The NÖMORPH method and the Physical Habitat Characterization are both used to assess three primary zones of running waters: channel, riparian zone, and surroundings.
The task of the qualitative Austrian method is the description and the visual evaluation of the present hydromorphological status. This evaluation is based on the assignment of predefined parameters to condition classes (see 4.2.1.3 Evaluation). The American Physical Habitat Characterization is a mainly quantitative assessment method for site classification and trend interpretation including various measurements and calculations.
4.3.1 Goals of the Surveys
NÖMORPH- Goal: The NÖMORPH method (cf. freiland Umweltconsulting 2001) analyzes the deviation of the current status from the natural and characteristic status - the target state which is represented by reference conditions.
- Reference condition: Reference conditions or the potential natural status are derived from the river type region, the morphological river type, as well as the morphology and the vegetation of river, banks, and surroundings using information of historical maps if necessary.
Field of application:
- First report and basis for evaluation of aquatic ecology aspects in the course of water management projects.
- Planning principles for projects improving the ecological functionality, determination of the worthiness of protection of running waters, documentation of changes, etc..
- Illustration of correlations between structural water body condition and biological water quality.
Physical Habitat Characterization
- Goal: The Physical Habitat Characterization is a predominantly quantitative method for the assessment of physical habitat in streams. It focuses as much as possible on direct measures of physical properties of running waters that are most likely to have effects on biological communities respectively on the assessment of the relative importance of potential stressors on those communities.
- Reference condition: Because of the difficulty of estimating historical conditions for many indicators, least disturbed sites serve as reference sites.
Field of application:
- Report on the ecological conditions of streams and rivers.
- Identification and ranking of the relative importance of physical and biological disturbances affecting stream and river conditions.
carried out to illustrate additional habitat attributes and larger scales of physical habitat or human disturbance (cf. Stoddard et al. 2005).
“The Wadeable Streams Assessment (WSA) utilized data from EMAP-W and is now combined with a second continuative national survey of streams: the National Rivers and Streams Assessment (NRSA). Data are now being validated and analyzed, and the final NRSA report is expected in 2012” (USEPA 2011).
4.3.2 Mapped and Evaluated Criteria and Parameters
NÖMORPHThe NÖMORPH method describes hydromorphological attributes and evaluates predefined single parameters with the help of status classes (for attributes and parameters see Appendix B). These attributes and parameters are assigned to 5 “summarizing parameters”.
Based on these 5 “summarizing parameters” the ecomorphological status of a river section is assessed with regard to the reference conditions (cf. freiland Umweltconsulting 2001):
- Channel geometry and flow characteristics - Riverbed
- Connectivity water - land
- Banks respectively Riparian Zone - Vegetation
Spatial scale / Reach length:
The field work and the assessment is carried out using maps at a scale of 1:25,000 (ÖK 25).
A river is surveyed from mouth to source, as soon as one of the parameters changes (irrespective of the change of the numerical value of this parameter), a new sample reach begins. Again, all 5 summarizing parameters are assessed and estimated with the help of new forms. A river stretch has to be at least 100m long. Left and right banks are surveyed and assessed separately so that a stretch can be longer or shorter than the opposite stretch.
Physical Habitat Characterization
7 general physical habitat attributes (for individual parameters see Appendix B) are measured and estimated during the Physical Habitat Characterization procedure (cf.
Kaufmann et al. 1999):
- Stream Size - Channel Dimension - Channel Gradient
- Channel Substrate Size and Type
- Habitat Complexity and Cover for Aquatic Fauna - Riparian Vegetation Cover and Structure
- Anthropogenic Alterations and Disturbances - Channel - Riparian Interaction
Spatial scale / Reach length:
Surveyed stretches are chosen with the help of the „blue line stream“ – network, United States Geological Survey – maps on a scale of 1:100,000. For the better orientation in the field the location of the sampled reaches is marked with an X on 1:24,000-scale maps.
The length of sample reaches should be 40 times their low flow wetted width (at the time of sampling), but never less than 150m long to incorporate the local habitat-scale variation (e.g.,pools, riffles, meanders, etc.).
Detailed measurements and estimations are carried out at 11 transect positions that are set and flagged at 1/10th of the sample reach length, or four times the mean wetted channel width apart. Left and right banks are surveyed separately (cf. Peck et al. 2006).
4.3.3 Field Work
NÖMORPHThe mapping, that can be carried out by one experienced person, is executed during
“normal” or low flow conditions. In the field the plausibility of the developed reference conditions is controlled and adapted if necessary.
The field survey starts with the documentation of general data and basic information of the river stretch and its surroundings that are important for the orientation and the following assessment.
The second part of the field survey is divided into a describing part (characterization of summarizing parameters) and an evaluating part (evaluation of summarizing parameters using single parameters, see Table 23, cf. freiland Umweltconsulting 2001).
Physical Habitat Characterization
The best time for physical habitat characterization is a low flow season after leaf out and not closely following major flood events. The method is designed in such a way that a trained crew of two is able to survey a wadeable river stretch, regardless of whether it is broader than 10m and complex, within 4.5 hours. While one person makes the measurements in the channel, the other person records these measurements and does the visuals estimations and counts for the channel and its surroundings.
The survey starts with the measurements and estimations at the first cross-section at the downstream end of the sampling reach, transect A, and follows the river upstream to transect K including measurements between the transects (see Figure 6, cf. Kaufmann et al. 1999).
