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This application allows the display and query of drought probability. Maximum likelihood logistic regression is used to estimate drought probabilities for selected Northeast region streams. Winter streamflows are used to estimate the chance of hydrologic drought during the summer months (July, August, and September) 5 to 11 months in advance.
Custom symbology was developed to display 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 seven probability classes and an eighth no-data class. The highest drought flow probability values from many equations range between 30% and 40%. A few equations have values approaching 100% drought flow probability. Only results from statistically significant relations are presented (p-value <= 0.05). Equations with p-values greater than 0.05 are identified as having no-data and are colored gray.
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.