Spatial Analysis of Drought Occurrence in the Parambikulam-aliyar River Basin, Tamil Nadu

The identification and characterization of droughts are of great importance in water resources planning and management. In the present study, the standardized precipitation index (SPI) was employed to investigate the spatial characteristics of meteorological drought in the Parambikulam-Aliyar basin, Tamil Nadu. The basin was divided into 97 grid-cells of 5×5 km and monthly rainfall data for the period 1972-2011 from 28 rain gauge stations were used for spatial interpolation of rainfall using the ArcGIS. Occurrence of drought categories and cumulative drought severity were then assessed from the estimated gridded SPI values calculated from gridded rainfall at each grid and maps of spatial variation of drought characteristics were developed. The analysis of the SPI suggests that the basin had suffered severe and extreme drought in the 1970s and 1980s. The spatial extent of drought category showed that moderate and severe drought was more in the central and northern parts of the basin; while extreme drought was high in the southern parts of the basin. Drought severity map at 5 year return period indicated that the annual cumulative drought severity was high in the southern and northern parts of the basin. The results of this study can be used for identifying drought vulnerable areas, developing drought preparedness plan and mitigation strategies within the basin.