dcf.cymru stimulus sheet · Digital Media and Film · Year 10
The town, the people, the accounts, the news organisations and every figure on this sheet are invented. The way the story spreads is real: it is how misinformation travels during real emergencies.
Cwmderwen is a small town in a South Wales valley. The Afon Derwen runs through the middle of it. Above the town is Llyn Derwen, a reservoir held back by a stone dam. On a Saturday in November it rained heavily all day. By early evening the river was over its banks. Six pieces of content about that evening are printed below, in the order they were published. All times are in the evening, using the 24-hour clock.
Account: @cwmderwen_walks. Name on profile: Siân Pritchard, leader of Cwmderwen Walking Group. On the app since 2019, 3,400 followers. Her earlier videos are walks around the valley.
Video (38 seconds): filmed from the road bridge on Heol yr Afon. The river is brown and fast and has covered the riverside path. The rugby club floodlights are in the background. A council worker in a high-visibility jacket ties a sign to the footbridge railings. The sign says, in Welsh and English: “Mae’r bont droed ar gau. Cadwch draw o lwybr yr afon heno.” “The footbridge is closed. Keep away from the river path tonight.”
Caption: “Taken 5 mins ago from the road bridge. River’s over the path by the rugby club and the council have shut the footbridge. Stay off the riverside path tonight please.”
Account: @WalesNewsNOW24. Name on profile: Wales News NOW. No person named. Joined 3 weeks ago, 212 followers. Profile picture: the word BREAKING in white on red.
Post: “BREAKING!! Llyn Derwen dam wall has CRACKED. Whole of Cwmderwen being EVACUATED tonight. The media won’t tell you this. SHARE before they delete it!!!”
Photo: a huge concrete dam with water pouring over the top, in a steep valley with pine forest and snowy mountains behind it. There is no caption and no date.
Group: Cwmderwen Community Noticeboard, 4,900 members. A member has shared Item B with this message:
“Is this true?? My cousin works for the council and says they’re getting the leisure centre ready for people. Really scared, my nan lives up by the reservoir.”
Comments underneath (first four of 212):
Valley Voice Online, a local news website with a newsroom in the valley. By Rhodri Evans, community reporter.
Headline: Footbridge closed and 11 homes cleared as river rises in Cwmderwen
Natural Resources Wales has issued a flood warning for the Afon Derwen at Cwmderwen. The council closed the footbridge by the rugby club at about 17:30. At 18:15, council staff asked the families in 11 houses on Glan yr Afon to leave their homes as a precaution. A rest centre has opened at Cwmderwen Leisure Centre.
A council spokesperson said: “This is a precaution for the houses closest to the river. Nobody else needs to leave their home. Please keep away from the riverbank.”
UPDATE 19:15: Posts on social media claiming that the Llyn Derwen dam has cracked are false, the reservoir’s owner says. An engineer inspected the dam at 19:00 and found no damage. The water is 1.2 metres below the overflow. A police spokesperson asked people “not to share posts you cannot check, because they frighten people and block phone lines”.
Wales Tonight, a regional evening news programme. Transcript of the Cwmderwen report (1 minute 50 seconds).
PRESENTER (in the studio): Families in one Rhondda Cynon Taf town have spent the evening in a rest centre after the river burst its banks. Our reporter is there.
REPORTER (live, beside the road bridge, in the rain): The river here is the highest people can remember. Behind me, 11 homes on Glan yr Afon have been cleared. I have spoken to the reservoir’s owner, and I can tell you the dam above the town is safe. The picture you may have seen online, of water pouring over a dam, was not taken in Wales.
RESIDENT (interview): I saw that post and I panicked. I rang my mother five times. Then I saw the council’s page and calmed down.
Check First Cymru, a fact-checking website. Each article lists its sources at the bottom.
Headline: No, the Llyn Derwen dam has not cracked
Verdict: FALSE. A reverse image search shows the photo in the viral post was first published in 2021, in a news report about a dam in another country. Llyn Derwen dam is built of stone, not concrete. The reservoir’s owner confirmed an inspection at 19:00 found no damage. The account @WalesNewsNOW24 has changed its name twice in three weeks and has posted two other false emergency claims.
Sources listed: statement from the reservoir’s owner, 19:05; Natural Resources Wales flood warning page; Valley Voice Online article, updated 19:15; reverse image search results.
Views and shares of each item, counted at three times on the same evening. A dash means the item had not been published yet.
| Item | Views at 19:00 | Views at 20:00 | Views at 22:00 | Shares by 22:00 |
|---|---|---|---|---|
| A: citizen video | 6,200 | 12,800 | 18,400 | 1,150 |
| B: “dam CRACKED” post | 94,000 | 251,000 | 486,000 | 21,300 |
| C: community group share | 3,900 | 4,600 | 4,800 | not counted |
| D: news website article | 3,100 | 22,500 | 41,000 | 1,900 |
| E: TV bulletin clip online | - | 8,700 | 27,600 | 640 |
| F: fact-check | - | - | 19,300 | 2,050 |
Group posts count views differently, so the shares on Item C were not counted.
By 23:00 the river had started to fall. Nobody was hurt. The families from Glan yr Afon went home the next afternoon. The emergency phone lines took 140 calls about the dam that evening.