Aquatic ecosystems (rivers, lakes, ocean, etc.) contribute to a large proportion of the planet's biotic productivity as about 30 % of the world's primary productivity comes from plants living in the ocean. These ecosystems also include wetlands located at lake shores, river banks, the ocean shoreline, and any habitat where the soil or vegetation is submerged for some duration. When compared to terrestrial communities, aquatic communities are limited abiotically in several different ways (Ramachandra, et al. 2005). 

• Organisms in aquatic systems survive partial to total submergence. Water submergence has an effect on the availability of atmospheric oxygen, which is required for respiration, and solar radiation, which is needed in photosynthesis.
• Some organisms in aquatic systems have to deal with dissolved salts in their immediate environment. This condition has caused these forms of life to develop physiological adaptations to deal with this problem.
• Aquatic ecosystems are nutritionally limited by phosphorus and iron, rather than nitrogen and
• These are generally cooler than terrestrial systems which limit metabolic activity.

Aquatic ecosystems have been subjected to various levels of stresses in India, due to unplanned developmental activities in the last century leading to serious environmental degradation. Anthropogenic activities involving changes in land use ultimately affects the receiving water in that drainage. Activities include agriculture –inorganic fertliser, pesticides and herbicides applied to crops, silt washed away because of vegetation removal, or even atmospheric deposition, or disposal of solid and liquid wastes.  Thus, aquatic ecosystems are exposed to all local disturbances regardless of where they occur. In addition, waterways have been used for numerous activities other than providing habitat to aquatic organisms. They have been altered for transportation, diverted for agricultural and municipal needs, dammed for energy, used as an industrial coolant, and straightened for convenience. These uses, misuses and exploitation have taken their toll as evidenced by declines in fisheries, floods, droughts, loss of biodiversity and communities trying to deal with finite water supplies. The traits that make aquatic ecosystems particularly vulnerable also make them useful for monitoring environmental quality. Water serves to integrate these impacts by distributing them among the elements within these ecosystems. Although dilution is occurring, subtle changes can be detected in habitats or organisms over a much larger area that may be the result of a single point source. A clean ecosystem with a healthy biological community will be indicative of the condition of the terrestrial habitat in the watershed. Despite few attempts, much needs to be done to effectively manage and conserve aquatic resources. As is evident from the scientific literatures little is known of the national trends in populations, diversity, or biomass of diatoms, algae, and protozoa even though they provide basic functions of photosynthesis, production, and decomposition critical to the normal functioning of aquatic ecosystems. This necessitates detailed scientific investigations and without increased monitoring, some very basic attributes of aquatic systems may be unknowingly lost or severely degraded. Subtle changes such as losses of island habitat and constant water depth or level may lead to drastic declines in productivity or diversity. The loss of some of these vital components of ecosystems may be impossible to restore (Ramachandra, 2006).

Water has a unique place of all the planet’s renewable resources. It is essential for sustaining all forms of life, food production, economic development, and for general well being. It is impossible to substitute for most of its uses, difficult to de-pollute, expensive to transport, and it is truly a unique gift to mankind from nature. Water is also one of the most manageable of the natural resources as it is capable of diversion, transport, storage, and recycling. All these properties impart to water its great utility for human beings. The surface water and groundwater resources of the country play a major role in agriculture, hydropower generation, livestock production, industrial activities, forestry, fisheries, navigation, recreational activities, etc. According to National Water Policy in the planning and operation of systems, water allocation priorities are: (i) drinking water, (ii) irrigation, (iii) hydropower, (iv) ecology, (v) agro-industries and non-agricultural industries, and (vi) navigation.

India receives annual precipitation of about 4000 km³, including snowfall. Out of this, monsoon rainfall is of the order of 3000 km3. Rainfall in India is dependent on the south-west and north-east monsoons, on shallow cyclonic depressions and disturbances and on local storms. Most of it takes place under the influence of south-west monsoon between June and September except in Tamil Nadu, where it is under the influence of north-east monsoon during October and November. India is gifted with a river system comprising more than 20 major rivers with several tributaries. Many of these rivers are perennial and some of these are seasonal. The rivers like Ganges, Brahmaputra and Indus originate from the Himalayas and carry water throughout the year. The snow and ice melt of the Himalayas and the base flow contribute the flows during the lean season. Lal (2001) mentioned that more than 50% of water resources of India are located in various tributaries of these river systems. Average water yield per unit area of the Himalayan Rivers is almost double that of the south peninsular rivers system, indicating the importance of snow and glacier melt contribution from the high mountains. Apart from the water available in the various rivers of the country, the groundwater is also an important source of water for drinking, irrigation, industrial uses, etc. It accounts for about 80% of domestic water requirement and more than 45% of the total irrigation in the country. As per the international norms, if per-capita water availability is less than 1700 m3 per year then the country is categorized as water stressed and if it is less than 1000 m3 per capita per year then the country is classified as water scarce. In India per capita surface water availability in the years 1991 and 2001 were 2309 and 1902 m³ and these are projected to reduce to 1401 and 1191 m3 by the years 2025 and 2050 respectively. Hence, there is a need for proper planning, development and management of the greatest assets of the country, viz. water and land resources for raising the standards of living of the millions of people, particularly in the rural areas.

