Spatio-temporal rainfall analysis of Uttarakhand
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Date
2019-05
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Analysis of rainfall and rainy days are important issues for all mountainous states of India due to their varying topography and extreme rainfall events are the reason for quick surface runoff which is dangerous for safety of large structures and other natural resources. In this study,
spatial and temporal variability and trend of rainfall and rainy days was analyzed for Uttarakhand sate. Long-term characteristics of rainfall and rainy days were checked using statistical parameters. Mean, coefficient of variation, standard deviation and skewness in the rainfall and rainy days time series were checked on the seasonal and annual basis. Lag-1 serial autocorrelation using student’s t-test confirmed the randomness in the time series data and on the basis of t-test, Mann-Kendall (MMK) test and modified Mann-Kendall (MK) test has been used to analyze the trend in rainfall and rainy days data of all districts of Uttarakhand. Theil-Sen’s slope estimator method has been used to determine the magnitude of trend change and the percentage change over the study period. The change point in the trend and beginning of the change was detected using Sequential Mann-Kendall (SQMK) test. The inverse distance weighting (IDW) technique of interpolation in QGIS 3.4 has been
used for detecting the spatial variability and trend in rainfall and rainy days time-series. A moderate variation in annual rainfall and rainy days and high variation in seasonal rainfall and rainy days was observed in Uttarakhand. Both significant and non significant increasing and decreasing trends was obtained from the results depending upon the districts. A decreasing trend of rainfall and rainy days concentration was also observed in most of the districts on seasonal as well as annual basis. The analysis manifested the high spatial and temporal variability due to diverse precipitation-generating mechanisms and the need for an improved monitoring network.
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