Published in JAWRA Journal of the American Water Resources Association
In an effort to restore predictable ecologically relevant spring snowmelt recession flow patterns in rivers regulated by dams, this study defined a methodology by which spring flow regimes can be modeled in regulated systems from the quantifiable characteristics of spring snowmelt recessions in unregulated rivers. An analysis of eight unregulated r...
Published in BioScience
Building on previous environmental flow discussions and a growing recognition that hydrogeomorphic processes are inherent in the ecological functionality and biodiversity of riverscapes, we propose a functional-flows approach to managing heavily modified rivers. The approach focuses on retaining specific process-based components of the hydrograph, ...
Over the past decade, the Natural Flow Regime paradigm has garnered widespread study, discussion and general acceptance in the scientific community as a guide for conservation, restoration and management of rivers. However, one fundamental aspect of the natural flow regime that has received little attention in both scientific study and resource man...
This technical report provides guidance for resource managers in considering conservation and restoration options for meadow ecosystems considering that the very foundation of meadow ecosystems\textemdashthe dynamic interplay of surface and ground waters supporting unique vegetation\textemdashwill likely change in time due to global atmospheric war...
Published in River Research and Applicatiions
Understanding the trade-offs between water for the environment and water for hydropower in regulated rivers can inform decision making about hydropower system planning, policy and operations, especially with anticipated climate warming\textendashinduced changes in runoff. This study used a multireservoir optimisation model to assess the hydropower ...
Published in Copeia
We explored the effects of large magnitude flow fluctuations in rivers with dams, commonly referred to as pulsed flows, on tadpoles of the lotic-breeding Foothill Yellow-legged Frog, Rana boylii. We quantified the velocity conditions in habitats occupied by tadpoles and then conducted experiments to assess the tolerance to values at the upper limit...
In many current hydropower project relicensing studies, instream flow assessment methods are used to evaluate flow effects and proposed flow prescriptions on fish. These techniques may be applicable to other sensitive aquatic species, such as the riverine-breeding Foothill Yellow-legged frog (Rana boylii). Two major components of flow modeling were...
Published in River Research and Applications
In regulated rivers, relicensing of hydropower projects can provide an opportunity to change flow regimes and reduce negative effects on sensitive aquatic biota. The volume of flow, timing and ramping rate of spring spills, and magnitude of aseasonal pulsed flows have potentially negative effects on the early life stages of amphibians, such as the ...
Published in BioScience
We present a conceptual model for the ecology of the spring snowmelt recession based on the natural flow regime that relates the quantifiable components of magnitude, timing, and rate of change to abiotic and biotic factors that govern riverine processes. We find that shifts in the magnitude of the recession largely affect abiotic channel condition...
Published in Geomorphology
The diversity of aquatic habitats in streams is linked to physical processes that act at various spatial and temporal scales. Two components of many that contribute to creating habitat heterogeneity in streams are the interaction between sediment supply and transport capacity and the presence of local in-stream structures, such as large woody debri...
Published in Herpetological Conservation and Biology
Four analytical approaches support the hypothesis that altered flow regimes, particularly spring and summer pulsed discharges, contribute to the decline of foothill yellow-legged frogs (Rana boylii) in regulated rivers. (1) A review of literature and FERC re-licensing reports indicates that egg masses are negatively affected by pulsed flows via sco...
Heterogeneity in physical habitat may be a key requirement for some riverine species to succeed in a naturally fluctuating flow environment; however, methods to quantify habitat heterogeneity in a manner relevant to the ecology of in-stream species are lacking. Spatial heterogeneity indices from landscape ecology are often applied on large-scale te...
