CIVE 633 - ENVIRONMENTAL HYDROLOGY

THE RIVER CONTINUUM CONCEPT

  • There is a difference between small rivers (streams) and large rivers from the ecological perspective.

  • The ecological perspective includes productivity (primary and secondary), carbon dynamics, nutrient cycling, biodiversity, hydrologic interactions, hydraulic effects.

  • Dams, lakes and swamps separate rivers into reaches with different ecological characteristics.

  • Large rivers have frequent transversal interactions with the flood plain, which small rivers don't have.
The River Continuum Concept (RCC)

  • The RCC treats the river network as a continuous series of physical, chemical and biological adjustments along the length of the river, and uses a stream in a temperate climate as an example of application.

  • RCC views rivers as longitudinal elements, in which the processes in downstrem reaches are linked to those in the upstream reaches.

  • The conceptual model has been criticized because rivers may not have a continuous ecological behavior from headwaters to sea.

  • Can the RCC explain the behavior of large rivers? Are large rivers longitudinally continuous from an ecological standpoint?
RCC, GEOMORPHOLOGY AND RIVER-FOREST INTERACTIONS

  • The RCC provides the most useful predictions of longitudinal lotic ecosystem characteristics for river systems with geological constraints.

  • Where there is interaction with the flood plain, the prediction is not as good.

  • The amount of flood plain interaction is constrained by geology and geomorphology.

  • Large variability of depths, widths and velocities lead to increased productivity, and better developed trophic chains.

  • The RCC is of limited value for predicting large river ecosystem function.

  • The research challenge is to determine how ecologically important processes at the reach level can be meaningfully aggregated to large river systems.

  • Interaction between the disciplines (ecologists, fisheries biologists, biogeochemists, atmospheric scientists, engineers, geomorphologists, and hydrologists) is the present challenge.

 
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