SI-3C (12/1/04 version)
Overview, "As Is" Stream Integrity Situation: Stream Morphology
Assessing Stream Morphology
Stream morphology, or the size and shape of the stream, occurs because of a series of background conditions and complex processes that are difficult to describe simply.
However, there are key indicators that can be used to assess whether a stream channel is sustainable. These indicators provide data about the results of the force of running water on the landscape and the relative resistance the landscape offers to this force. If the exerted force is less than the resistance, there is no change. If, the force is greater than the resistance, there is change to the slope or stream channel. The science of measuring and analyzing these changes is known as geomorphology.
Significant changes in stream dimensions, discharge and pattern stem from dramatic changes in stream channel erosion or deposition within a short time period and indicate changes in flow (e.g. frequency and intensity of peak discharges) or sediment discharge. An understanding of stream morphology can help discern the causes of these changes in stream stability.
Current Status Of Stream Morphology Assessment In Ohio
Ohio does not currently have state-wide or watershed-wide data for the stressor indicators that are outlined in the stream morphology components section of the NPS Plan. There is data available for site specific projects and a wealth of guidance on how to conduct stream morphology assessments.
It is clear that a poor understanding of geomorphological processes, and inadequate consideration of the influence of changes to the landscape and floodplain, can cause a variety of adverse environmental outcomes, including water quality impairment. Therefore, Ohio EPA developed, and utilizes statewidem, the Qualitative Habitat Evaluation Index (QHEI) to "...describe attributes of physical habitat that may be important in explaining the species presence, absence, and composition of fish communities in a stream." QHEI is "... an approach that measures emergent properties of habitat (sinuosity, pool/riffle development) rather than the individual factors that shape these characters (current velocity, depth, substrate size)." For more explanation and background on QHEI see
The Qualitative Habitat Evaluation Index (QHEI): Rationale, Methods, and Application".
For more details regarding the linkage between QHEI and stream morphology assessment click here.
Ohio Stream Morphology Assessment Tools And Guidance
Nationally, there is increasing recognition of stream morphology assessment as a critical step in the process of determining practical approaches to stream restoration. Ohio first officially recognized stream morphology as fundamental to solving NPS problems in the 1999 Nonpoint Source Program Upgrade. Specifically, physical alterations to the stream channel and its corridor were included in the definition of NPS pollution and developing natural channel design procedures, training and demonstrations sites were recommended.
Since the 1999 recommendations were made, the following Ohio specific tools and guidance have been developed:
- A suite of standardized stream morphology assessment tools,
STREAM Modules, developed by the Ohio Department of Natural Resources and Ohio State University is available to assist resource managers and project planners.
- Ohio NRCS modified the national practice standard, Streambank and Shoreline Protection (580) (PDF 124kb), by emphasizing the importance of collecting basic stream morphology assessment information prior to planning and installing stabilization techniques. A corresponding "job sheet" is provided to assist planners with the collection of such information.