To do this, they follow each stream back to its origin and include all of these inside the boundary line of the catchment area. Students identify any land uses or features that they know about. Each group completes a table that lists the human impacts and the possible effects of these impacts on the waterways. The information from the groups is shared in a whole-class discussion. An overhead transparency of the catchment map could be used to locate various features during the discussion.
Students then collate a list of the environmental problems in the catchment area.