Main idea

A river watershed or a river basin represents a basic geographic unit, in which all surface waters and groundwater are connected into one water system. Therefore, any activities that can influence the quality or quantity of water can have an effect on a downstream section of the river (floods, droughts, accumulation of pollution, etc.).

Goal

To relate the river basin concept to students’ local environment. At the same time, to demonstrate that activities in the upper section of a river can have an effect in the downstream section.

Concepts

river basins → river basin district; water balance; upstream, downstream;

Introduction: Upstream, downstream

Start a discussion with clarifying the concepts upstream and downstream. Then refer to the experiments from previous lesson and point out the activities that can influence the river downstream.

  • What do the concepts upstream and downstream mean?
  • What kind of activities can have an influence downstream? (pollution from upstream can accumulate downstream and cause blooms of algae; urbanization upstream or cutting down forests in the upper catchment can speed up runoff and cause floods downstream, etc.)

Activities in this lesson

Mapping the river watershed area
1.2.1
Subject: Art and craft, Biology, Geography
Age group: 10 - 12, 13 and up
Type of activity: Project
Number of participants: Individual, Paired
The size of a watershed area
1.2.2
Subject: Art and craft, Biology, Geography, Math, Physics
Age group: 13 and up
Type of activity: Project
Number of participants: Individual, Paired

Discussion: A Water Balance

Start a discussion with clarifying the concepts water balance, upstream and downstream. Then refer to the experiments and point out the activities that can influence the river downstream.

  • What does the concept a water balance mean? Use the analogy of balancing a household budget with income, savings and expenditures. In hydrology, a water balance is a balance of gains and losses of water described as the flow of water in and out of a water system: precipitation minus evapotranpiration minus changes in storage (due to snow, glaciers, lakes, groundwater) = discharge that fills the rivers.
  • What kind of activities can have an influence on water balance in downstream countries? (urbanization upstream or cutting down forests in the upper catchment can speed up runoff and cause floods downstream, building damns and accumulating water upstream for irrigation can cause droughts downstream etc.)