The citizen River Habitat Survey (cRHS) is based on a survey methodology developed in the 1990s that has been used to assess the quality of river habitats in the UK and in parts of Europe, River Habitat Survey (RHS).

RHS is a method designed to characterise and assess, in broad terms, the physical structure of freshwater streams and rivers. The field survey element does not require specialist morphological or botanical expertise, but recognition of vegetation types and an understanding of basic river morphology and processes are needed.

RHS and cRHS is carried out along a standard 500m length of river channel. Observations are made at ten equally spaced spot-checks along the channel, whilst information on valley form and land-use in the river corridor provides additional context.

The underlying need for any observational method such as RHS is confidence in the survey data. This means consistent recording of features by competent, well-trained surveyors as well as checks on subsequent data-entry onto the computer database.

The field survey was designed, tested and improved as a result of extensive use on rivers in the UK since 1994. The latest version of the survey methodology and associated manual were released in 2003 and can be found on the website.

The survey was applied to more than 25,000 sites in the UK and many more in other parts of the world such as Spain, Portugal, Italy, Greece, Poland, Slovenia etc. All RHS sites are contained in the RHS database along with photos and videos.

With the growing participation of volunteers in river management and monitoring and the development of citizen science, it was decided to develop a simplified version of the RHS for use by non-specialists following less intensive training.

The Citizen River Habitat Survey (cRHS) is designed to be used on its own by Citizen Scientists or as part of a collaboration and knowledge exchange with more expert RHS surveyors. The information collected using cRHS can be inputted into a database and completed by certified RHS surveyors using the provided photographic and video evidence. This way, 95% of a standard RHS information can be collected and analysed.

Using cRHS, it will be possible to collect a wide range of site data and analyse them within the context of data collected as part of previous national surveys since 1994.

Scope of the manual

Guidance is provided on the fieldwork survey element of the core RHS method only. It does not cover map-based information gathering or the collection of additional information by certified surveyors following the survey.

The manual does not detail how to undertake preparatory work prior to a survey, gaining landowner permission, or how to link cRHS to other surveys that may be carried out in tandem with cRHS. All these aspects need to be planned and agreed between the commissioning organisation and the surveyor well before fieldwork is carried out.

The contents of the guidance are linked to the sequence of questions on the 2021 Survey form and are largely self-explanatory. Special icons are used to highlight issues requiring particular attention, such as when health and safety issues may be of special significance, features that are particularly rare in the UK, and where photos or videos help to illustrate features.

Essential equipment for undertaking cRHS field surveys includes (see photos below): 

  • waterproofs (thigh waders preferred)
  • survey forms in a waterproof document holder; 
  • laminated mini-manual and spot-check key; 
  • a 2m ranging-pole; 
  • an electronic laser range-finder; 
  • a camera (smart phone); 
  • a 360 camera such 
  • a global positioning system for recording geographic coordinates or alternatively a smart phone. 

Thigh WadersWeather writercRHS mini-manualRanging polesLaser range finder360 camera

If the planned means of communication is by mobile phone, it is important to check that there is an adequate signal in the area being surveyed.

Health and safety

It is imperative that all surveys are conducted in conditions which are safe for surveyors. A health and safety assessment is an integral part of the survey and the form must be completed before embarking on the survey, and attached with the completed survey forms. An adequate Lone Working Guidance must be followed and surveyors must never put themselves in a position in which they are not in control. In areas of high risk, it is strongly recommended that a team of two undertakes a survey. Not starting, or abandoning, a survey when the risk is too high should be the principle that applies throughout.

Access and permissions

Whenever practicable, permission from landowners and occupiers should be obtained before surveys are carried out. This is not always feasible or possible, so if challenged cRHS surveyors should be polite, courteous and provide an explanation of what they are doing and why, and on whose authority. In some instances, this may mean having to return to do the survey if the landowner requires further clarification as to the purpose of the work. Identification must be carried by surveyors at all times. Surveyors should comply with disinfection requests from landowners. Surveyors can offer to provide information to landowners if they are interested in receiving it.

Preparatory work

Experience suggests that some cRHS surveyors, no matter how experienced, can still overlook channel modifications. It is therefore recommended that some preparatory briefing is undertaken before visiting the site. For example, looking at the river shape and river name on a map will provide clues as to whether the watercourse has undergone historical channel management. Documentation of past flood defence works is also a source of invaluable information. Such information will help provide context for site characterisation, but should NOT over-ride field observations.

The survey form

The cRHS survey form is three pages long and is accompanied by a separate 8-page mini-manual. The health and safety form is integral to the survey and should be attached to the cRHS form. It is recommended that a clipboard or “Weather-writer” is used as well as a waterproof laminated version of mini-manual taken into the field at all times.

Surveyors are required to record the presence, absence, and in some cases the number or extent, of specific features. Four basic types of records are made:

      • counting the number of certain features within the whole 500m site (e.g. artificial features);
      • ticking boxes () to indicate whether a feature is absent, present or extensive;
      • entering a two-letter acronym for features in the spot-check section;
      • taking measurements of the channel such as height, width and depth.

Where there is a choice of features to be scored, but only a single entry is allowed, boxes on the survey form are either ‘shadowed’ () or have emboldened edges (see left bank material example below).

General site and surveyor information

Information about the surveyor, general site characteristics and details about when and how the survey has been undertaken are entered in Section A and B on Page 1.  For most accurate recording, it is best to survey from both the river and the bank, but the overriding importance of health and safety issues will determine precisely how the survey is undertaken. Most of the information in both Sections A and B of the form can be completed on arrival at a site, or at the end of the survey, as appropriate.  The actual number (including zero) of artificial features such as weirs and bridges is recorded in Section C. This is best done by keeping a cumulative record of the number of these individual features when walking between spot-checks, and then tallying them up on completion of the survey. Please remember to take photographs of any structure recorded.

Suitable conditions and season

cRHS should never be carried out during flood (spate) flows because there are major safety risks involved. High water levels and turbidity will also obscure many of the features cRHS is designed to record and give a false impression of flow-types compared with those expected under dry-weather conditions. If a prolonged period of heavy rain occurs, a survey should be delayed until both water level and clarity, return to acceptable levels.In some lowland UK rivers abundant growth by emergent and bankside vegetation in summer will obscure some channel features.Surveys during this period should be avoided: May and June are considered the most suitable months. Upland rivers with little or no emergent vegetation are suitable for surveying over a much longer season. If, for special reasons, surveys have to be carried out during non-optimal moths, interpretation of the results will need to take full account of seasonal aquatic and bankside vegetation growth. Likewise, in countries with different climatic conditions from the UK, surveys should be ideally carried out when aquatic vegetation growth is evident, but not excessive, and water levels are not high.

Quality control

Each RHS form must be checked for completeness. An extra two minutes for quality control at the end of each survey is invaluable, because incomplete forms will be returned, and a re-survey may be needed. It is important that completed cRHS forms are legible, the pages stapled together with a site reference clearly marked on all pages. If an extra sheet is used for additional observations, make sure this is similarly marked and firmly attached. Of equal importance is the need to clearly label all photographs, and ensure they match the references given on page 1 of the form. A data input software exist for the ctitizen River Habitat Survey that also enable the calculation of various indices such as the Habitat Modification Score (HMS) and Habitat Quality Assessment Score (HQA). Please refer to the RHS website 

Contact for enquiries

Queries and further information on this manual should be addressed to:

The RRC, 2nd Floor Ziggurat, Vincent Building (B52a), Cranfield University, Cranfield, Bedfordshire, MK43 0AL

+44 1234 752979

Created with the Personal Edition of HelpNDoc: Free Kindle producer