed projects so far is about 163 km3.
(2) Another 7 km3 of live storage will be available from project under construction.
(3) 131 km3 from projects under consideration.
(4) In addition, there is a large number of small tanks whose storage adds upto about 30 km3.
Total Hydro-Power Potential of the Country has been assessed at 84,000 mW at 60 per cent load factor. Presently, Completed and on-going Schemes will exploit about 15,600 mW i.e. 20 per cent of the assesses potential. Hydropower installed capacity at the end of the Sixth Plan was 14, 450 mW. Forming about 34 per cent of the total installed capacity.
In the absence of information on actual water use by various sectors, estimates made in this regard (1985) indicated that water use may be of the order of 530 km3 is from surface Water and 180 km3 from Ground Water. Out of this, 470 km3 is for Irrigation and 70 km3 for other including Domestic (16.7 km3), Industrial (10 km3) and Thermal Plants (2.7 km3) requirements. A recent assessment puts domestic requirements in 1991 at about 26 km3.
Basin-wise Water Resources Development for 12 Major River Basins is given in the following table:
The surface water resources continue to the contaminated with run-off water from agricultural fields, containing pesticides, fertilisers, soil particles, waste chemicals from industrial and sewage from cities and rural areas.
During the dry months, water scarcity is faced even in the places like Cherrapunji and Konkan, which receive heavy rainfall. Due to the unequal distribution of rainfall our countrymen face problems of flood and famine in some parts every year.
The mass balance of annual rainfall that about 70% is lost by direct evaporation and transpiration by plants, while the remaining 30% goes into the streamflow shows it. The approximate breakup of this streamflow, as consumed by man, is 18% for irrigation, 2% for domestic use, 4% for industrial and 12% for electrical utilities. Irrigation for agricultural purposes and electric power plants are the major consumer of water.
Growth Water
Ground water resources are abundant only in the northern and coastal plains. In other parts its supply is not adequate. Ground water is roughly 210 million m3. This quantity includes recharge through infiltration, seepage and evaporisation. Even at present, our country has not been able to provide safe drinking water to all villages and towns.
Ground water contains dissolved minerals from the soil layers through which it passes.
In the process of seepage through the ground, the water gets depleted of most of the microorganism originally present in the surface water. Though the salt content may be excessively high on occasions, it is generally superior as a domestic water source. Surface water contains a lot of organic matter and mineral nutrients, which feed algae and large bacteria populations.
The total replenishable Ground Water Resources in the Country have been provisionally estimated at 45.23 million hectares meters per year. Of this, 6.93 million hectares metres is for drinking, industrial and other uses leaving 38.34 million hectares metres as utilisable Ground Water Resources for Irrigation.
Basin-wise/State-wise break-up of the potential is given in the Table 2 (next page).
Over-utilization of Water
It transpires from our water budget that, in case average annual rainfall of entire country and its total area are taken, the total water resources are of the order of 167 million hectare meters. In fact, only 66 million-hectare meters of water can be utilised by us for irrigation. As there are some financial and technological constraints we plant to use it fully only by 2010 A.D. By 1951 only 9.7 million ha metre water was used for irrigation. By 1973 it was as much as 18.4 million ha metres.
It is observed that Agriculture sector is the major user of water. The water used for irrigation which was two decades back nearly 40% has gone up to 73% by 2000 A.D. Irrigation use is very inefficient. Hence, 25-30% efficiency and method of irrigation are to be changed drastically. From the data on water use shown in the table given as under, it becomes evident that irrigation including for livestock and including power use is 79.6% and 13.7%
water respectively. Thereafter, come domestic (3.5%) and industrial (3.3%) uses.
In case the land area is taken up as a unit, the position could be different. By 1984-85 the land under irrigation almost tripled to 67.5 million ha.
Table 2.2
Water Use (India) 2000 A.D. (Available Water 1900 Million Cubic Metre Per Year)
Uses Taken Consumed Returned
Irrigation and 869 783 86
Livestock Power 150 5 145
Industry 35 10 25
Domestic 38 8 30
Total 1092 806 286
After a period of five years i.e. by 1990 another 13 million ha were to be brought under irrigation, thus, the total figure was 80 million ha. This may be adjudged against the total potential of 133 million ha by 2010 A.D. Here it may be kept in mind that it is the gross sown area and not net sown area. The former i.e. net sown area at present, more than 3%
of the net sown area is under irrigation.
It is estimated by World Health Organization (WHO) that water thirsty countries are across the oceans. Nordic water supply (Norwegian company) has been transporting fresh water i.e. clean drinking water in giant floating bags across the oceans. These floating bags are made long. Each contains 35,000 tonnes of water. The floating water bags are made of a polyester plant to build new bags of the size of supertanker, 300 metres long and a capacity of 1,00,000 tons water. In this way the Nordic company is engaged in the business
of towing fresh water from Turkey to Greek island. Its future plans include transporting water from Iran to Saudi Arabia and along Caribbean and Red Sea.
Water Supply
In our country water supply is scanty. We have more than 3000 towns, but hardly 2000 have an organized water supply. It is essential to augment coverage of water supply in urban as well as rural sectors. At present the position of water supply is as under:
(1) Low daily per capita supply, (2) Inefficient distribution,
(3) High leakage and ill managed system.
This is the position in towns. In rural sector progress in water supply has been very slow. There are about six lakh villages involved in which our 76% population lives.
Previously they were provided safe drinking water through piped water supply systems or hand pumps operated tube wells. Efforts are on and it is an expected picture that supply could be brought to about more than one lakh villages. The picture is somewhat improved during the Water Supply and Sanitation Decade (WSSD) (1981-90).
To solve the water problem, some other precautionary measures are to be taken. We have to use minimum water. The quantity of water returning after use becomes the waste water. The data for water use in our country show that waste that by 2000 A.D. out of 1900 Mm3 of water available, the country had used about more than 50% of the available water (about 1092 Mm3) for four major consumptive uses-irrigation, power generation, domestic and industrial uses.
It is held that for sustainability at least more than half of the total available water should be used annually. The country has overshot the 50% mark by 2000 A.D. which is not in our ecological interest.
Water Resources Management
Some of the central and corresponding state originations concerned with specific aspects of water resources management are as under:
(1) Central Pollution Control Board Concerning Water Quality (2) Central Water Commission Concerning Surface Water (3) Central Ground Water Board Concerning Ground Water (4) Indian Metrological Department Concerning Precipitation (5) Central Public Health and Concerning Water Supplies
Sanitation
Environment Engineering and Sewage Disposal
(Ministry of Urban Development)
(6) Ministry of Agricultural and ICAR Concerning Water use for Agricultural (7) Department of Environment Concerning Environment Forests and
Wildlife (Ministry of Impact
Assessment
Environment and Forest)
(8) Department of Concerning Watershed
Forest Management
(9) Department of Power Concerning Hydroelectric Power