Change in climate water balance and agro-climatic situational analysis for crop planning in southern Odisha

摘要

Tribal dominant undivided Koraput district of southern Odisha represents four Agro-climatic zones viz. Eastern Ghat High Land, North Eastern Ghat, South Eastern Ghat and Western Undulating zones. Based on altitude, soil type, rainfall, irrigation, topography and cropping pattern, each agro-climatic zone is sub-divided into different agro-ecological situations (AESs). As water balance is an important tool to develop plan for optimal utilization of scarce water, the parameters of climatic water balancefor three agro-climatic zones of southern Odisha were computed by employing Thornthwaite (1948) method using weather parameters like rainfall, temperature etc, for three decades 1971-1980, 1981-90 and 1991-2000 and 1971-2000 (i.e. for the normal year).Potential evapotranspiration was determined by Hargreaves method. From the decadal change of water balance it was found that in different block years the precipitation (P) almost remaining the same, the potential (PE) and actual evapotranspiration (AE) have increased from 1702.6 to 1774 mm and 937.7 to 960.6 mm, respectively. The water surplus (WS) has decreased from 493 to 449 mm and water deficit (WD) has increased from 765 to 814 mm. The normal water balance (1971-2000) shows that the average annualPE, P, AE, WD and WS is 1689.9 mm, 1397.7 mm, 946.1 mm, 743.8 mm and 470.4 mm, respectively. During October to May, there has been a constant spell of deficit. However, soil has been almost completely recharged during the month of June. Based on the criteria of Moisture Index (MI) on annual basis, the region is slightly moist. In rabi season it is extremely dry and in kharif it is wet. The length of crop growing season has been assessed and found as normal varying from 163 to 180 days with slight moisture stress and 178 to 210 days with moderate stress condition. Further, the season starts from mid May to November 1 to 23 and accordingly a remunerative alternate crop planning has been suggested.