Annual and seasonal rainfall variability analysis at micro-level administrative units within Vijayapura district under hot semi arid eco-sub region of the Deccan Plateau of India

Abstract

This study analyzes annual and seasonal rainfall variability in Vijayapura district, Karnataka, using 2013-2023 data from the Karnataka State Natural Disaster Monitoring Centre (KSNDMC). Results show that the district received adecadal mean annual rainfall of 511.43 mm, with high inter-annual variability (Coefficient of Variation (CV) 31.24%) andfrequent dry spells. The south-west monsoon contributes nearly 70 per cent of the annual rainfall, while the north-eastmonsoon (16.7%) and pre-monsoon (14%) were highly erratic and winter rains were negligible. Hobli (Cluster of villages)level assessment highlights sharp spatial contrasts viz., Nidagundi faces extreme aridity (< 400 mm, CV > 50%), while areaslike Indi, Vijayapura and Ballolli exhibited relatively stable rainfall and rainy days. Across the district, 65-75% of rainy daysoccur during the south-west monsoon, underscoring its dominance in sustaining agriculture. However, the uneven distributionand high variability in other seasons intensify the risks of drought, crop failure and groundwater dependence. In general,findings emphasize that rainfall variability, rather than mean rainfall, is the key determinant of agricultural reliability. Thestudy advocates adaptive strategies such as rainwater harvesting, in-situ moisture conservation, watershed development,supplemental irrigation, crop diversification and contingency crop planning to strengthen resilience and ensure sustainableagriculture in the semi-arid tropics.