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Monsoon Rain, Drought and Bihar

Dr. Pradhan Parth Sarthi

The year to year variation in Indian Summer Monsoon Rainfall (ISMR) largely affects Indian agriculture and agro-industry and finally Indian economy and Gross Domestic Product (GDP) of the country.  Any delay/early arrival of Indian Summer Monsoon (ISM) on climatologically fixed dates over selected station of always influences Indian agriculture. Any deficit/excess of ISMR during summer monsoon season i.e. 1st June to 30th September results drought and flood condition over a large area of Indian continents and has a large impact on sectors like agriculture, water resources, heath, biodiversity and others. The variation in Therefore ISM behaves like a life line of Indian people but its prediction is a challenging task for meteorologist because of its highly complex nature on the earth system.


ISM is an ideal monsoon system (defined as a seasonal reversal of surface wind system which remains in one direction for first six month and in reverse direction for next six months) but more vigorous system in compare to the other monsoon system found over the globe. During ISM, widespread ISMR is received by the whole country during 1st June to 30th September. The ISMR in a particular year may be excess or normal or deficit, if it is more or equal or below to Long Term Average (LPA) value (~88cm) of all India averaged summer monsoon rainfall. The Indian Summer Monsoon prediction in India is done by India Meteorological Department (IMD) in two folds: first in mid of May month and second in first week of July. Therefor the prediction of summer monsoon 2011 would come in middle of May month in this year.  In year 2010, monsoon rainfall shows deficit over eastern UP, Bihar, Jharkhand, Gangatic West Bengal and Assam & Meghalya by -23%, -22%, -41%, -31%, and -23% respectively while remaining regions received either excess or normal rainfall (source: IMD).


Bihar is disaster, especially floods and droughts, prone area. Almost every year, Bihar is experiencing these two natural disasters and people are losing their life and property. The area of north Bihar (north to river Ganga) is of mainly flood prone while south Bihar (south of river Ganga) is under the influence of drought prone. In recent years, the frequency of occurrence of these disasters is increased. Based on the observed IMD rainfall data for the period of 2005-2009 for the 25 districts of Bihar, it is found that Kishanganj (-31%) and Katihar (-29%) districts of north Bihar experience a remarkable deficit of summer monsoon rainfall in last year. The south part of Bihar especially Bhojpur (-28%), Buxar (-12%), Gaya (-17%), Rohtas (-12%), Kamur (% negative departure is not show) show a remarkable deficit of rainfall in last five years.


In district of Bhojpur, farmers are mainly depends on ISMR and from the supply of water through canals from Sone river. In the last five years, ISMR shows erratic behaviour, may be due to global warming, and water from sone river is always matter of dispute between Bihar and Utter Pradesh. Due to both reasons, farmers are not getting ample of water for agriculture purposes and with acute shortage of water for irrigation purposes for Rabi and Kharif crops, farmers are always in great trouble in Bhojpur and it seems that agriculture is now not a profitable business for them.

The districts of Rohtas and Kamur are known as “Bowl of Rice” due to large cultivation of high quality of rice during monsoon season. In Kamur, Paddy is cultivated in the area of 111000 Hectare and the area covered by canal is only 55743 Hectare (source: Govt of Bihar).  In this district, water is supplied through canal of Karmanasha, Durgawati and Kudra rivers for irrigation purposes in this district. This district is largely experiencing uneven distribution and deficit of ISMR at up to the level of blocks in last five years. Therefore, level of ground water in some of the blocks is continuously going down since it is recharged by only rainfall during monsoon season and existing canal is not able to provide sufficient water for irrigation. In the months of May in last few years, the situation starts becoming worst especially in Chainpur block of Kamur. Therefore farmers, especially small, are not getting any benefit from the agriculture and are under great economic stress. To stop the migration of these framers towards mega cities or town for money, ample irrigation facility and agro industry must be created in this region.


(The writer is Faculty and Academic Coordinator,Centre for Environmental SciencesCentral University of Bihar)


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