8. Monitoring Timescales

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8.1 Monitoring – for how long?

Deciding when to complete your monitoring (i.e. which season) and how many times you collect data each year is an essential aspect towards achieving effective monitoring. Each aspect to be monitored must relate back to the project objectives to ensure these will be answered. The detail and frequency of sampling is to some extent, a matter of expert judgement and dependant on questions required to be answered. Flexibility is key to good monitoring; not all elements need to be monitored during the same year and timing may vary depending on specific weather conditions. It must be considered, however, that many methods must be carried out at a particular time of year. The table shown in Table 8.1 designed by Woolsey et al. (2007) highlight the need to consider the overall length of monitoring; in some case change may still be detectably up to 15 years after project completion.

Table 8.1: Relevant timescales for monitoring indicators of river restoration success, from Woolsey et al., 2007

Indicator category Indicator Number of years after which survey can take place
Project acceptance Acceptance by interest group* 1-15
Acceptance by entire public* 1-15
Acceptance by project work group* 1-15
Stakeholder participation Satisfication of interest groups with the design of the participation process 1-5
Satisfaction of the public with participation opportunities 1-5
Satisfaction of interest groups with participation opportunities 1-5
Recreational use Number of visitors 1-15
Variety of recreational opportunities* 1-15
Public site accessibility for recreation 1-15
Landscape Diversity and spatial arrangement of habitat types* 3-15
Aesthetic landscape value* 1-15
Longitudinal connectivity Barrier free migration routes for fish| 1-5
Hydromorphology and Hydraulics Inundation dynamics: duration, frequency and extent of flooding 1-15
Variability of measured channel width 1-15
Variability of visually estimated wetted channel width* 1-15
Variability of flow velocity 1-15
Depth variability at bank-full discharge 1-15
Bedload Bedload regime 1-15
Organic material Short-term leaf retention capacity 1-15
Quantity of large wood 1-15
Quantity and composition of floating organic matter and abundance and diversity of colonizing snails 1-5
River bed Permeability of river bed 3-15
Diversity of geomorphic river bed structures* 1-15
Temporal changes in diversity of geomorphic river bed structures* 1-15
Clogging of hyporheic sediments 1-15
Grain-sized distribution of substratum* 1-15
Degree and type of anthropogenic modification 1-15
Indicator category Indicator Number of years after which survey can take place
Shore Width and depth of naturalness (vegetation, composition of ground) of riparian zone 1-15
Quantity and spatial extent of morphological units 1-15
Temporal changes in the quantity and spatial extent of morphological units| 1-15
Shoreline length 1-15
Degree and type of anthropogenic modification 1-15
Transition zones Food subsidies across land-water boundaries 1-2
Exchange of dissolved nutrients and other solutes between river and groundwater 3-15
Community composition and density of small mammals on floodplain 1-15
Refugia Availability of three types of refugia (hyporheic refugia, shoreline habitats, and intact tributaries 1-5
Temperature Spatial and temporal variation in water temperature* 1-15
Fish Age structure of fish population 1-15
Fish species abundance and dominance 1-15
Diversity of ecological guilds of fish 1-15
Fish habitat Presence of cover and instream structures 1-15
Macroinvertebrates Richness and density of terrestrial riparian arthropods 1-5
Occurance of both surface water and groundwater organisms in the hyporheic zone 1-15
Taxonomic composition of macroinvertebrate community 1-15
Presence of amphibiontic species in the groundwater 1-15
Vegetation Presence of typical floodplain species 1-15
Succession and rejuvenation of plant species on floodplains* 3-15
Temporal shift in the mosaic of floodplain vegetation categories 3-15
Composition of floodplain plant communities 1-15

8.2 Monitoring – which season to collect data?

Table 8.2 provides a summary of when is the optimum time (A) and possible time (B) to carry out surveys for rivers and wetlands/floodplains for a range of functional groups and where important for different parts of the life cycle. Whether you then decide to move you morphological measures to optimise you ecological interests of vice versa depends very much on you initial objectives (i.e. do you need to assess the degree of morphological change and generic habitats that are forming or are you more interested in what species are present and how where they are colonising?).

Table 8.2: Timescales for different sampling types (A = optimum time B = possible time).
Year Season Ecology Fisheries (salmonids) Fisheries (Cyprinids) Geomorphology Hydrology Macrophytes
Year 1 Spring (A) Rivers (A) eggs/fry (A)
Summer (A) Wetlands (B) eggs/fry (A) fry/adults (A) (A) (A)
Autumn (A) Rivers (A) juveniles (A) adults (A) (B)
Winter (A) adult/spawning (B) (A)
Year 2 Spring (A) eggs/fry (B) (A) (A)
Summer (B) eggs/fry (A) (A) (B)
Autumn (A) juveniles (A)
Winter (A) adult/spawning (A)
Year 3 Spring (A) Rivers (A) eggs/fry (A)
Summer (A) Wetlands (B) eggs/fry (A) (A) (A)
Autumn (A) Rivers (A) juveniles (A) (B)
Winter (A) adult/spawning (A)
Year 4 Spring (A)
Summer (A)
Autumn (B) (A)
Winter (A)
Year 5 Spring (A) Rivers (A) eggs/fry (A)
Summer (A) Wetlands (B) eggs/fry (A) (A)
Autumn (A) Rivers (A) juveniles (A) (B)
Winter (A) adult/spawning (A)
Year 6 Spring (A) eggs/fry (B) (A)
Summer (B) eggs/fry (A) (A)
Autumn (A) juveniles (B) (A)
Winter (A) adult/spawning (A)
Year 7 Spring (A) Rivers (A) eggs/fry (A)
Summer (A) Wetlands (B) eggs/fry (A) (B)
Autumn (A) Rivers (A) juveniles (A) (B)
Winter (A) adult/spawning (A)
Year 8 Spring (A)
Summer (A)
Autumn (A)
Winter (B) (A)
Year 9 Spring (A) eggs/fry (B) (A)
Summer (B) eggs/fry (B) (A) (A) (A)
Autumn (A) juveniles (A) (A) (B)
Winter (A) adult/spawning (A)
Year 10 Spring (A) Rivers (A)
Summer (A) Wetlands (A)
Autumn (A) Rivers (A)
Winter (A)

Notes:
Geomorphology may need flexibility to account for high and low flows depending on objectives set.
Invertebrates can be flexible to be timed after geomorphology has adjusted

8.3 Key timescale considerations

It is important to note the following:

  • Not all aspects of river restoration record success at the same period of time (i.e. recovery period may vary between species, river types and geographical location). Both limitations on movement of sediment and abundance and diversity of species can have significant effects on both ecological and physical recovery rates.
  • The rate of recovery will vary depending on the local weather conditions; a year of drought may limit invertebrate or macrophyte recovery as shown in the STREAM case study (see Section 11.4); conversely, an extreme flood event may result in a more rapid than predicted change in plan and cross sectional form the predicted.
  • The time at which it is most appropriate to monitor varies depending on species, life cycle aspect required to capture and flow event variability.

Aim to design your monitoring strategy to be flexible in terms of detail collected and frequency. This will depend initial objectives, fluctuations in seasonal conditions from year to year, your river type, its hydrological regime and the ecological communities present.