Welcome to Conservation Gateway

The Gateway is for the conservation practitioner, scientist and decision-maker. Here we share the best and most up-to-date information we use to inform our work at The Nature Conservancy.

Indicators of Hydrologic Alteration Version 7.1: User's Manual

The Nature Conservancy

This is a user manual for the Indicators of Hydrologic Alteration software (Version 7.1). The 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.