Drought or Wet Assessment of Daily Rainfall Pattern of the Budhi Gandaki River Basin, Nepal: Standardized Precipitation Index Approach using Probabilistic Model

Abstract

Background: Rainfall is a natural phenomenon. Dramatic changes in the rainfall pattern lead to extreme climatic or hydrological events like flash floods, or floods, landslides or severe drought events at any parts of the world.

Objective: The objective of this study aims to perform analysis of drought/ wet for fifteen meteorological /hydrological stations distributed over the Budhi Gandaki River Basin, Nepal.

Materials and Methods: The Kolmogorov-Simonov test, Anderson-Darling test and Chi-square test are used for testing of the hypothesis of goodness of fit supported by the q-q plot (or p-p plot), cumulative distribution function plot and probability density function plot. The standardized precipitation index is a widely used to develop the index to monitor the dryness/wetness in a given day.

Results: Johnson SB distribution and Weibull distribution were fitted to the daily rainfall across the fifteen stations.

Conclusion: There were some episodes of moderate drought events across six stations. Similarly, there were a moderate type of wetness across five stations. The rest of the stations had a majority of near normal days out of 13514 days.

Supplementary Material avialable here https://doi.org/10.3126/njs.v4i0.33499