River Habitat Survey is a method developed in the UK to characterise and assess, in broad simple terms, the physical character of freshwater streams and small rivers. It is carried out along a 500m length of river. Observations on channel features and modifications are made at 10 equally spaced spot-checks, together with an overall “sweep-up” summary for the whole site. Other information such as valley form and land-use in the river corridor is also collected.
Field survey follows the strict protocols given in the 2003 RHS manual and surveyors in the UK are required to be fully trained and accredited. Beyond the UK, RHS has also been carried out in several other European countries. For instance, more than 200 RHS surveys were included during the STAR project; in addition, 200 sites have been surveyed in Italy; more than 600 in Poland, over 700 in Portugal and almost 800 in the Cantabrian Region of northern Spain. The RHS manual has been adapted and translated into Italian, French, German and Polish, whilst Portuguese and Spanish versions have also been developed. RHS survey data and site photographs are entered onto a computer database.
The UK database now contains field observations, map-derived information and photographs from more than 24,000 surveys undertaken since 1994. During 1994-96, a stratified random network of nearly 5000 sites provided baseline information about the physical character from a geographically representative sample of streams and rivers across the UK. A second survey in England and Wales was carried out during 2007 and 2008 and summary information, including changes since the original baseline, was published in October 2010 (see ‘Resource’ section).
River Habitat Survey data have been analysed and used as part of research projects both in the UK and abroad (see ‘Applications’ section). An educational CD-ROM, The Riverside Explorer, was developed in the UK and distributed to every school in England and Wales. Recently, a Decision Support System for assessing habitat quality and prioritising sites for habitat enhancement work called ToolHab was developed and is in the process of being tested in the Environment Agency, England and Wales. Research projects have been carried out on urban rivers and RHS data have been used for describing habitats for various species from macro invertebrate to fish, birds and macrophytes.
The following sections will provide some historical background and more details on the survey methodology. A lot of information can be found in the ‘Resource’ section. More will be added in weeks to come.