Establishing Standards and Assessment Criteria for Ecological Instream Flow Needs in Agricultural Regions of Canada

Abstract

Agricultural land use can place heavy demands on regional water resources, strongly influencing the quantity and timing of water flows needed to sustain natural ecosystems. The effects of agricultural practices on streamflow conditions are multifaceted, as they also contribute to the severity of impacts arising from other stressors within the river ecosystem. Thus, river scientists need to determine the quantity of water required to sustain important aquatic ecosystem components and ecological services, to support wise apportionment of water for agricultural use. It is now apparent that arbitrarily defined minimum flows are inadequate for this task because the complex habitat requirements of the biota, which underpin the structure and function of a river ecosystem, are strongly influenced by predictable temporal variations in flow. We present an alternative framework for establishing a first-level, regional ecological instream flow needs standard based on adoption of the Indicators of Hydrologic Alteration/Range of Variability Approach as a broadly applicable hydrological assessment tool, coupling this to the Canadian Ecological Flow Index which assesses ecological responses to hydrological alteration. By explicitly incorporating a new field-based ecological assessment tool for small agricultural streams, we provide a necessary verification of altered hydrology that is broadly applicable within Canada and essential to ensure the continuous feedback between the application of flow management criteria and ecological condition.

The identification of hydrological indices for the characterization of macroinvertebrate community response to flow regime variability

“…Until relatively recently, the majority of environmental flow studies were primarily centred on components of the long-term flow duration curve considered to be important and relevant to in-stream ecology and habitats (Gao et al 2012, Peters et al 2012. The results of this research indicate that the influence of both long-and short-term antecedent Identification of hydrological indicesflow regime characteristics can be clearly identified using benthic community data and the LIFE score.…”

“…Although most legislation relating to the management of water resources and the protection of the riverine environment does not explicitly use the term "environmental flows" or "e-flows," it is widely recognized that the delivery or maintenance of an appropriate flow regime is essential for the sustainable management of riverine ecosystems (Poff et al 2010, Shenton et al 2012. As a result, national guidelines and legislation are increasingly recognizing the need for river flow targets that reflect the competing demands on finite hydrological resources (Arthington et al 2006, Acreman and Ferguson 2010, King and Brown 2010, Peters et al 2012, Shenton et al 2012.…”

“…These studies have subsequently been used to help define sustainable ecological/environmental flow regimes in regulated and anthropogenically modified rivers (Acreman et al 2008, Dunbar et al 2010b, Poff et al 2010, Peters et al 2012.…”

Cold-regions Hydrological Indicators of Change (CHIC) for ecological flow needs assessment

“…Monk et al (2012) initially explored and used additional flow-based cold-region specific indices relevant to the Athabasca River and downstream delta environments. This paper advances the work of Monk et al (2012) to be used in the EFN Framework proposed by Peters et al (2012a), which explicitly combines a "hydrological standard" with an "ecological performance indicator" to assess hydro-ecological deviations from a reference state for Canadian riverine systems.…”

“…Poff et al 2010, Peters et al 2012a. However, these approaches often fail to explicitly characterize the influence of winter ice cover and the spring freshet-key components of river systems in cold regions-on hydrological regimes and the associated water quality, aquatic habitat and ecology.…”