Assam is very rich in water resources. Water is important and essential for human beings, animals and plants and at the same time it is essential for agricultural development, industry, animal husbandry and overall economic development is depended upon it. Water available in the State can be classified as surface water and ground water. Both surface and groundwater is obtained from rainfall. Assam experiences the predominant influence of the south-west tropical monsoon which reigns from April to October with occasional winter showers. The average annual rainfall in the State varies from 1780 to 3050 mm. Water resources of the State as a whole are substantial. About 8251 sq km, which is 10.5% of the total geographical area of the State, is occupied by surface water bodies. Among this about 6503 sq km is covered by the river systems including the mighty Brahmaputra and 1, 34, 137 ha by natural wetlands including seasonal and permanent waterlogged and marshy areas and man-made. Annual Groundwater Draft is estimated as 5.44 billion cubic metre of which 4.85 billion cubic metre is for irrigation and 0.59 billion cubic metre is for domestic and industrial uses. Water is available from both from over ground (surface run water) and underground sources. The success in raising a good agricultural crops as well as running of allied activities depend upon the availability of adequate quantity of surface water or from ground storage of water. It would be better to study these sources of water resources in detail. Assam is rich in surface water. Rainfall and rivers are the two major sources of surface water. The major portion of surface water in Assam is derived from rainfall.
Assam is famous for heavy rainfall. .Rainfall in Assam is usually heavy due to its peculiar geographical position. In Assam, the rainfall is not fairly widespread throughout the year. About 90% of the total rainfall occurs during the monsoon periods. Another important source of surface water in Assam is ‘the major river of the State. In Assam there are huge number of rivers, ponds and wetland which are providing water in the various parts of the state throughout the year. Brahmaputra is the major river of Assam which goes through all the plain districts excepting Cachar. Another major river Barak is flowing through the undivided Cachar district of Assam. The ground water potential in Assam is also quite high. Out of the total area worthy of ground water exploration, nearly two-third of this potential has already been covered. There are about 16 billion cubic metres of ground water available for exploitation but the water potential is not utilize for providing irrigation facilities. Moreover, there is also scarcity of potable drinking water in various parts of the State.
State Water Policy
The State Water policy of Assam was drafted in 2007 but has not been implemented yet. It aims to ensure preservation of all water resources and to optimise the utilisation of the available resources.
Water Resources Department:
The concerned department used to perform under the name Public Works Department earlier. In 1970, it bifurcated from PWD. In 1974, irrigation department was split from it and both became independent departments. Subsequently, it was named as Water Resources Department in the year 2002.
Flood Control:
The total area of flood prone regions in Assam comprises about 39.58% of the total land area of Assam, which is four times the national mark of the flood prone areas in India. During post independence period, Assam faced major floods in 1954, 1962, 1972, 1977, 1984, 1988, 1998, 2002 and 2004. Three to four waves of flood ravage the flood prone areas of Assam almost every year Average annual loss due to flood in Assam reached up to hundreds of crores and it worsened in subsequent years (up to 771 crores in 2004).
The National Flood Policy of 1954 boosted different flood control activities in Assam with the identification of various measures taken to provide immediate relief to the flood and erosion ravaged state. It also initiated construction of embankment and flood walls, river training and bank protection measures, river channelisation with protection device, drain-age improvement, flood forecasting and warning as well as flood zoning.
The Water Resources Department has been implement-ing these flood and riverbank erosion management measures as per recommendation of Rastriya Barh Ayog (RBA). Implementation of the above measures have been able to protect about 53.42% of areas out of the total flood prone areas (31.05 Lakh Hectare) as identified by the RBA in the State.