| Popis: |
The current study aims to determine the variability and trend in rainfall data. From 1989 to 2018, daily rainfall data was gathered for the Shimsha basin, a sub-basin of the Cauvery basin in Karnataka, India, and aggregated into annual, seasonal, and monthly rainfall totals as well as the number of rainy days. In this study, the time series are subjected to statistical methods to examine rainfall variability and trend. The mean, standard deviation, skewness, kurtosis, coefficient of variation (CV), and Standardized Anomaly Index (SAI) are all used in the preliminary and variability analysis. To understand the rainfall distribution characteristics, Kurtosis and skewness were used. To identify homogenous and serially independent series, homogeneity and serial correlation tests were used. Mann–Kendall (MK) and Spearman's rank correlation (SRC) tests were performed to identify the trend in the homogenous and serially independent series. Sen's slope (SS) technique is applied to quantify the amount of the trend, and the Sequential Mann-Kendall (SQMK) test was used to assess the trend change point. The statistical tests indicated in this work were performed using open-source R packages such as "trend," "modifiedmk" and "trendchange". The study area's average rainfall was 801.86 mm, and CV ranges from 43.3–22.27%. The basin receives the highest rainfall in southwest monsoon season (SWM) followed by post-monsoon, summer, and winter seasons, respectively. Out of 162 series, 11-time series were found to be non-homogeneous and were omitted. Then out of 151 homogeneous series, 21 series showed a significant increasing trend while 99 and 31 series showed a little rising and declining trend, respectively. The study's results will help in water resource management, agricultural planning and socioeconomic development in the area. |
