Use of quantitative habitat models for establishing performance metrics in river restoration planning

Abstract

The ecological effectiveness and success of river restoration strongly depend on the resources invested in planning. Unfortunately, this trend of restoration engineering is frequently compromised by the application of qualitative assessment and resource intensive adaptive management processes. Habitat simulation models are effective tools for selecting ecologically effective restoration measures as part of the Environmental Benefits Analysis. Through the support from a mesohabitat simulation model, we identified three habitat metrics: (1) Habitat Quantity Deficiency; (2) Alteration of Habitat Structure; and (3) Habitat Stress Days Alteration to quantify and visualize differences between restoration options in Restoration Alternatives Assessment diagram. This concept of quantifying habitat models is supported by an example of application in the Wekepeke Brook in Massachusetts, in which the habitat metrics were used to define quantitative benchmarks, goals and targets to guide the restoration process from the design to the evaluation phase. The three habitat metrics are a cost effective alternative for evaluating the ecological benefits of a planned action. The methodology contributes to a high potential for designing and monitoring restoration projects. Figure 4. Map of the Wekepeke Watershed (outlined) and study subwatershed (dashed) showing remnant impoundments from earlier waterworks infrastructure. 674 P. PARASIEWICZ et al.

Implementation of the Natural Flow Paradigm to Protect Dwarf Wedgemussel (Alasmidonta heterodon) in the Upper Delaware River

“…The alteration of HSD was used as an evaluation metric to compare between current conditions and simulated settings (Parasiewicz et al, 2012b). HSD is calculated as a cumulative duration of days where the persistent and catastrophic durations for selected thresholds have been exceeded.…”

“…geology, air temperature and biology), this manipulation may not sufficiently enhance habitat conditions to secure species survival and promote thriving aquatic communities, especially for rivers with heavily modified morphology. A more comprehensive way of implementing the NFP principles is through spatiotemporal habitat management that takes into account flows as well as hydro-morphology (Parasiewicz et al, 2012b). This can be accomplished with the help of habitat simulation models.…”

Habitat modeling in high‐gradient streams: the mesoscale approach and application

“…This analysis was based on the assumption that habitat is a limiting factor, and events occurring rarely in nature create stress to aquatic fauna and shape the community. Identification of HST considers not only the magnitude of an impact, but can also provide a means of quantitatively comparing duration and frequency of events, as well as different flow management scenarios (Parasiewicz et al 2012b, Vezza et al 2013a). To evaluate environmental thresholds, it was therefore essential to consider not only the magnitude of an impact, but also its duration and frequency.…”

Ecohydraulics: linkages between hydraulics, morphodynamics and ecological processes in rivers

“…(this issue) and Parasiewicz et al . (this issue) proposed metrics for quantitative assessment. These metrics are essentially based on the hypothesis that physical heterogeneity, mainly in flow depth and velocity, is an indicator of ecological integrity.…”