Welcome to the rapidly growing community of Indicators of Hydrologic Alteration
(IHA) software users! This software has been developed by The Nature
Conservancy (TNC) as an easy-to-use tool for calculating the characteristics of
natural and altered hydrologic regimes. The method and software will work on any
type of daily hydrologic data, such as streamflows, river stages, ground water
levels, or lake levels. The power of the IHA method is that it can be used to
summarize long periods of daily hydrologic data into a much more manageable
series of ecologically relevant hydrologic parameters.