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Cooperative Institute for Research to Operations in Hydrology

CIROH Training and Developers Conference 2026 Abstract

Authors:  Savalan Naser NeisarySteven Burian – University of Alabama 

Presentation Type: Poster Presentation   

Title: Assessing the Relationship Between Reservoir Operations and Hydrological Drought Severity

Presentation Type: Poster Presentation

Abstract: Hydrological drought, defined as below-normal streamflow, is a complex extreme event that affects agriculture, hydropower, ecosystems, and water resources, particularly in the western United States. Although many studies have examined drought patterns and trends, limited research has focused on the relationship between water infrastructure operations, especially reservoirs, and hydrological drought characteristics such as severity, duration, and frequency at the local scale. In this study, we assess reservoir impacts on drought severity and frequency in the Great Salt Lake and Upper Colorado River Basins. We used the Python National Drought Analysis Tool (PyNdat), an open-source drought-frequency analysis package, to identify drought events and estimate drought characteristics using long-term average streamflow as the fixed threshold. Drought severity was compared across different durations and frequencies between upstream and downstream stations of 11 reservoirs. Results show statistically significant upstream–downstream differences, with mean differences in drought severity reaching up to 300%.