Examining drought behaviour using departure index and rainfall anomaly index in Nambiyar river basin, Tamil nadu

Abstract

Drought is one of the complex natural phenomena. In extreme cases, drought causes great damage to the economy and human life. Drought is caused by a lack of long-term rainfall. The humans as well as the environment are greatly affected due to drought. It is not related to particular climate regions but it causes a similar effect in all climatic regions of the world. There are several drought-prone areas in India so the Government of India has developed a Drought Affected Area Plan which is being implemented in drought-prone areas. An attempt has been made in this paper studying two drought indices such as Departure Index (DI) and Rainfall Anomaly Index (RAI) in the Nambiyar River Basin of Tamil Nadu to assess the drought condition. Only 3 classifications (moderate, mild, and no droughts) are observed in the Departure Index. Mild drought years are highly found in the Nambiyar River basin followed by moderate and no droughts. Chidambarapuram, Nainaputhoor station had a maximum drought of 24 years and 6 years of moderate drought is observed in Vallioor station. The frequency of drought years for RAI index are repeatedly noted high during the year 2003, 2016, and Keeriparai station had the highest negative anomaly value of -10.67 in the year 2017. Keywords: Rainfall; RAI; DI; drought; Nambiyar river basin