Session 1 · TRACE: Causes & Consequences
Stopbanks and warnings
- 10 minWhat is a stopbank? A long bank of earth that keeps a river in its channel. Look at Edgecumbe 2017: what happened when one gave way?
- 20 minStopbank challenge: in your sand river model, build clay stopbanks along the floodplain. Test with a normal flow and then a big flood. Measure where the water goes. What happens downstream?
- 15 minForecasting and warnings: how do MetService, the regional council's river gauges and civil defence alerts work together? Draw the chain from raindrop to text message.
- 5 minRecord: what can stopbanks do, and what can't they do?
Session 2 · TRACE: Causes & Consequences
Fieldwork: our catchment
- 10 minSafety briefing and roles: mapper, measurer, photographer, recorder.
- 30 minSurvey a stretch of stream bank or the school grounds: estimate vegetation cover, count and record debris, and map impermeable surfaces on a grid. Mark any drains that lead to the stream.
- 10 minBack in class: shade your survey map and calculate the percentage of hard surfaces.
Getting started
Use the survey grid with categories printed and a partner to record while you measure.
Stretch
Find your school or town on the regional council's flood-hazard map and give six-figure grid references for the three most at-risk places.
Checkpoint
Each group has stopbank test results and a survey map with a calculated percentage of hard surfaces.
Activities for this week
- Stopbank challenge: What can a stopbank do, and what can't it do?
- Catchment fieldwork survey: How much of our catchment lets rain soak in?
Useful this week
- Floods ↗ Why New Zealand rivers flood, and big floods including Edgecumbe 2017.
- Natural Hazards and Flood Management ↗ How the Manawatū–Whanganui council manages stopbanks, river gauges and warnings.
- LAWA: Land, Air, Water Aotearoa ↗ River flow and water data for rivers near you.