The drought mystery lesson

Transcription

1 The drought mystery lesson This is a thinking skills lesson, with extension questions, to deepen students understanding of the issues involved in a drought. This lesson could be used after the KS3 or KS4 main lesson, as students will have more background information about drought issues. Before the lesson Have copies of a block diagram (pages 3 - ) showing all the processes that are typed in capital letters in the texts on pages 6, 7 and 8. Choose the version best suited to your students needs. (See Starter.) Have a set of Drought mystery cards ready for each group or pair of students (see pages 6-8). Different colours are recommended so students working adjacent to each other do not mix their cards up. Have uncut, paper copies of the card sheets for each student. Have A3 sheets of paper for each group or pair of students. They may need to stick two sheets together for the final product, which would have the cut paper copies of the cards stuck down. Students will need a clear table space to lay the cards out and move them around. The mystery question is: Why would we still be in a drought, and possibly have a hosepipe ban, even if it rained a lot in the summer? Starter The block diagram on page 3 can be used as a starter to remind students of the physical processes of the water cycle and how they contribute to water supplies. Three versions of the water cycle diagram have been provided: (i) Completed labels for students who have not studied the water cycle in great detail (page 3). Water cycle diagram Evapotranspiration Transpiration Transpiration Evaporation (ii) Label lines (with starting letters only) for those who need the support of the cards to work out the labels (page 4). (iii) Blank label lines only, for those who have studied the water cycle in detail and can be given the diagram to label from memory, as a revision exercise (page ). Infiltration Root Zone Percolation Recharge Groundwater Flow Permeable Rocks Overland Flow Pumping Station Borehole Soil Infiltration Unsaturated Zone Water Table Saturated Zone

2 The drought mystery lesson Group work. Students need to read through the Drought mystery cards and, where appropriate, label the processes (in capital letters) on their diagram of the water cycle. Choose the diagram that best suits the needs of each group (see pages 3 - ). 2. Through discussion, students could be encouraged to classify the cards into groups according to common themes: Weather & water cycle Groundwater Water supply Water management Card reference A, D, E, F, O, U C, G, I, L B, H, K, M, Q, S J, N, P, R, T More able or older students could be encouraged to read the cards and try to decide on categories themselves. 3. After classification, students should be encouraged to sequence the cards within each group to make connections and answer the mystery question. 4. The cards are labelled with letters so that the arrangements of cards the students devise can be represented in a small flow diagram. Feedback to the teacher and discussion of the best arrangement should happen at this stage.. Then students can stick the cards down onto A3 paper in a logical flow diagram with connecting arrows, writing the explanation of the links along the connecting arrows. (See example flow diagram below.) 6. Students could then illustrate the backdrop to the flow diagram with diagrams to show the processes involved or with some pictures downloaded from the Anglian Water website. Extension questions. Why is persistent gentle rainfall better for recharging groundwater than a downpour? 2. Why is winter rainfall so important? 3. Why is groundwater likely to have been stored underground for hundreds of years? Example flow diagram U water lost to atmosphere D RAINFALL E A F O groundwater supplies river flow reduced groundwater supplies I C L G water supply is taken from groundwater M S K Q B causes more problems even more water will be needed T prevents water loss R N planning planning for the future more droughts due to climate change? P cause H demands on groundwater other than domestic population increase J 2

3 The drought mystery lesson Water cycle diagram (i) Evapotranspiration Transpiration Transpiration Evaporation Infiltration Root Zone Percolation Recharge Groundwater Flow Permeable Rocks Overland Flow Infiltration Borehole Pumping Station Water Table Saturated Zone Soil Unsaturated Zone 3

4 The drought mystery lesson Water cycle diagram (ii) Evapotranspiration Evaporation 4 2 Root Zone 3 8 Overland Flow 6 7 Borehole Soil Unsaturated Zone Saturated Zone Can you write the missing eight labels? I 2 P 3 R 4 G F T 6 P S 7 W T 8 P R 4

5 The drought mystery lesson Water cycle diagram (iii) Evapotranspiration Evaporation 4 2 Root Zone 3 8 Overland Flow 6 7 Borehole Soil Unsaturated Zone Saturated Zone Can you write the missing eight labels?

6 Drought mystery cards A The water in the west of the Anglian Water region comes mainly from reservoirs, which are used to store water taken from rivers. The level of water in Rutland Water reservoir (in the west of the region) became exceptionally low in March 202. B The Anglian Water region s population is predicted to grow by some 80,000 by 203. Growth areas such as Milton Keynes have high targets for house building over the next 2 years. C Typical speeds of GROUNDWATER FLOW are between metre/year and metre/day, which is very slow. D Large amounts of water from the soil and the permeable rock below it flow through plants and back into the atmosphere in the process of TRANSPIRATION. E The rainfall or snowmelt INFILTRATES into the soil. It then PERCOLATES down through the permeable rock until it reaches the water table. F Long periods of persistent gentle rainfall especially in winter are needed to RECHARGE groundwater supplies. Summer downpours help very little, if at all. G The east of the Anglian Water region relies mainly on groundwater from aquifers, which underlie large parts of East Anglia. H The Anglian Water region has 8% of the UK s best agricultural soils. Agriculture uses % of the region s water but on some days this can rise to over 60% of water being used for irrigation. This happens in the driest periods when demand from all users is high. Over 000 agri-businesses rely on irrigation to produce 30% of the UK s potatoes and 2% of all vegetables and fruit. 6

7 Drought mystery cards I Groundwater is found in the spaces (pores) in rocks which hold water (PERMEABLE ROCKS) e.g. chalk. The top of the groundwater zone is called the WATER TABLE. It may be at or very close to the surface, or hundreds of metres down. J As demand will continue to rise, and climate change could make supply more difficult, Anglian Water will build a new reservoir in southern Lincolnshire to store winter flows and may consider transferring water from other parts of the country as well. K Lack of rain or pumping too much water out of the ground at PUMPING STATIONS may lower the level of the water table. L Groundwater is likely to have been stored underground for hundreds of years. M When a well or borehole is dug in permeable rocks to a depth below the water table, water will begin to flow into the hole. N Anglian Water s Water Resource Management Plan aims to control demand for water through metering, promoting the efficient use of water and controlling leakage from pipes. O The Anglian Water region had two dry winters in a row (200/ and 20/2). 20 was the driest year since 92 as the region had only two-thirds of its average annual rainfall (426 mm instead of the 600 mm average). P Pollution of groundwater in the Anglian Water region mainly comes from agriculture in the form of run-off of fertilisers and manure from farms. 7

8 Drought mystery cards Q The Anglian Water region was classified as in serious water stress by the Environment Agency in 202. R The Anglian Water region has one of the lowest leakage rates in the UK and has a big team of technicians to deal with leaks and burst pipes to minimise wastage. S The water for our taps is taken from rivers and groundwater. During a drought there is less water available and we have to balance our needs with those of the environment. T The key to managing groundwater supplies is that You can t take out more than is put in. It works like any other storage system, but unlike a bank, you can t go overdrawn. U According to the Met Office (in March 202), rainfall will continue to be below the national average in East Anglia. 8