1. WATER RESOURCES: Although India occupies only 3.29 million km2 geographical areas, which forms 2.4% of the world’s land area, it supports over 15% of the world’s population. The population of India as on 1 March 2001 stood at 1,027,015,247 persons. Thus, India supports about 1/6th of world population, 1/50th of world’s land and 1/25th of world’s water resources. India also has a livestock population of 500 million, which is about 20% of the world’s total livestock population. More than half of these are cattle, forming the backbone of Indian agriculture.

Water resources potential of the country has been assessed from time to time by different agencies. The assessment of 1869 km³ (or Billion Cubic Metre i.e. BCM) of CentralWater Commission (CWC) carried out in1993 is generally considered as reliable.  Within the limitations of physiographic conditions, socio political environment, legal and constitutional constraints and the technology available at hand, the utilizable water resources of the country have been assessed at 1123 km³, of which 690 km3 is from surface water and 433 km³ from ground water sources. The irrigation potential of the country has been estimated at around 139.9 mha without inter-basin sharing of water, and 175 mha with interbasin sharing. The Central Ground Water Board (CGWB) has estimated that it is possible to increase the ground water availability by about 36 km³, by taking up rainwater harvesting and artificial recharge over an area of 45 mha through non-committed surplus monsoon runoff. Thus the groundwater availability may correspondingly increase.

The annual potential natural groundwater recharge from rainfall in India is about 342.43 km³, which is 8.56% of total annual rainfall of the country. The annual potential groundwater recharge augmentation from canal irrigation system is about 89.46 km3. Thus, total replenishable groundwater resource of the country is assessed as 431.89%. After allotting 15% of this quantity for drinking, and 6 km3 for industrial purposes, the remaining can be utilized for irrigation purposes. Thus, the available groundwater resource for irrigation is 361 km³, of which utilizable quantity (90%) is 325 km³. It is estimated that approximately 25% of the annual distribution of rainfall is being utilised at present. Further, the water resources in the country present two contrasting scenario, viz (i) one of harmful plenty in the form of devastating floods in few regions; and (ii) acute scarcity of water resulting in severe drought conditions in some other regions, that has become a recurring feature. The Ministry of Rural Development is particularly concerned with the ground water situation, accounting for 85 percent of the rural water supply in the country. In recent years, the sustainability of the source has emerged as a major issue. Among the various factors responsible, the competing demands from the irrigation sector, using 85 percent of ground water, is a major factor adversely affecting the sustainability of the drinking water source. The situation gets further aggravated in the absence of a well conceived institutional mechanism for regulated development of ground water. In this connection, it may be relevant to mention that all the States have been continuously advised to adopt the Model Bill to regulate and control development of ground water circulated by Ministry of Water Resources. Over exploitation of ground water not only affects sustainability of the resource but also affects the quality, as manifested through arsenic problem in parts of West Bengal, coastal salinity in parts of Tamil Nadu and Gujarat and fluoride problem in a number of States (Kolar in Karnataka, Palghat, Wayanad, etc. in Kerala). The government’s concern since independence has been raising the quality of life and the health of the people. Several initiatives were taken at policy formulation level leading to various programmes in this direction.

1.2 NATIONAL WATER POLICY: As per Seventh Schedule of the Indian Constitution (as per List-II – State list,), water is a State subject and water resources projects are owned and operated by the State Governments (http://wrmin.nic.in/policy). However, this is subject to the provisions of entry of List-I – Union List, wherein Union Government has been given powers to regulate and develop inter-State rivers and river valleys to the extent such regulation and development under the control of Union is declared by Parliament by Law to be expedient in public interest. Further Economic and Social Planning has been included in List-III – Concurrent List, Item 20. Some salient features of the NWP 2002 are:

