Can you help us reach 500? Tell your family, friends, neighbours that Council's 1-in-100 year flood map for Pinehaven (attached) is grossly exaggerated and for the safety of our community it must be corrected and Pinehaven must be provided with proper flood protection.
Council's flood map is inflated by about 100,000 tons of additional floodwater that will hit us if Council's flood model isn't fixed. This is additional stormwater runoff from a future development which the developer is supposed to manage on site, but instead will just be dumped on us because of Council's inflated baseline flood model!
Just how grossly inflated is Council's Pinehaven flood model? Their 100-year flood extents (flood map attached) go way beyond the flood extents of a 500-3,000 year flood event that happened in Pinehaven four days before Christmas in 1976. An engineer's report at the time records that 200mm of rain fell in 6 hours over Pinehaven. The 1976 storm is considered by a hydrological expert to have been a 500 to 3,000 year flood event in Pinehaven:
"I looked at the 1976 event and some of the [flood] report. I actually thought the report was very well done on that event. ... I thought the engineer was pretty brave to say it was 1,000 year rainfall ... back in 1976 … The thing is now with HIRDSv4… that rainfall touches on a 10,000 year event [at Taita, ex-DSIR Research Station].
One thing I ... disagree with is that he [the engineer] put it at a 100 year [flood] return period. I think it was much greater than that. I used two regional flood studies, the McKerchar/Pearson, and the Henderson one, and they run between a 500 year event and a 3,000 year event for what happened in Pinehaven." (Hydrological expert Graeme Horrell, at a Planning Hearing in Upper Hutt, August 2020)
We have over 20 eye-witness accounts of people who observed first-hand the flood extents in Pinehaven in this enormous flood in December 1976. All their written accounts agree that the flood extents in Council's 1-in-100 year flood map (attached) go way beyond the 500 - 3,000 flood extents that occurred in Pinehaven in the 1976 flood.
How did Council and their consultants inflate their 100-year flood extents to go way beyond a massive 500 - 3,000 year flood? In upcoming posts, we'll show you the tricks they used to grossly exaggerate the flood extents in their 100-year flood map (attached).
Meanwhile, thanks again for your support of our petition to Council for proper flood protection for Pinehaven. Help us reach our next goal of 500 supporters! Kia kaha.