Used with AS students.

3. The Water Cycle The water cycle is a closed system because "water" comes in three forms or phases: solid, liquid and gas. Water can change phases by melting, evaporating, sublimating, freezing or condensing, but it is still water. The "closed system" is one where the basic material is neither being created nor destroyed-- just moving between phases.

4. The water cycle

5. So why is the hydrological cycle not closed? In an open system there is movement of both energy and materials in and out of the system. All environmental systems, including the hydrological cycle, are open systems.

6. The Drainage basin

7. Where can drip go?

8. clouds Vegetation store Trees and plants Surface store Rivers, lakes and glaciers Soil store Groundwater store Sea Key The arrows show transfers of water The boxes show stores of water Words to add to arrows not labelled. Evaporation (twice), Interception, Infiltration, Evapotranspiration, Percolation, Infiltration. Surface runoff, Groundwater flow, Throughflow, condensation. The arrow with a star does not need a label.

9. Outcomes 1. All students will know key terminology for hydrological cycle and drainage basin. Why rivers are important to man and the basics of hydrological cycle. 2. Some students will also be able to describe the cycle as a system of inputs stores and outputs. 3. A few will progress even further to know difference between water cycle and hydrological cycle.