Foundational elements for developing a United States Caribbean Streamflow Duration Assessment Method

Water resource managers need Streamflow Duration Assessment Methods (SDAMs) to predict if streams are ephemeral, intermittent, or perennial. Although SDAMs exist for some regions of the United States of America (U.S.), no validated SDAM has been developed for Puerto Rico and the U.S. Virgin Islands. This review lays the foundation for a U.S. Caribbean SDAM that will be accurate and practical by characterizing trends in stream research and identifying flow class documentation, candidate indicators of streamflow duration, and a hydrogeographic framework. We screened 2081 titles and abstracts and 750 full-text documents. Despite many Caribbean islands having only non-perennial streams or a mixture of perennial and non-perennial streams, our review identified only 10 studies that evaluated stream characteristics between reaches with different flow duration. Candidate indicators include drainage area, riparian herbaceous cover, two fish metrics, and 19 aquatic invertebrate metrics. A total of 235 documents provided localities for 2282 stream reaches, 94.7% in Puerto Rico and 5.3% in the U.S. Virgin Islands. Eighty-two documents classified streamflow duration, but only 45 provided flow class and locality. From these, we identified 425 candidate SDAM study reaches, of which 308, 103, and 14 were perennial, intermittent, and ephemeral, respectively. Hydrology, chemistry, and geomorphology topics dominated the stream research literature. The ecological life zones framework is the most suitable of thirteen hydrogeographic frameworks for a U.S. Caribbean SDAM. The subtropical dry forest zone contained most of the documented intermittent reaches, while documented perennial reaches dominated the subtropical moist forest and subtropical wet forest zones.