Refinements in the Z-T method of extreme value analysis for small watersheds

Zelenhasic and Salvai (1987) described the "Z-T" method for determining recurrence intervals for streamflow droughts in a 8,800,000 ha river basin. That report is an extension of the work by Todorovic and Zelenhasic (1970). In this paper we will show that the Z-T method of drought analysis can be applied to a smaller (760 ha) basin if certain refinements are made. For small-sized catchments, one is more likely to find longer records for precipitation than streamflow. An objective of this study was to characterize a specific drought event in the Southern Appalachian Mountains of North Carolina with the Z-T method using both streamflow and long-term precipitation records.