A Comparison of the Frequency and Intensity of Standardized Precipitation Index (SPI) and the Rainfall Anomaly Index (RAI) during the Meteorological Drought across Harohar-Punpun Basin (India)

The term "drought" applies to a prolonged period when there is a water shortage because of insufficient precipitation, an excessive rate of evaporation, and excessive use of water from reservoirs and other storage, including ground water. It is a slow-onset phenomenon that can have significant social, economic, and environmental impacts. Both the frequency and severity of droughts are increasing globally due to manmade and natural factors. This study looked at how well SPIs (3, 6, 12-month time scales) and RAI (Rainfall Anomaly Index) performed at identifying drought occurrences over a period of 70 years (1951 to 2021) in India's Agro-Ecological Zones. The RAI and SPI values were computed using rainfall data from 9 meteorological stations located throughout the Harohar- Punpun Basin. According to the results, the RAI is more capable than SPIs in detecting historical records of actual occurrences. Additionally, RAI is more effective than SPIs for determining both short- and long-term droughts. Since RAI can better capture the true nature of the drought situation in the Harohar-Punpun Basin, it appears to be more responsive to drought circumstances. The primary causes of drought, according to the study, include minor variations in precipitation, willful ground water removal, changing cropping patterns, and substantial changes in land use. Regional planners and administrators will surely find use for this scientific study and integrated watershed management methods for sustainable water resource management, particularly for this region.