In January of 2013, a symposium hosted by Delta Science Program and the UC Davis Center for Aquatic Biology and Aquaculture (CABA) titled, What is a Natural Hydrograph in Regulated Rivers? The Science of Natural Flows to the Delta, explored how the hydrologic regime of Delta inflows are impacted by land-use changes, diversions from the watershed, and climate change. These concepts are important since successful restoration in the Delta relies on restoring the physical processes within the landscape that will sustain chemical and biotic processes that support native biological community resilience.
However, in a highly modified landscape many of these changes are irreversible and the hydrologic response of the watershed is different from historic conditions. These differences are further compounded by the effects of climate change which affects total runoff, alters the inter-annual variability and increases the frequency of extreme events.
The extent to which physical processes and ecosystem functions can be recovered is an important question and is heavily influenced by the flow regime. But this poses the question of what is natural or even functional flow if the very landforms that historically shaped the hydrograph are now modified? Given these systemic changes, what do we mean by a natural hydrograph or unimpaired flows?
The symposium discussed various aspects of natural flows, functional flows, and unimpaired flows through a series of six presentations and a panel discussion. This symposium will be covered in four parts.
DR. GEOFFREY PETTS: In-stream Flow Science for Sustainable River Management
The plenary lecture was given by Dr. Geoffrey Petts, Vice-Chancellor of the University of Westminster, a position he has held since 2007. His research is at the interface of hydrology, geomorphology and ecology to address the sustainable development of water projects. He has published 20 books and more than 100 scientific papers, and is founder and Editor-in-Chief of the international journal River Research and Applications.
Dr. Petts began his presentation with a thought: “Are we really concerned with rivers flowing to the Delta, or are we talking about river flows for the Delta? The starting point is very important, because I think if you were starting with the question, what are the river flows that you need to sustain the functional development of the Delta and the transition zone, that’s a very different starting point and end point perhaps than talking about the functional flows in the regulated river.”
Coming up tomorrow: Coverage of the flows conference continues with a presentation by Chris Enright, “What do we mean by ‘natural functional Delta inflow in a regulated and modified system?” and Robin Grossinger with the presentation, “Toward the meaning of a natural hydrograph: Linking landscape and hydrograph.”