Water Management Strategies for Bihar
R. C. Srivastava
Dr. Rajendra Prasad Central Agricultural University, Pusa (Bihar)
The State of Bihar is bestowed with ample water resource but still for most of crops, the productivity is lowest in country. A major reason for this is lack of irrigation with percentage of irrigated area hovering around 50 to 60%. About 27% of area is irrigated by canal system which has its inherent water availability problems. Rest area is irrigated with groundwater with extraction by diesel operated pumps. The high cost of diesel operated pump create two fold problem: One is cost which is about 5 times that of electric pumps and second is use of centrifugal pumps. The centrifugal pumps are inefficient and when the water level goes down beyond 6 m the farmer has to lower the pump in a pit combination of all these factors force farmer to restrict number of irrigation to base minimum and due to this, the productivity of even irrigated area is less.
The water management plan/strategy for the state can be two pronged (i) Providing irrigation to > 80% irrigated area with ultimate objective being 100% and (ii) enhancing water use efficiency in both already irrigated and newly irrigated areas. Following outlines the steps to be taken to fulfil these objectives:
A. Providing irrigation to > 80% irrigated area
The strategy for this objective will be area specific. For this, we can divide state in three geographical areas, i.e. Gangetic plains, rich in ground water; plateau and hilly regions of Nawada, Aurangabad, Kaimur, Jamui, Banka and Shekhapura; and Dhab, Diara and Tal areas of riverine areas.
(i) Gangetic Plains: There should be time bound plan to phase out diesel pumps. They should be replaced by 3 hp single phase submersible pumps in tube wells which are near to homestead where single phase connection is available. For far off tubewells, a decision have to be taken whether they should be fed by 3 phase dedicated feeder or by solar tree, depending upon the cost.
(ii) Plateau and hilly regions :
The plateau and hilly regions can be irrigated by adopting any of the following technology.
(a) Tank cum well system: In this system, a series of tanks followed by open dug is constructed in a drainage line. The cultivated area on both sides of drainage line can be irrigated first by using tank water and then using well water. This system was conceptualized and evaluated by author during 1999-2004 for plateau areas of Odisha and was found very effective in providing round the year reliable irrigation to a two crop rotation.
(b) Dr. RPCAU, Pusa has developed a boat based solar powered pumping system which can pump water from river to cultivated area located on river bank. This system can be used to irrigate narrow valley lands in hilly and plateau region. These narrow valley lands area quite fertile and if provided irrigation can be very productive.
(c) The plateau and hilly regions are criss crossed with rivulets. A good number of them have flow upto March. A combination of collapsible gate and solar tree based pumping system can facilitate storage of water in river channel itself and pumping to cultivated areas on the bank of river.
(iii) Tal, Dhab and Diara areas:
Out of 93 lakh ha geographical area about 16% i.e. 15 lakh ha area is categorised as Tal, Dhab and Diara areas. These areas remain submerged during monsoon months but are suitable for cultivation during post monsoon months. Although they have water available nearby but costly extraction of it make irrigation a costly affair. Due to this crops are grown on residual moisture with poor productivity. Dr. RPCAU, Pusa has developed/ in process of developing technologies for pumping water in these areas.
(a) Floating solar powered pumping systems :
This system contains a country boat with solar panels of 1800 watts which power a 2 hp submersible pump. The system can pump water from river and can irrigate areas on side of river. It can move both along the river and therefore reduce the length of conveyance pipe requirement. The cost per hour is just Rs.32/- per hour which will go down further to Rs.17/- per hour.
(b) The tal areas of Bihar are quite productive with sufficient amount of water availability no electrification of this vast area is possible due to it getting flooded during monsoon. Thus diesel operated pumps remain only option which makes irrigation unaffordable. With this in mind, Dr. RPCAU, Pusa is developing two mobile Solar powered pumping systems one for pumping water from nearby water bodies and another from tube wells.
2. Enhancing water use efficiency:
To enhance water use efficiency, two major crops Maize (rabi) and sugarcane should be brought under drip irrigation. However, this should not be traditional drip system but should have two components: one drip system in paired rows of maize/sugarcane and one micro sprinkler for pulse/vegetable as inter crop. This will not only save irrigation but also increase income of farmer as well as replenish depletion of nutrients by main crop.
Thus, with above mention steps, the whole area can be brought under reliable irrigation round the year and state can get rid of drought.