Drought assessment in the Dhar and Mewat Districts of India using meteorological, hydrological and remote-sensing derived indices

Several drought indices have been developed during the past decades for monitoring the onset, duration and intensity of drought in different agro-climatic regions. The present study attempts to monitor drought in two underprivileged districts, i.e., Mewat of Haryana and Dhar of Madhya Pradesh state of India, using the remote-sensing-derived Vegetation Condition Index (VCI), meteorological-based Standardized Precipitation Index (SPI) and hydrological-based Standardized Water Level Index (SWI). The time series SPOT VGT NDVI data of the rain-fed crop season (kharif) were used for a 13-year period (1998-2010) to assess the long-term vegetation conditions and compare with the meteorological and hydrological based drought indices. It was observed that the NDVI profile of the crop-growing season was remarkably shifted and shortened during drought years, indicating a delay in crop sowing. A detailed spatiotemporal analysis of drought dynamics was carried out using the VCI, which revealed the occurrence of a severe drought in Mewat and Dhar during the year 2002 and 2008, respectively. The correlation coefficient obtained between the VCI and SPI in Dhar (r = 0.55) and Mewat (r = 0.74) shows good agreement between satellite-derived and meteorological drought indices. However, it is also noteworthy that the correlation coefficient between the VCI and SPI is mainly region specific and varies with timescale. In spite of good agreement between these two indices during severe drought years, the drought estimates were found non-analogous during the years with moderate drought. The study also shows that hydrological drought may not correspond with agricultural drought in every year. There is an increasing tendency in both the pre- and post-monsoon SWI indicating a gradual increase in aquifer stress in the region. Although the years with distinct agricultural drought agree with the meteorological drought years, they do not correspond with hydrological drought in most of the years. However, the VCI based on real-time satellite data can be used for drought early warning, and thus it can be helpful for policy makers to reduce the adverse impact of drought.