Geomorphic context in rivers

Abstract

Geomorphic context refers to the geomorphic setting of a river reach, which is defined as a length of river with consistent valley and channel geometry. Context includes spatial dimensions of geometry, location within a drainage basin, and location within a global context. Context also includes temporal dimensions of the frequency and duration of specific processes influencing the river reach and the historical sequence of natural and human-induced processes that continue to influence process and form in the river reach. These spatial and temporal characteristics interact to create a geomorphic context that governs the contemporary form of the river corridor, the rates and processes by which diverse materials move through the corridor, and the adjustments of form and process in response to disturbances. Context matters for both basic understanding and effective management of river corridors. Examples of widely used formal articulations of geomorphic context include a bedform-based classification of mountain streams, geomorphic process domains, and river styles. Each has been applied to understanding and predicting longitudinal variations in stream power, sediment budgets, habitat and biotic communities, resilience to disturbance, and other characteristics of rivers. The three Cs of rivers—complexity (or spatial heterogeneity), connectivity, and context—provide a conceptual framework for river research and management.