Resource Database: Geography, Earth and Environmental Sciences

Title Experiments in Soil Erosion
Originator Martin Haigh
Department Oxford Brookes University, Gipsy Lane Campus, Headington, Oxford, OX3 0BP
Tel. +44 (0)1865 483785
Fax +44 (0)1865 483937
Email mjhaig@brookes.ac.uk

Context:

As part of a module entitled Soil Conservation students work in self-created teams to explore the controls of soil erosion (Haigh & Kilmartin, 1987). They use a large laboratory soil tray as a test bed for conducting their own investigations into the ways in which slope angle, surface water run off, subsurface water, sediment size, organic matter, surface cover, surface roughness, rilling and/or simulated rainfall affect sediment mobilisation. They may also design experiments that test the effectiveness of different erosion control technologies, such as transverse barriers, mulches or terraces. Lectures in soil erosion processes and technologies run alongside the practical project. The project is supported by a 40 page workbook.

Student teams are encouraged to create their own experimental plans and assign roles to team members. It is recommended that one role should be 'library research'. Student plans are vetted by the entire class for relevance to the course. If deemed worthwhile, student teams are allowed to bid for three or four 4-hour laboratory sessions. This allows them time to set up and run their experiment(s). Since the experiment is part of the teaching programme of the course, students are required to bring their findings back to the class as a formal presentation. Since many experiments take several hours to set up and, usually, a few minutes to run, students are encouraged to use video to record their experiences.

Aims:

Learning objectives:

Students will:
  1. gain understanding of the character of erosion processes and the problems of erosion control technologies by direct experience (one of the most important understandings gained is that erosion rates are governed by exponential laws)
  2. learn how to design and execute their own 'control' experiment or suite of experiments
  3. reinforce prior learning of team-working skills
  4. gain further experience of managing the logistics of problem-solving within strict time and resource constraints

Techniques included:

Management of laboratory access:

The flume is housed in its own small (listed) building, and access is very restricted. A small group of students and the technician is all that can fit in. The flume is demonstrated for the students for one session, and then they book in times more flexibly to run their own experiments. As a consequence of health and safety issues, the flume is only run with a technician present.

Assessment:

The student group produces an initial plan, in the form of an oral presentation, to the whole class, after seeing the flume demonstrated. This is 5% of the module assessment. The main write-up is a group report in the format of a scientific paper, with references. This is 20% of the assessment. The group also give an oral presentation, with videos if available, to the whole class, accompanied by a poster. This is 15%. The module also includes weekly class tests on the lecture content. Although these are only awarded 2% each they are popular with the students and maintain attendance and revision of the conceptual part of the course.

Keywords:

Experimental design
Group work
Laboratory work
Skills development
Soil erosion

This is one of the case studies which appears in the GDN Guide "Practicals and Laboratory Work in Geography"


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Page created 28 November 1998
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