Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Free course



Course image: Nic Redhead [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] in Flickr made available under Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence.

The content acknowledged below is Proprietary (see terms and conditions). This content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 Licence

Grateful acknowledgement is made to the following sources for permission to reproduce material in this unit:

Figures 1.1, 1.2, 1.3, 1.10, 2.4, 2.8, 2.10, 2.11, 2.11, 2.17, 3.2, 3.3, 4.2, 4.3 & 4.7 Courtesy of the Environment Agency;

Figures 1.4, 1.8a, b, 2.3, 2.12, 2.14, 2.15, 2.16, 3.1, 4.8 Copyright © Mike Dodd/The Open University;

Figure 1.7 Andy Harmer/Science Photo Library;

Figure 1.8c Courtesy of Dr John Madsen/Minnesota State University;

Figure 1.12 Copyright Dr Julian Thompson, Wetland Research Unit, Department of Geography, University College, London;

Figure 2.1 Copyright © Sukurta Viliaus & Co.;

Figures 2.2, 2.5a & 3.4 Copyright © Owen Mountford/Centre for Ecology and Hydrology;

Figure 2.5b Copyright © Peter Gathercole/Oxford Scientific Films;

Figure 2.6 Copyright © Alistair MacEwen/Oxford Scientific Films;

Figure 2.7 Copyright © BBC Worldwide;

Figure 2.18 With permission from Professor Chris Kjeldsen, Biology Department, Sonoma State University;

Figure 2.24 Graham Day;

Figure 4.4 Copyright © Peter Leeds-Harrison/Cranfield University;

Figure 4.5 Copyright © ARM Limited. Reproduced with permission of ARM Limited, Rydal House, Colton Road, Rugeley, Staffordshire, WS15 3HF, UK,, designers of reed beds and welands for wastewater treatment;

Figure 4.6 Pisces Conservation Limited.

Courtesy of the Environment Agency;

Don't miss out:

If reading this text has inspired you to learn more, you may be interested in joining the millions of people who discover our free learning resources and qualifications by visiting The Open University - openlearn/ free-courses


Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to University-level study, we offer two introductory routes to our qualifications. You could either choose to start with an Access module, or a module which allows you to count your previous learning towards an Open University qualification. Read our guide on Where to take your learning next for more information.

Not ready for formal University study? Then browse over 1000 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371