A Century of Drought in HawaiModified Letter Turned Commai: Geospatial Analysis and Synthesis across Hydrological, Ecological, and Socioeconomic Scales

Drought is a prominent feature of HawaiModified Letter Turned Commai's climate. However, it has been over 30 years since the last comprehensive meteorological drought analysis, and recent drying trends have emphasized the need to better understand drought dynamics and multi-sector effects in HawaiModified Letter Turned Commai. Here, we provide a comprehensive synthesis of past drought effects in HawaiModified Letter Turned Commai that we integrate with geospatial analysis of drought characteristics using a newly developed 100-year (1920-2019) gridded Standardized Precipitation Index (SPI) dataset. The synthesis examines past droughts classified into five categories: Meteorological, agricultural, hydrological, ecological, and socioeconomic drought. Results show that drought duration and magnitude have increased significantly, consistent with trends found in other Pacific Islands. We found that most droughts were associated with El Nino events, and the two worst droughts of the past century were multi-year events occurring in 1998-2002 and 2007-2014. The former event was most severe on the islands of O'ahu and Kaua'i while the latter event was most severe on HawaiModified Letter Turned Commai Island. Within islands, we found different spatial patterns depending on leeward versus windward contrasts. Droughts have resulted in over $80 million in agricultural relief since 1996 and have increased wildfire risk, especially during El Nino years. In addition to providing the historical context needed to better understand future drought projections and to develop effective policies and management strategies to protect natural, cultural, hydrological, and agricultural resources, this work provides a framework for conducting drought analyses in other tropical island systems, especially those with a complex topography and strong climatic gradients.