"Environmental flows describe the quantity, timing, and quality of water flows required to sustain freshwater and estuarine ecosystems and the human livelihoods and well-being that depend on these ecosystems" (Brisbane Declaration 2007, pdf). Although significant progress has been made in the last decade, the science of environmental flow management remains relatively young. In a review of 165 peer-reviewed studies, Poff and Zimmerman (2010) found that a majority of environmental flow work remains focused solely on flow magnitude rather than all components of the flow regime (magnitude, frequency, timing, duration, and rate of change, c. Poff et al. 1997). Moreover, there remains a focus on ecosystem structure (e.g., habitat) rather than ecosystem functions and processes (e.g., nutrient uptake, recruitment rates).
Environmental Flow Alternatives: Although the importance of “environmental” or “instream” flows is widely acknowledged, challenges arise in specifically identifying the flow regime needed to obtain a desired ecological state. Historically, environmental objectives were treated as a constraint whereby a minimum flow level for a given river is identified and used to maintain low flow conditions for critical needs. Although this provides some benefit, a minimum flow approach only addresses a single portion of a river’s flow regime (low flows). This document reviews multiple techniques aimed at managing water for environmental and ecological objectives (pdf, 1600KB).
Ecologically Effective Discharge: My disseration research seeks to expand available methods for connecting physical processes and ecological outcomes associated with environmental flow decision-making. Specifically, my commitee (Alan Covich, Mary Freeman, Rhett Jackson, and John Schramski) and I are developing a framework for determining ecologically significant flows in rivers using effective discharge analysis (Doyle et al. 2005). We are using a case study on the Middle Oconee River in Athens, Georgia to demonstrate the applicability of the proposed methods. Furthermore, we are examining a range of structural and functional parameters (e.g., habitat, recruitement rate, survival) for a variety of taxa (e.g., macroinvertebrates, submerged vegetation, fish) to determine response of the system as a whole rather than parts of the system in isolation.
Population Modeling of a Benthic Fish: I am also working with UGA ecologist Rachel Katz on a flow-dependent population model in the Middle Oconee River. We are coupling her long-term studies of Turquoise darter population dynamics with hydrologic data to examine changes in population abundance through time. Moreover, we are using this model to examine the potential effects of alternative water withdrawal schemes on the long-term persistence of this benthic fish (pdf, 170KB).
Drought awareness: Water managers must not only be able to respond to multiple competing needs (e.g., municipal water supply, recreation, ecosystem sustainability), but also must be ready to respond to climatic variability such as drought. Currently, Northest Georgia is in moderate to severe drought, and the local reservoir authority as responded accordingly. Although the authority has declared drought, local citizens seem to be somewhat unaware of the potential severity of a summer drought. To that end, Dr. Todd Rasmussen and I recently wrote an editorial for the Athens Banner Herald calling on the newspaper to publish drought status just as they publish weather forecasts (online version).
Historic Middle Oconee River levels in Athens, Georgia relative to 2012-drought conditions (Developed April 9, 2012).