Spatiotemporal Analysis of Precipitation in Hawaii Using High-Resolution Gridded Rainfall Data

Keywords: GIS, precipitation, Hawaii, climate change, rainfall, Mann-Kendall, Theil-Sen
Session Type: Virtual Poster Abstract
Day: Sunday
Session Start / End Time: 2/27/2022 03:40 PM (Eastern Time (US & Canada)) - 2/27/2022 05:00 PM (Eastern Time (US & Canada))
Room: Virtual 27

Abstract

In the state of Hawaii, extreme precipitation events, such as heavy rainfall and flooding, are increasing in frequency given the warming climate. Extreme precipitation events and their impacts are both economically and socially costly, making them important considerations in both climate change studies and policy. Previously, these events were examined at global, regional, and state levels. For Hawaii, indices for extreme precipitation events were previously studied from the 1950s to 2007 using daily station records. These indices include the simple daily intensity index (SDII) and the total number of days within a year with precipitation greater than or equal to 25.4 mm (R25), among others. The goal of this project is to calculate the above indices using a more spatially representative dataset from 1990 to 2014, as previous research focused on sparsely-distributed point data. SDII and R25 indices were calculated for the seven main Hawaiian Islands, and trends and significance were analyzed with the Mann-Kendall test and Theil-Sen Slope. Our research found a general decrease in both R25 and SDII across all of Hawaii for the study period. Spatial trends in R25 and SDII are similar across the study area. In other words, areas with an increasing (decreasing) R25 trend showed an increasing (decreasing) SDII trend. This means that Hawaii’s extreme rainfall days have become less intense and less frequent over this period, though more recent data are needed to confirm the longer-term trends.