Environmental Flows: Managing Hydrological Environments

Abstract

Environmental flows refer to the facets of natural flow regimes that are required to sustain riparian and aquatic life in a healthy condition, plus provide for the needs of those human uses that rely on, and do not compromise, stream health values. Environmental flow assessments are required for regulated rivers, where the flow regime has been modified, or flow volumes significantly reduced. The methodological trend has been from narrow studies that catered for a single fish species at one critical life phase to a holistic approach that aims to restore natural river processes. Consideration has also been given to the specific issues of flood flows required for wetland inundation and channel formation, needs of groundwater‐dependent ecosystems, the needs of estuarine ecosystems, and flows required for recreational activities. Holistic methodologies are particularly appropriate in developing countries with strong livelihood dependencies on the goods and services provided by aquatic ecosystems. The number of studies worldwide that report environmental flow recommendations greatly outweighs the number of studies that report scientific evaluation of the results of implementation of these recommendations. However, where implemented environmental flow regimes have been monitored, the results have generally been positive.

The ecological limits of hydrologic alteration (ELOHA): a new framework for developing regional environmental flow standards

“…Approaches to linking flow regime alteration to habitat change are relatively well developed (Bovee et al. , 1998; Bowen, Bovee & Waddle, 2003;Pasternack, Wang & Merz, 2004; Crowder & Diplas, 2006; Jacobson & Galat, 2006), and they allow some inference about many ecological responses, albeit with some uncertainty (Tharme, 2003; Gippel, 2005). Flow–habitat linkages and their ecological consequences provide a core component of several existing environmental flow method (e.g.…”

Spatiotemporal topological kriging of runoff time series

“…For example, when assessing the hydropower potential one is interested in the flow duration curves of ungauged sites [e.g., Castellarin et al , 2004] and there is usually no need to vary rainfall characteristics. Another application is environmental flows where one is interested in the runoff dynamics and seasonality at ungauged sites without the need to examine scenarios [ Gippel , 2005]. For these applications, an alternative to the traditional rainfall‐runoff modeling approach may be to directly estimate the runoff time series from observed time series of neighboring catchments without recourse to rainfall data.…”