Hydrological Dry Spells and its Impact on Dry Land Agriculture in Anantapur District (AP) / K.V. Suryanarayana, Murthy Rao V. Khokalay and S. Krishnaiah

Due to uneven distribution of rainfall and prolonged dry spells during Monsoon season and in crop period, the dry land agriculture in arid and semi arid region is becoming difficult. The identification of dry spells and wet spells to find out drought occurring conditions is complex because of the fact that it requires analyzation of vast hydrological data in a systematic manner. The laborious process can be made easy with the advent of using computers and the appropriate data management software. Anantapur being a drought affected district in Andhrapradesh due to prolonged dry spells and ill distributed rainfall the district under went a metamorphosis from drought to desert prone area. Hence the present study is carried out to identify the droughts by analyzing the daily rainfall and evaporation data for a period of 21 years from 1987 to 2008 by using personal computer. From the data analysis, the dry days, wet days, dry spells, wet spells. monthly, seasonal and annual rainfall driest and wettest months are obtained. Groundnut is the predominant rainfed crop in Anantapur. The crop yields are compared with the annual rainfall. The results yields that, whenever the annual rainfall is less than the normal annual rainfall, wet days are less than 22, dry spells more than 5 and the dry spells with more than 30 days duration occur during June, July & August, then the particular year may be identified as drought in Anantapur district. This consequently shows decline of ground nut crop yield. Whenever the onset of Monsoons was late and consequently it led to the late sowing of ground nut crop which results in either crop reduction or failure. The reservoir operation, agricultural planning, release of water to canals for irrigation arranging life saving irrigations to rain fed crops and cloud seeding operations can be planned based on the identification of dry spells.