Index of Hydrologic Alteration (IHA)
Tool Website: http://maps.tnc.org/tools.html#IHA
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. The software was developed to facilitate hydrologic analysis in an ecologically-meaningful manner. The program assesses many ecologically-relevant statistics derived from daily hydrologic data, including calculating the timing and maximum flow of each year's largest flood or lowest flows, and 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.
Not region specific
Measured or synthesized stream flow records
Many (67) ecologically-relevant statistics derived from daily hydrologic data
Linkage to Other Models
Level of Effort
Low. Software set up to be user friendly to import hydrology information and produce flow statistics.