A Multiscale Conceptual Framework for Integrated Ecogeomorphological Research to Support Stream Naturalization in the Agricultural Midwest

Abstract

The complexity of fluvial systems necessitates interdisciplinary research in fluvial geomorphology and aquatic ecology to develop a fundamental understanding of interconnections among biotic and abiotic aspects of these systems. Integrated knowledge of this type is vital for environmental management of streams in human-dominated environments. A conceptual framework is presented for integrating geomorphological and ecological research on streams in East Central Illinois, USA, a glaciated low-relief agricultural landscape. The framework embodies a multiscale perspective in which a geomorphological conception of the fluvial system is used to define a hierarchy of characteristic spatial scales for exploring important linkages between stream geomorphology and aquatic ecology. The focus ecologically is on fish, because a rich body of historical information exists on fisheries in East Central Illinois and because past work has suggested that availability of physical habitat is a major factor influencing the community characteristics of fish in this human-altered environment. The hierarchy embodied in the framework includes the network, link, planform, bar unit, bar element, and bedform/grain scales. Background knowledge from past research is drawn upon to identify potential linkages between geomorphological and ecological conditions at each of these scales. The conceptual framework is useful for guiding integrated ecogeomorphological research at specific scales and across different scales. It also is helpful for illustrating how widespread human modification of streams has catastrophically altered the scalar structure of fluvial systems in East Central Illinois. Knowledge emerging from the integrated research provides a basis for environmental-management schemes directed toward stream naturalization.

Hydrology of channelized and natural headwater streams / Hydrologie de cours d'eau recalibrés et naturels de tête de bassin

“…Sparse data from studies conducted at a range of locations with varying climates suggest that channelization alters the natural flow regime, resulting in changes to response variables such as magnitude, frequency and rate of change. The most significant impacts of channelization are realized in headwater streams (Frothingham et al, 2002).…”

Use of Ecohydraulic-Based Mesohabitat Classification and Fish Species Traits for Stream Restoration Design

“…This classification scheme recognized the fluvial dynamics of a geomorphic bar unit by incorporating the Bar Unit Concept [36]. As a single geomorphic unit consisting of pool-riffle-bar morphology, the fluvial dynamics is characterized by a 3D convergent-divergent helical flow pattern [147,149,150,153].…”

“…Channel units are in the length scale of approximately 1-100 channel widths and reaches are 100-1000 channel widths [35]. In general for the Midwest US, planform types are classified as straight or meandering, and rarely braided [36]. Valley structure and floodplain-channel dynamics exert geomorphic controls on the channel by fixing the longitudinal gradient, and regulating the rate of sediment delivery to the channel.…”

“…When applying ecohydraulics to mesohabitat classification, it appears that there is a neglected ecohydrogeomorphic scale that occurs between the microhabitat and channel unit (pool-riffle) scales, as defined by the hierarchical habitat framework in Frissell et al (1986) [38]. Microhabitats are scaled to features on the stream bed <1 m, i.e., rocks, woody debris, macrophytes, etc., where channel units are scaled to geomorphic forms greater than 1-10 channel unit widths [35,36,260]. Relevant to fish use of habitat space and termed as a mesohabitats in this article, 3D hydraulic and turbulence patterns are scaled to large roughness elements (e.g., boulders, LWD) and a length dimension less than one channel unit width [160,261].…”

“…Biota distribution and abundance are governed by physical habitat structure spatially organized within a hierarchical structure and each subsequent scale consisting of geomorphic and ecological processes [34][35][36][37]. Frissell et al (1986) [38] describes the classic view of this hierarchical structure within a watershed from segment, reach, channel (pool-riffle) unit to the microhabitat channel bed scale.…”