Stream Corridor Assessments

HDSS takes the guesswork out of mitigation planning.
Do you ever feel that waterway project decisions that are based on limited data might be missing important issues? Decisions based on traditional site-based stream assessments are relying on intensive reviews of short stream stretches while the majority of the stream remains unseen. HDSS Stream Corridor Assessments encompass 100% of a stream corridor with geo-referenced video and data. The result is a much better understanding of factors that are impacting a stream for better mitigation planning.

Our Methodolgy
Trutta’s High Definition Stream Surveys produce comprehensive stream corridor assessments that rapidly identify areas in greatest need of restoration or conservation. By providing continuous 1-meter longitudinal resolution of stream corridor conditions, HDSS gives planners the documentation they need to make more informed decisions.

As shown in Figure 1, the HDSS framework consists of six fundamental elements:

Figure 1 Above. Elements of the Stream Corridor Assessment framework evaluated using the high definition stream survey technique. Discreate features are  located within the corridor and can affect the stream form and function, most often along the streambanks or streambed.

  • Streambed, Right streambank, Left streambank, Right riparian area, Left riparian area: These first 5 elements are Continuous Data.
  • Discrete features (Point data): Man-made items (pipes, road crossings) or other discrete features of environmental importance (large woody debris) are Point Data, and can occur anywhere in the corridor.

When combined, Continuous Data and Point Data define the location, extent and condition of issues within the stream corridor to aid in planning and effective management. Additionally, each element can be used independently to identify and target specific management actions.
HDSS produces large volumes of detailed video and data that support Mitigation Prioritization, Integrated Planning, and Impact Assessments. The high-definition video of the stream corridor can be linked to a database of information that is easily mapped in GIS software.

HDSS links video, data, and maps in one system. The video footage of this pipe crossing a stream is more informative than a description of a dot on a map.

Poor stream bank conditions, an example of a Contiuous variable.

Tires in the water, an example of a Discrete Feature, or Point variable. Knowing the locations of trash relative to access points can help prioritize stream clean-up efforts.

A logjam, another example of a Discrete Feature. Logjams are typically found downstream of unstable bank areas.

HDSS provides planners and managers with a comprehensive approach to understanding existing conditions throughout an entire stream corridor. HDSS will produce more accurate impact assessments and result in more effective integrated watershed planning, predictive modeling, and mitigation planning and prioritization. HDSS is also ideal for fulfilling permitting and compliance requirements, such as replacing the traditional Streamwalk survey (i.e., Visual Stream Survey and Impairment Inventory) of the MS4 permitting process.

Streambank Erosion Susceptibility

A High Definition Stream Survey will quickly identify and rank your bank erosion problems.
Do you know the precise locations of the top 10 worst erosion problems in your streams? Ranking bank erosion problems doesn’t have to be a complex and expensive undertaking involving soil sampling, extremely precise bank heights and slope measurements, and root mass analyses. HDSS is a peer-reviewed technique that quickly and accurately assigns erosion scores over long sections of waterway, backed up by video documentation. Planners can get complete erosion documentation of their waterway earlier for more timely mitigation planning.

Our Methodology
Streambank condition reflects the susceptibility of the streambank to the erosive forces of water (streambanks in good condition are less likely to erode and fall into the stream than ones in poor condition). Streambank Erosion Susceptibility scoring involves a quick and accurate visual assessment of streambank cover, height, slope, soil, and riparian condition and enables us to predict potential erosion at high flows.


HDSS video documentation can be accessed to see actual conditions anywhere along a stream corridor.

HDSS techniques will provide accurate bank erosion analyses over longer stretches of stream in a shorter period of time than is possible using traditional methods. HDSS video documentation also allows for third party verification and validation of erosion scoring before remediation project decisions are made. HDSS erosion scoring is based on standard bank erosion indices but can be adapted to accommodate other parameters if necessary.

The images below show representative levels of bank classification that were documented using an HDSS kayak setup.

Impact Assessments

High Definition Stream Survey techniques enable measurable results.
Can you easily measure and clearly show and explain the impacts of your waterway projects to others? Inadequate or inaccurate pre- and post-construction data makes it very difficult to determine the success of your waterway project. HDSS techniques resolve this by providing you with comprehensive, geo-referenced data both upstream and downstream from a mitigation site. You’ll end up with measureable results and a clearer understanding of what worked and what didn’t for better future investment decisions.

Our Methodology
HDSS involves the continous documentation of geo-referenced stream corridor data over long stretches of waterway. HDSS is a faster and more comprehensive data collection technique than traditional site-based assessment methods. Video and sensory data is compiled and analyzed using our proprietary software system. Conclusions and recommendations can be tailored into reports that meet the needs of different stakeholders. The baseline information is reviewable so clarifications or interpretation validations are easy.

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