Assessing long-term rainfall trends using non-parametric approach in Warangal district, Telangana, India

Assessing long-term rainfall variability is crucial for understanding regional hydroclimatic dynamics and informing water resource management; however, studies integrating rainfall trend detection with homogeneity assessment are scarce in the Warangal district of Telangana, India. This study presents a comprehensive spatio-statistical analysis of long-term rainfall variability in the Warangal district of Telangana, using the Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) dataset. Annual rainfall data for the period 35 years (1990–2024) were extracted for 13 selected mandals. The descriptive statistics expose very sharp hydroclimatic contrasts where mean precipitation gradually changes from 977.91 mm in the southwestern stations to over 1217 mm in the northeastern sector. Descriptive statistical analysis was employed to characterize rainfall variability, while the non-parametric Mann–Kendall test and Sen’s slope estimator were used to detect monotonic trends. In addition, Pettitt’s, Standard Normal Homogeneity Test (SNHT) and Buishand Range tests were applied to identify abrupt shifts and evaluate rainfall homogeneity. The results reveal marked spatial variability in rainfall across the district, with a general increase in annual rainfall at maximum stations. Significant increasing trends were identified at several locations, accompanied by positive Sen’s slope estimates, indicating progressive rainfall intensification. Homogeneity analyses detected statistically significant change points, confirming that the rainfall series exhibits pronounced non-stationarity and a transition toward wetter conditions over recent decades. These findings demonstrate that rainfall variability in the region is driven by both gradual climatic trends and abrupt structural changes, highlighting the increasing complexity of regional hydroclimatic processes. The study provides the first integrated spatio-statistical assessment combining trend detection and multiple homogeneity tests for the Warangal district, offering a robust scientific basis for climate-resilient water resource planning, flood risk management, agricultural decision-making, and the revision of hydrological design standards under changing climate conditions.