• The NWP (http://wrmin.nic.in/policy/nwp2002.pdf) defines water as a prime natural resource, a basic human need and a precious national asset, to be planned, developed, conserved and managed in an integrated and environmentally sound basis, keeping in view the socio-economic aspects and the needs of the States. It recognizes water as a crucial element in developmental planning, to be managed in a sustainable manner and guided by the national perspective. Water as a resource is one and indivisible: rainfall, river waters, surface ponds and lakes and ground water are all part of one system.
• It acknowledges integrated and coordinated development of surface and ground waters and their conjunctive use, the socio-economic, environmental and sustainability issues in water resources development; need for appropriate resettlement and rehabilitation of project affected people; problems of time and cost over runs in project construction; problems of salinity and water logging in some irrigation commands; and issues of equity and social justice in water distribution; and stipulates that all these concerns need to be addressed on basis of common policies and strategies.
• It acknowledges the importance of all types of practices, the traditional practices like rainwater harvesting, preservation of forests; the modern conventional practices like water shed management, soil conservation; and the modern non-conventional methods like inter-basin sharing of water, artificial recharge of ground water and desalination of sea water.
• It emphasizes multi-sect-oral, multi-disciplinary planning with participatory approach, for the entire river basin.
• The water allocation priorities are drinking water, irrigation, hydro-power, ecology, industrial use and navigation, in that order. It specifically stipulates that drinking water requirement shall be first charge on any available water.
• It encourages participation of private sector in planning, development and management of water resources projects with a view to introduce innovative ideas, generate financial resources, and bring in better management practices. All models of private sector participation, viz. build, own, operate and transfer, are acceptable.
• It recommends water sharing and distribution amongst States guided by a National perspective with due regards to the availability and needs within a basin.
• It stipulates that there is an urgent need for paradigm shift from creation of new projects to improvement of the performance of existing projects.

• The erosion of land, whether by the sea in coastal areas or by river waters inland, should be minimized by suitable cost-effective measures. The States and Union Territories should also undertake all requisite steps to ensure that indiscriminate occupation and exploitation of coastal strips of land are discouraged and that the location of economic activities in areas adjacent to the sea is regulated.
• Each coastal State should prepare a comprehensive coastal land management plan, keeping in view the environmental and ecological impacts, and regulate the developmental activities accordingly.

1.3 INFLUENCE OF ANTHROPOGENIC ACTIVITIES ON HYDROLOGICAL CYCLE: The hydrological cycle is being modified quantitatively and qualitatively in many river basins of our country due to unplanned developmental activities, which is evident from large scale land cover changes altering the hydrological regime. Human activities affecting the hydrological regime can be classified into four major groups:

1. activities which affect river runoff by diverting water from rivers, lakes, and reservoirs or by groundwater extraction,
2. activities modifying the river channels, e.g. construction of reservoirs and ponds, levees and river training, channel dredging, etc.
3. activities due to which runoff and other water balance components are modified due to impacts of basin surface e.g. agricultural practices, drainage of swamps, afforestation or deforestation, urbanization, etc. and
4. activities which may induce climate changes at regional or global scale, e.g. modifying the composition of atmosphere by increasing the ‘greenhouse’ gases or by increased evaporation caused by large scale water projects.

For understanding the effects appropriately, maintaining water quality, regular monitoring of aquatic systems and effective legal framework has to be adopted.

1.4 NEED FOR MAINTAINING QUALITY, LEGAL FRAMEWORK: In view of the existing status of water resources and increasing demands of water for meeting the requirements of the rapidly growing population of the state as well as the problems that are likely to arise in future, a holistic, well planned long-term strategy is needed for sustainable water resources management in India. The water resources management practices may be based on increasing the water supply and managing the water demand under the stressed water availability conditions. Data monitoring, processing, storage, retrieval and dissemination constitute the very important aspects of the water resources management. These data may be utilized not only for management but also for the planning and design of the water resources structures. In addition to these, now a days decision support systems are being developed for providing the necessary inputs to the decision makers for water resources management. Also, knowledge sharing, people’s participation, mass communication and capacity building are essential for effective water resources management.

Water-quality monitoring methods can contribute to sustainable development actively and significantly, if they:

•  make it possible to identify the economic activities or social behavior causing the pollution (point source or diffuse);
• are chosen for their ability to provide results useful not only as stand-alone data, but also to be aggregated into indexes that are understandable by the various stakeholders with an interest in water quality;
• facilitate the transmission of information, so the results must be quickly and easily accessible;
• are affordable in the economic sense on a long-term basis, while creating quality jobs within the community. The financial resources saved on quality monitoring can afterwards be injected into preservation or rehabilitation activities;
• need as little energy and materials as possible from a life-cycle perspective;
• avoid the use of hazardous substances;
• are socially accepted, in terms of utility and usability, and produce information suitable for end users, such as decision makers.

In addition:

• the data gathered on water bodies and ecosystems must be broad (spatial and temporal coverage, water-quality criteria) and accurate enough to ensure good water quality globally;
• when choosing a given method, one should consider that the data obtained are more likely to be integrated into broader environmental or sustainability-monitoring frameworks, so water-quality indicators should be considered alongside soil, air and effluent indicators, and, possibly even better, social and economic indicators;
• standard methods and equipment should allow for the comparison of the (quantitative) data gathered by the organizations and agencies involved; and,
• the cost and the level of accuracy of the methods employed must be consistent with the kind of information needed and the objectives in place.