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iha indicators of hydrologic alteration software download

Indicators of Hydrologic Alteration (IHA): Software for Understanding Hydrologic Changes in Ecologically-Relevant Terms
The Indicators of Hydrologic Alteration (IHA) is a software program that provides useful information for those trying to understand the hydrologic impacts of human activities or trying to develop environmental flow recommendations for water managers. Nearly 2,000 water resource managers, hydrologists, ecologists, researchers and policy makers from around the world have used this program to assess how rivers, lakes, and groundwater basins have been affected by human activities over time, or to evaluate future water management scenarios.

This program was developed by scientists at the Nature Conservancy to facilitate hydrologic analysis in an ecologically-meaningful manner. This software program assesses 67 ecologically-relevant statistics derived from daily hydrologic data. For instance, the IHA software can calculate the timing and maximum flow of each year's largest flood or lowest flows, then calculates the mean and variance of these values over some period of time. Comparative analysis can then help statistically describe how these patterns have changed for a particular river or lake, due to abrupt impacts such as dam construction, or more gradual trends associated with land- and water-use changes. The IHA software is described in a number of scientific papers.

Because software is inherently complex and may not be completely free of errors, it is your responsibility to verify your work and make backup copies, and TNC will not be responsible for your failure to do so. In no event will TNC be liable for indirect, special, incidental, or consequential damages arising from use of or inability to use this product, including, without limitation, damages or costs relating to the loss of profits, business goodwill, data or computer programs, even if advised of the possibility of such damages. The foregoing limitations shall not apply to claims relating to death or personal injury which arise out of products deemed to be consumer goods under applicable law. Some states do not allow the exclusion or limitation of implies warranties of limitation of liability for incidental or consequential damages, so the above exclusion or limitation may not apply to you.

Any commercial use of this software is prohibited without the express, written consent of TNC

Manual (English)

Manual (Spanish)


Tutorial (English)

Tutorial (Spanish)


Training (English)

Training (Spanish)


Publications & Other Documents

Richter, B.D., Baumgartner, J.V., Powell, J., and Braun, D.P., (1996). A method for assessing hydrologic alteration within ecosystems. Conservation Biology, 10(4), 1163-1174.

Posted to with permission from Blackwell Science, publisher of Conservation Biology.

Richter, B.D., Baumgartner, J.V., Wigington, R., and Braun, D.P. (1997). How much water does a river need? Freshwater Biology, 37, 231-249.

Posted to with permission from Blackwell Science, publisher of Freshwater Biology.

Richter, B.D., Baumgartner, J.V., Braun, D.P., and Powell, J. (1998). A spatial assessment of hydrologic alteration within a river network. Regulated Rivers: Research & Management, 14, 329-340.

Opperman, J. (2006). Preliminary IHA analysis for the Middle Fork Willamette River at Jasper OR.

Opperman, J. (2006). Indicators of Hydrologic Alteration analysis for the Patuca River.


IHA Application Database