Rainfall analysis of Halia river basin and comparison of agricultural drought using remote sensing indices

Halia basin in the semi-arid region of Telangana experiences prolonged dry spells resulting in yield reduction/ crop failure in most of the years. Therefore, studying the variability in rainfall and monitoring the drought is very important for this basin. Rainfall variability significantly impacts agricultural productivity, especially in rainfed regions. This study analyzed historical rainfall patterns in the Halia Basin in Nalgonda district of Telangana state over 73 years (1951-2023) using Weather Cock software. The analysis examined rainfall trends on a weekly, monthly, seasonal, annual, and decadal basis for Halia. The annual rainfall ranged from 318 mm to 1,541 mm, with 26 to 63 rainy days per year. The highest annual rainfall of 1,541 mm and kharif season rainfall of1,233 mm occurred in 1988, distributed over 60 rainy days. The region experienced two severe meteorological droughts in 1984 and 1999 and 11 moderate drought years, with rainy days ranging from 33 to 44. Decadal rainfall analysis revealed considerable seasonal variability. Out of 73 years, agricultural droughts occurred in 34 years, lasting for 6 to 12 weeks during the kharif season. Normalized Difference Drought Index (NDDI) data, analyzed at eight-day intervals, showed strong correlations between reduced precipitation and increased drought severity. In 2014, distinct drought phases in June, August, and late September-October coincided with critical crop growth stages. Satellite imagery from June 9 and June 19, 2014, highlighted moderate to extreme drought conditions. This study demonstrated the effectiveness of integrating long-term weather data with remote sensing for comprehensive drought assessment. The findings highlight NDDI’s potential for agricultural drought monitoring and provide valuable insights for water resource management and sustainable farming practices. The consolidated 73‑year hydro‑meteorological dataset generated by this work also establishes a baseline for predictive drought‑risk modelling and climate‑smart agricultural advisories in semi‑arid river basins.