Indiana’s Water Shortage Plan was recently updated (2009) and established criteria to identify drought conditions and associated “Water Shortage Stages” designated as Normal, Watch, Warning, and Emergency. The three drought triggers are the 1-month Standardized Precipitation Index (SPI), U.S. Drought Monitor (USDM), and Percentage of Average Streamflow (28 streamflow gaging sites). The Water Shortage Stage is defined as Normal if no more than one indicator is outside of the normal range. The Water Shortage Identification Regions are the nine climate divisions determined by the National Weather Service. The drought triggers were tested during the dry conditions that occurred in Indiana late summer-fall of 2010. In general, the 1-month SPI and the USDM reflected fairly accurate conditions of surface dryness with groundwater-fed streamflow temporally lagging behind these indicators.
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