Trends and homogeneity of monthly, seasonal, and annual rainfall over arid region of Rajasthan, India

• Published in: Theoretical and applied climatology 2019-05, Vol.136 (3-4), p.795-811
• Main Authors: Meena, Hari Mohan, Machiwal, Deepesh, Santra, Priyabrata, Moharana, Pratap Chandra, Singh, D. V.
• Format: Article
• Language: English
• Subjects: Agricultural management; Agricultural resources; Agricultural water supply; Agriculture; Annual; Annual rainfall; Annual variations; Aquatic Pollution; Arid regions; Arid zones; Atmospheric Protection/Air Quality Control/Air Pollution; Atmospheric Sciences; Climate science; Climatology; Coefficient of variation; Earth and Environmental Science; Earth Sciences; Homogeneity; India; Interannual variability; Mean annual precipitation; Monsoon rainfall; Monsoons; Monthly; Original Paper; Outliers (statistics); Precipitation variability; Rain; Rainfall; Rainfall trends; Rainfall variability; Regional planning; Seasons; Stations; Statistical analysis; Statistical significance; Temporal variations; Trends; Waste Water Technology; Water; Water Management; Water Pollution Control; Water resource management; Water resources; Water resources management; Wind
• ISSN: 0177-798X; 1434-4483
• DOI: 10.1007/s00704-018-2510-9

Knowledge of rainfall variability is important for regional-scale planning and management of water resources in agriculture. This study explores spatio-temporal variations, trends, and homogeneity in monthly, seasonal, and annual rainfall series of 62 stations located in arid region of Rajasthan, India using 55 year (1957–2011) data. Box-whisker plots indicate presence of outliers and extremes in annual rainfall, which made the distribution of annual rainfall right-skewed. Mean and coefficient of variation (CV) of rainfall reveals a high inter-annual variability (CV > 200%) in the western portion where the mean annual rainfall is very low. A general gradient of the mean monthly, seasonal, and annual rainfall is visible from northwest to southeast direction, which is orthogonal to the gradient of CV. The Sen’s innovative trend test is found over-sensitive in evaluating statistical significance of the rainfall trends, while the Mann-Kendall test identifies significantly increasing rainfall trends in June and September. Rainfall in July shows prominently decreasing trends although none of them are found statistically significant. Monsoon and annual rainfall show significantly increasing trends at only four stations. The magnitude of trends indicates that the rainfall is increasing at a mean rate of 1.11, 2.85, and 2.89 mm year −1 in August, monsoon season, and annual series. The rainfall is found homogeneous over most of the area except for few stations situated in the eastern and northwest portions where significantly increasing trends are observed. Findings of this study indicate that there are few increasing trends in rainfall of this Indian arid region.