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DroughtIndices: Revised Surface Water Supply Index (SWSI)


Revised Surface Water Supply Index (SWSI) 

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Index Description

In the early 1990s the NRCS refined the SWSI calculation to improve upon the limitations of the existing SWSI procedures. This method substitutes streamflow forecasts for the weighting factor variables, which is an objective, statistical assessment of the data relating to snowmelt runoff.  Streamflow forecasts are optimized from the data for the hydrologic components and implicitly contain optimal weighting of the components. The revised technique provides a more stable month to month transition which eliminates some of the illogical shifts in index values, which the existing SWSI sometimes produces as the variables change throughout the year.

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Created at 11/15/2010 3:42 PM  by System Account 
Last modified at 11/16/2010 11:29 AM  by System Account