4.3.4 Evaluation
NÖMORPHEach of the 5 single summarizing parameters is evaluated with the help of 4 main water body condition classes and 3 intermediate condition classes. Condition class 1 stands for the best status, condition class 4 for the worst status. The condition class for one summarizing parameter is calculated using the mean evaluation for the single parameters (see Table 23).
The aggregated condition of a reach is the average of the condition of all 5 single summarizing parameters (cf. freiland Umweltconsulting 2001).
Condition classes:
- Condition class 4: very heavily modified condition
The condition classification of the NÖMORPH was transformed to the ecological status classification and the corresponding colour code of the Water Framework Directive (see Table 24).
Physical Habitat Characterization
Acquired data can be used for a multitude of calculations and evaluations (see 4.2.2 Physical Habitat Characterization, 6 Reference Conditions and Results, and 3.3.3 Environmental Monitoring and Assessment Program Western Pilot Study).
EMAP-W used chemical, physical and biological indicators to measure the stress to which streams and rivers are exposed. Concerning physical habitat the focus was on four specific stressors of physical habitat (streambed stability, habitat complexity, riparian vegetation, and riparian disturbance) and how they indicate levels of stress on aquatic organisms (relative extent and relative risk of stressors, cf. Stoddard et al. 2005).
Qualitative Physical Habitat Index (QTHP)
Hughes et al. (2010) executed and discussed four physical habitat indexes including the Stream Visual Assessment Protocol (SVAP) Version 2 of the Natural Resources Conservation Service, the Qualitative Habitat Evaluation Index (QHEI) of the Ohio Environmental Protection Agency, the Rapid Bioassessment Protocol (RBP) of the United States Environmental Protection Agency (USEPA), and a Qualitative Physical Habitat Index (QTHP) based on USEPA quantitative physical habitat measurements as applied for this work.
The QTPH is a qualitative index of channel and riparian habitat condition calculated from quantitative habitat measurements and visual cover estimates or tallies. The index evaluates the judged quality of the site with respect to eight dimensions of habitat structure, each represented as the mean of 2-11 separate scored metrics:
(a) Riparian vegetation (complexity, cover)
(b) Riparian disturbances (sum of proximity-weighted tallies of 11 types of disturbances) (c) Channel bed surface substrate (% silt, % sand, % fine gravel, % embeddedness, %
bedrock + hardpan, % macrophyte cover, % filamentous algae cover)
(d) Channel alteration (presence of pipes, revetment, or bed substrates composed of concrete or asphalt; relative bed stability; deviation from residual pool volume predicted from stream size and slope)
(e) Habitat volume (mean wetted width, mean channel cross-section area, mean residual depth, %dry channel)
(f) Channel spatial complexity (CV thalweg depth, CV wetted width, fish-macroinvertebrate cover variety)
(g) Cover magnitude (separate and sum of six cover types)
(h) Velocity and bed shear stress (mean slope, shear stress index)
Notes: Metric a = mean of subcomponents; metric b = mean of subcomponents; etc. for eight metrics.
For example, the first dimension, riparian vegetation, is calculated as the mean of scored metrics for riparian-structural complexity and cover. Before calculating the mean, the two subcomponent metrics were scored with respect to their influence on biotic assemblage integrity from 0 (‘‘lethal’’) to 1 (‘‘optimal’’), based on the collaborative professional judgement of four aquatic ecologists and four aquatic resource managers.
The total QTPH score is computed as the geometric mean of the eight scaled habitat dimensions, giving zero values to the total if only one of the dimensions is scored as lethal.
Like the metric scores, the QTPH index score for a site ranges from 0 (lethal) to 1.0 (optimal).
QTPH = (a b c d e f g h) (1/8) = geometric mean of subcomponents
4.3.5 Illustration and Documentation of the Results
NÖMORPHThe results of the NÖMORPH mapping were illustrated for whole river courses using maps (with a scale of 1:50000). The condition of the 5 single summarizing parameters was presented by means of tables and verbal description.
Data were integrated into the Wasserdatenverbund of Lower Austria - an information system for the recording, administration, and evaluation of data concerning water (cf. freiland Umweltconsulting 2001).
Physical Habitat Characterization
The Environmental Monitoring and Assessment Program Western Pilot Study (EMAP-W) presented the results of the Physical Habitat Characterization with the help of maps, graphs, tables, and verbal description.
For the presentation three different levels of geographic resolution were used:
- West-wide (12 states)
- Three major climatic/topographic regions – Mountains, Plains and Xeric
- Ten ecological regions – aggregated from Omernik Level III (Omernik 1987) ecoregions (cf. Stoddard et al. 2005)
5 Study Area
During the preparation phase of the thesis it became apparent to focus on one river system to get a consistent image after the evaluation and analysis of the data and the methods. As the field work could not be done within a few days due to weather conditions and time management, the watershed of the river Traisen was the first choice due to its proximity to Vienna and its reachability.
After studying the ÖK 50 maps and an inspection in the field, sites of four different headwaters and tributaries were chosen to be observed. The main decision criteria were on the one hand to get an overview of the variety of the Traisen river system concerning geology, altitude, morphological river types, valley shapes, stream orders and human alterations. On the other hand, the survey stretches had to be not too remote and moreover wadeable as the field work and the transportation of the equipment was done by only one person. Of special interest was the applicability of the methods for the assessment of residual water stretches.
The selected streams are all situated upstream of St.Pölten because there are hardly any major Traisen tributaries along the lower course. The four sites were subdivided into four reaches, each with a determined length of 150m to enable the comparison of the applied inventory methods.