Maximum likelihood logistic regression is used to estimate drought probabilities for selected Virginia rivers and streams 5 to 11 months in advance. Hydrologic drought streamflow probabilities for summer months are provided as functions of streamflows during the previous winter months. This application allows the display and query of these drought streamflow probabilities for Virginia streams.
Virginia drought streamflow symbology
Custom symbology developed for the Virginia Drought Streamflow Probabilities web tool. The symbology displays three summer month streamflow drought probabilities for each streamgage in the application (top, July; bottom-left, September; bottom-right August). The top circle (July) corresponds with the location of the physical streamgage and clicking on it displays site-specific streamgage and drought information. Drought probability values are shown using a color coded scale of 5 probability classes and a 6th no-data class.