Arizona Long-term Drought Status Reporting
Monitoring drought status is the backbone of Arizona’s Department of Water Resources (ADWR) Drought Preparedness Plan. ADWR produces a quarterly long-term drought status map and summary based on weekly input from Arizona Drought Monitoring committee (Figure 2). ADWR also generates a monthly commentary that summarizes the four drought status maps issued each month by the US Drought Monitor. Drought statuses are determined at the watershed level.
ADWR’s calculates long-term drought status by comparing the 24-, 36- and 48-month precipitation and streamflow totals to all these same periods in the previous 30-year record. Therefore, only gages with a 30-year record of data are used. If precipitation and streamflow are less than the 40th percentile, meaning 40 percent of the time values for the 24-, 36-, and 48-month period in the last 30 years are equal to or less than the current period value, than conditions are classified as abnormally dry or worse. This method has been applied to other regions with success.