Cooperative Fish and Wildlife Research Units Program: Arkansas
Education, Research and Technical Assistance for Managing Our Natural Resources

Hydrologic alteration is an important issue affecting stream ecosystems globally. Effects of flow alteration are likely to vary temporally and to be flow regime dependent. We examined flow alteration in seven natural flow regimes of the Interior Highlands, USA: Groundwater Stable, Groundwater, Groundwater Flashy, Perennial Runoff, Runoff Flashy, Intermittent Runoff and Intermittent Flashy. We estimated flow alteration (observed/expected) at 175 sites with U.S. Geological Survey stream gages for each of 171 hydrologic metrics in the categories of magnitude, frequency, duration, timing and rate of change. Temporal variation in flow alteration was examined and related to factors such as climate change. Flow alteration patterns in flow regimes will be compared with a focus on intermittent versus perennial streams. We found that reductions in flow were more common than flow increases and significant reductions in flow were more common in intermittent than perennial streams. Altered hydrology is likely to affect ecosystem structure and function of intermittent streams and may influence the vital role these streams play in material transport and biological connectivity.