River Basin Management

Environmental Flows

Regulation of streamflows due to the presence of dams is a growing concern to biologists, who argue that the reduction in natural flow variability negatively affects aquatic and terrestrial habitat. HydroLogics has considerable experience in addressing the tradeoffs between regulation for water supply or hydropower and the need for preserving or improving instream flows.  We have tested and recommended a wide variety of minimum reservoir release rules, including releases tied to a percent of the inflow, without compromising the reliability of the system in meeting drinking water needs. 

With OASIS, we can easily display a variety of flow measures, including frequency (probability distribution) plots which show the percent of time that flows exceed a certain threshold at certain times of year as defined by the stakeholders.  These may be contrasted with elevation or water supply shortage frequency plots, from which a balance can be struck between recreational users or water consumers concerned about lake levels and downstream users concerned about adequate rafting flows or suitable spawning conditions.  OASIS is linked with the popular Index of Hydrologic Alteration (IHA) software to provide users with a statistical flow assessment of alternative operating scenarios developed with OASIS. 

Related to environmental flows is water quality management, an area in which HydroLogics also has considerable experience.  We have developed and applied adaptive management strategies for temperature and salinity control, blending supplies to meet total dissolved solids targets in drinking water, and point and non-point source pollution control needed for developing total maximum daily loads (TMDLs). 

Click on the flyer to read about the cutting-edge integration of environmental flow assessments within OASIS.

"Through more intensive management, you freed up water for our instream flow needs without compromising water supply reliability."

Ridge Schuyler, former Director of the
Piedmont Program, The Nature Conservancy, Charlottesville, Virginia

© 2016 by HydroLogics