Resource Database: Geography, Earth and Environmental Sciences

Title Weathering, Rainsplash and Rivers
Originator Callum Firth
Department Department of Geography and Earth Sciences, Brunel University, Uxbridge, Middx. UB8 3PH
Tel. +44 (0)1895 203215
Fax +44 (0)1895 203217


Within a module on Global Geomorphology student groups choose one semi-structured experiment out of three (freeze-thaw, rainsplash erosion, channel development). Lectures on processes are run alongside the practicals. Each experiment simulates geomorphic processes using simple materials and equipment. For the simulation of freeze-thaw weathering, students are provided with a domestic freezer, cylinders of sandstone, chalk and granite (prepared in the rock-cutting lab.) and four specified conditions: outside the freezer, dry and exposed to freezing cycles, wet and exposed to freezing cycles, and wet and saline and exposed to freezing cycles. Students choose the frequency of cycle, the number of cycles, and the concentration of salt. It works well, with differences between rock types, and also forms of disintegration. However the emphasis is on the experimental design, and the use of literature, rather than the exact outcome.

The channel development experiment operates within a narrow flume which can be set at various angles and used with different sediment types. The rainsplash experiment is more open for student design. They have to model sediment on a slope at a particular angle and then decide how to deliver rain of a chosen intensity (for example, by pipette, meshes to drip, slow spinning through a fan, hose and sprinkler). The sediment or soil is usually placed on large diameter filter paper, marked 'upslope' and 'downslope' and the amount of sediment moved by rainsplash is recorded by weighing these sectors.

There is a follow-up tutorial with teaching staff, to examine the data, and consider progress.


Techniques included:

Management of laboratory access:

Students are introduced to the materials in an initial 45 minute session following the introductory lecture. They then book in with the support staff and laboratory to conduct the experiments over a five week period.


Written up individually as a scientific report. Students are given guidelines for writing, and the report is expected to include references to literature and statistical analysis if the data are appropriate. This counts as 25% of the module, with 25% on fieldwork and 50% on the exam.


Channel development
Experimental design

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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