Irrigation and Water Resources Development provides the basic infrastructure for the growth of economy of the country and large investment has been made for the purpose in our country. Irrigation is an artificial application of water to the soil for crop production by constructing headworks (weir) across a river in case of flow irrigation system. In lift, irrigation system water required for irrigation purpose has been lifted from the river as the situation commands by diesel operated or electricity power operated barge mounted pump. In third case where these two systems are not feasible required water are extracted from the water bearing aquifer beneath the ground level by means of deep tube well assembly. Besides these popular system of irrigation there are sprinkler system and drip irrigation system. In a world of explosive population growth, particularly in developing nations, it is the need of the time to enhance the growth of food grain production keeping in conformity with the increase in population. The increase in agricultural production in general and food grain production in particular has not kept pace with the growth of the population by ushering the traditional cultivation system.
Necessity of irrigation in the state of Assam:
The economy of Assam is predominantly agricultural based, as about 85% of the populations live on agricultural activities for their livelihood and 15 % is dependent on allied services. The total geographical area of the State is 78.483-lakh hectare. Gross cropped area of the State is 41, 59,977 hectare out of which net area shown is 28, 10,597 hectare that is 35.81% of the geographical area of Assam. In order to cope up with the food deficit caused by growth in population and to ensure food security, multiple cropping with irrigation support is highly necessary. Moreover, due to vagaries of nature, global warming, ecological imbalance and erratic monsoon, the rain fall is not taking place at right time to the help of the agricultural practices. As such, irrigation input is found to be the only alternative, which can provide right amount of water at right time to carry out agricultural activity.
Creation of irrigation Department:
In due cognizance of the criticality of irrigated agriculture in ensuring adequate production which results both in food security and economic growth , Irrigation Department was initiated its independent functioning in the year 1974 by bifurcating it from the erstwhile Flood Control and Irrigation Department. The Department is playing a vital role in the development of irrigation potential of Assam by harnessing the rich surface water and ground water resources of the state. The Irrigation Department has achieved an irrigation potential of 8.82 lakh hectares up to March 2015 that includes the potential created by ASMIDC (1, 49,205 Ha) merged with Irrigation Department. However, in reality the potential created by ASMIDC have no existence in the field as they are of short-lived nature (LLP & STW). Accordingly in practice, potential created by Irrigation Department is 7, 32,599 Ha neglecting the figure created by ASMIDC.
Irrigation development in Assam:
Out of total geographical area of 78.438 lakh hectares, total crop area of the State is about 41.59 lakh hectares as per latest available figures. The ultimate irrigation potential is assessed as 27 lakh hectares.
Irrigation Department has assessed to cover an ultimate Irrigation potential to the tune of 27 lakh hectare in phased manner by harnessing the rich surface water and ground water resources of the State. Irrigation Department of Assam executes and maintains Major schemes (potential above 10,000 hectare), Medium schemes (potential between 2,000 hectare to 10,000 hectare) and Minor schemes (potential below 2,000 hectare). It is planned to provide Irrigation facilities to 17 lakh hectare of cropped area through Minor Irrigation schemes and remaining 10 lakh hectares through Major and Medium Irrigation projects out of the ultimate Irrigation potential. The area to be covered by Minor Irrigation schemes (17 lakh hectares) is further categorized as 10 lakh hectare from ground water resources and remaining 7 lakh hectares from surface water resources.
The popular means of irrigation adopted in the State are:
(1) Flow Irrigation System where the water level are raised in the flowing river by constructing headworks (weir) across a river and water required for Irrigation are diverted to the crop field through regulator and canal systems.
(2) In lift irrigation system water required for irrigation purpose has been lifted from the river as the situation commands by diesel operated or electrical power operated barge mounted pump sets and water for irrigation purpose are delivered through canal system. Lift Irrigation system is preferable where the source river is of the nature of deep gorge type.
(3) In third case where these two systems are not feasible, required water are extracted from the water bearing aquifer beneath the ground level by means of deep tube well assembly. Besides these popular system of irrigation there are sprinkler system and drip irrigation system.
The Irrigation Department is the nodal authority of the Government of Assam responsible for harnessing water resources by constructing Weirs/Headworks and networks of water carrier system/canal.