Talk:River Taff

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Realignment in south Cardiff[edit]

Old maps indicate that the course of the river was realigned between Grangetown and Butetown in south Cardiff, some time after the Second World War.[1] Can we find a clearer source with a date for when this was done? Verbcatcher (talk) 01:20, 2 October 2020 (UTC)

This gives details of a major flood in late December 1979, and notes that £3 million was spent on flood defences afterwards. The river was made wider and deeper, and solid banks were constructed between the Millennium Stadium and Fitzhamon Embankment. I'm not exactly sure where Fitzhamon Embankment is. This NRA document shows the new course with the old course still clearly visible, before it was infilled and developed. Bob1960evens (talk) 18:10, 26 October 2020 (UTC)

@Bob1960evens: Thank you for looking this up. The Wales Online article only describes the flood prevention works upstream of the railway bridge near Cardiff Central Station. (Fitzharmon Embankement is on the bank opposite the Millennium Stadium.) I found this paragraph on page 65 of the NRA report:
  • The Cardiff Flood Alleviation Scheme was constructed between 1980 and 1983 and extends from just downstream of Clarence Bridge, through the City to Llandaff Weir. This includes Pontcanna Fields and Bute Park which form an important flood storage area in times of extreme flooding. The design standard of this scheme is in excess of 1 in 200 years.
I was referring to the straightening and probable dredging of the river upstream of the Clarence Road bridge. This is in the area described in the NRA report, but it is unclear whether the realignment was part of this scheme. The £3M cost mentioned in the Wales Online article seems low if this was included. Avondale Gardens and the southern end of Taff Embankment in Grangetown are on land that would have been reclaimed by this river realignment. The housing there looks like it was built after about 1980, which supports a 1980-83 date for this realigment.
We should add a section on flooding and flood prevention, which should include the 1979 Cardiff floods and the 2020 Pontypridd floods. Verbcatcher (talk) 23:41, 26 October 2020 (UTC)
@Verbcatcher: Yes. I am working my way downstream at the moment, describing the course. I normally do a section on water quality as well, but while the data is freely available for the rivers of England, I have not found a similar source for Wales yet. I have also found a whole lot of stuff about the railway diversion, which caused the board of health some angst for a number of years. Bob1960evens (talk) 12:59, 30 October 2020 (UTC)

Length of river[edit]

Just to alert editors to the fact that the given length of 64km is incorrect (and doesn't appear to be referenced). I have measured the length of the river in detail from source to the county limit at its entry into the Severn estuary using an on-line measuring tool on detailed OS mapping. Comparison with aerial photography suggests that the figure of 67.1km which this produces is itself short of the actual length. This is of course original research on my part and so not acceptable for inclusion in the article but it does flag up the desirability of finding suitably referenced material of better accuracy. incidentally this will be shorter than historic length due to measuring in straight lines through the open water of three reservoirs and Cardiff Bay whereas the previous channel meandered. thanks Geopersona (talk) 08:07, 18 November 2020 (UTC)

Just to note that the issue of its length has come up in talk previously - see archive 1 - though on that occasion, for some obscure reason, an editor was offering up an 'OR' measurement of the river from a random point on the Taf Fechan down to Cardiff. The point was also made that the length depends upon the scale at which it is measured. There is truth in that to a point, but with centre lines of rivers, by venturing to larger scales you can home in on an accurate figure. That's to say it's not a truly an exercise in fractals unlike measuring coastlines. cheers Geopersona (talk) 08:29, 18 November 2020 (UTC)
I have changed the length to 67 km, citing the following source:
  • Pickup, R. W.; Rhodes, G.; Arnott, S.; Sidi-Boumedine, K.; Bull, T. J.; Weightman, A.; Hurley, M.; Hermon-Taylor, J. (April 2005). "Mycobacterium avium subsp. paratuberculosis in the Catchment Area and Water of the River Taff in South Wales, United Kingdom, and Its Potential Relationship to Clustering of Crohn's Disease Cases in the City of Cardiff". Applied and Environmental Microbiology. 71 (4): 2133. doi:10.1128/AEM.71.4.2130-2139.2005. The longest path length of the river Taff uninterrupted by inflows is 67 km
Verbcatcher (talk) 15:53, 12 December 2020 (UTC)
Wonderful - good work! Geopersona (talk) 18:54, 12 December 2020 (UTC)