An Assessment of Extreme Precipitation Trends in the Missouri River Basin: Insights From Three Gridded Precipitation Data Sets and Climate Indices

Abstract

This study investigates the changing characteristics of extreme precipitation indices in the Missouri River Basin (MORB) from 1981 to 2022, utilizing three well‐known gridded daily precipitation datasets: CHIRPS, CPC, and ERA‐5. Employing the Expert Team on Climate Change Detection and Indices (ETCCDI) climate indices and the Mann‐Kendall test, the study analyzes MORB mean and extreme precipitation characteristics. Across the three datasets, ERA‐5 and CPC exhibited closer agreement in capturing basin‐wide mean precipitation, as compared to CHIRPS data. Results indicate a consistent increase in extreme precipitation, particularly in the southern MORB, with total precipitation showing an upward trend across MORB. Annual maximum 1‐day precipitation (Rx1 day) exhibits both positive and negative trends, but positive trends dominate, while the Annual maximum consecutive 3‐day precipitation (Rx3 day) and Annual maximum consecutive 5‐day precipitation (Rx5 day) indices show positive trends, suggesting an enhanced risk of large floods. Return Level (RL) values are obtained by employing the Gumbel distribution to model annual daily maximum precipitation considering two different historical time periods. The analysis of differences in daily annual maximum RLs showed a significant increase in precipitation magnitudes between recent and historic periods. This indicates that extreme precipitation events of a given frequency are now associated with larger precipitation totals, implying that storms of a given magnitude are occurring more frequently in recent decades. A larger positive trend is observed in the average intensity of precipitation as assessed by the Simple Daily Intensity Index (SDII), and the annual total precipitation on days with precipitation exceeding the 95th percentile (R95 pTOT) in the southern MORB. The findings of this study are useful for informing flood risk management, water resource planning, agricultural sustainability, and climate change adaptation in the Missouri River Basin.

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